/* Matematika — dizajn sistem v1.0
   Čisti CSS, bez frameworka. Moderno, čitljivo, prilagođeno djeci 10-15 god. */
:root {
  --bg: #f8fafc;
  --surface: #ffffff;
  --ink: #0f172a;
  --muted: #64748b;
  --line: #e2e8f0;
  --primary: #4f46e5;
  --primary-600: #4338ca;
  --primary-50: #eef2ff;
  --accent: #f59e0b;
  --accent-50: #fffbeb;
  --success: #059669;
  --success-50: #ecfdf5;
  --danger: #dc2626;
  --danger-50: #fef2f2;
  --info: #0284c7;
  --info-50: #f0f9ff;
  --radius: 16px;
  --radius-sm: 10px;
  --shadow: 0 10px 30px rgba(15, 23, 42, 0.08);
  --shadow-sm: 0 4px 14px rgba(15, 23, 42, 0.07);
  --font: "Nunito", "Inter", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --max: 1120px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font);
  background: var(--bg);
  color: var(--ink);
  line-height: 1.65;
  font-size: 17px;
}
img, svg { max-width: 100%; }
a { color: var(--primary); text-decoration: none; }
a:hover { text-decoration: underline; }

.container { max-width: var(--max); margin: 0 auto; padding: 0 20px; }

/* ---------- Header ---------- */
.site-header {
  position: sticky; top: 0; z-index: 50;
  background: rgba(255,255,255,0.92);
  -webkit-backdrop-filter: blur(10px);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
}
.header-inner {
  display: flex; align-items: center; gap: 16px;
  height: 68px;
}
.logo {
  display: flex; align-items: center; gap: 10px;
  font-weight: 900; font-size: 1.35rem; color: var(--ink);
  text-decoration: none;
}
.logo:hover { text-decoration: none; }
.logo-mark {
  width: 38px; height: 38px; border-radius: 12px;
  background: linear-gradient(135deg, var(--primary), #8b5cf6);
  color: #fff; display: grid; place-items: center;
  font-weight: 900; font-size: 1.3rem;
  box-shadow: var(--shadow-sm);
}
.logo small { font-weight: 700; color: var(--muted); font-size: 0.8rem; display: block; line-height: 1; }
.nav { margin-left: auto; display: flex; align-items: center; gap: 6px; }
.nav a {
  padding: 9px 14px; border-radius: 999px; color: var(--ink);
  font-weight: 800; font-size: 0.95rem;
}
.nav a:hover { background: var(--primary-50); text-decoration: none; }
.nav a.active { background: var(--ink); color: #fff; }
.btn {
  display: inline-flex; align-items: center; gap: 8px;
  border: 0; cursor: pointer; font-family: inherit;
  font-weight: 900; padding: 12px 20px; border-radius: 999px;
  background: var(--primary); color: #fff;
  box-shadow: var(--shadow-sm);
  transition: transform 0.12s ease, box-shadow 0.12s ease;
  font-size: 1rem;
}
.btn:hover { background: var(--primary-600); text-decoration: none; transform: translateY(-1px); }
.btn.secondary { background: #fff; color: var(--ink); border: 2px solid var(--line); box-shadow: none; }
.btn.secondary:hover { border-color: var(--primary); }
.btn.small { padding: 8px 14px; font-size: 0.9rem; }
.hamburger { display: none; margin-left: auto; background: #fff; border: 2px solid var(--line); border-radius: 10px; padding: 8px 12px; font-size: 1.2rem; cursor: pointer; }

/* ---------- Pretraga ---------- */
.search-box { position: relative; display: flex; align-items: center; gap: 6px; margin-left: 12px; }
.search-toggle { display: none; background: #fff; border: 2px solid var(--line); border-radius: 10px; padding: 8px 10px; font-size: 1.05rem; cursor: pointer; }
.search-input {
  width: 190px; padding: 9px 14px; border: 2px solid var(--line); border-radius: 999px;
  font: inherit; font-size: 0.92rem; background: #fff; color: var(--ink);
}
.search-input:focus { outline: none; border-color: var(--primary); box-shadow: 0 0 0 3px var(--primary-50); width: 230px; }
.search-input:focus-visible { outline: 3px solid var(--primary); outline-offset: 2px; }
.search-results {
  position: absolute; top: calc(100% + 8px); right: 0; width: 340px; max-width: 86vw;
  max-height: 70vh; overflow-y: auto; background: #fff; border: 1px solid var(--line);
  border-radius: var(--radius-sm); box-shadow: var(--shadow); padding: 6px; z-index: 60;
}
.search-results[hidden] { display: none; }
.search-result { display: block; padding: 8px 10px; border-radius: 8px; text-decoration: none; color: var(--ink); }
.search-result:hover, .search-result:focus { background: var(--primary-50); text-decoration: none; }
.search-result-title { display: block; font-weight: 800; font-size: 0.95rem; }
.search-result-meta { display: block; font-size: 0.78rem; color: var(--muted); margin-top: 2px; }
.search-empty { padding: 10px; font-size: 0.88rem; color: var(--muted); }

/* ---------- Hero ---------- */
.hero {
  background:
    radial-gradient(600px 300px at 15% 10%, #c7d2fe 0%, transparent 60%),
    radial-gradient(700px 340px at 90% 20%, #fde68a 0%, transparent 55%),
    linear-gradient(180deg, #fff, var(--bg));
  border-bottom: 1px solid var(--line);
  padding: 56px 0 40px;
}
.hero-grid { display: grid; grid-template-columns: 1.15fr 0.85fr; gap: 32px; align-items: center; }
.eyebrow {
  display: inline-flex; align-items: center; gap: 8px;
  background: #fff; border: 1px solid var(--line);
  padding: 6px 12px; border-radius: 999px;
  font-size: 0.85rem; font-weight: 800; color: var(--muted);
}
.hero h1 { font-size: clamp(2rem, 4.5vw, 3.1rem); line-height: 1.08; margin: 14px 0 12px; letter-spacing: -0.02em; }
.hero h1 span { background: linear-gradient(90deg, var(--primary), #8b5cf6); -webkit-background-clip: text; background-clip: text; color: transparent; }
.hero p.lead { font-size: 1.12rem; color: #334155; max-width: 56ch; }
.hero-actions { display: flex; gap: 12px; flex-wrap: wrap; margin-top: 20px; }
.hero-stats { display: flex; gap: 18px; margin-top: 22px; flex-wrap: wrap; }
.stat { background: #fff; border: 1px solid var(--line); border-radius: var(--radius-sm); padding: 10px 14px; box-shadow: var(--shadow-sm); }
.stat b { display: block; font-size: 1.25rem; }
.stat span { font-size: 0.85rem; color: var(--muted); font-weight: 700; }
.hero-card {
  background: var(--ink); color: #fff; border-radius: 20px;
  padding: 24px; box-shadow: var(--shadow);
  position: relative; overflow: hidden;
}
.hero-card::after {
  content: "π √ ∑ ∞ ÷ × − +";
  position: absolute; right: 12px; bottom: 6px; opacity: 0.12;
  font-weight: 900; letter-spacing: 4px;
}
.hero-card h3 { margin: 0 0 8px; }
.mini-list { margin: 12px 0 0; padding: 0; list-style: none; display: grid; gap: 8px; }
.mini-list li { background: rgba(255,255,255,0.08); border: 1px solid rgba(255,255,255,0.14); padding: 10px 12px; border-radius: 12px; font-size: 0.95rem; }

/* ---------- Sections / cards ---------- */
.section { padding: 40px 0; }
.section h2 { font-size: 1.7rem; margin: 0 0 6px; letter-spacing: -0.01em; }
.section .sub { color: var(--muted); margin: 0 0 20px; max-width: 72ch; }
.grid { display: grid; gap: 16px; }
.grid.cols-3 { grid-template-columns: repeat(3, 1fr); }
.grid.cols-2 { grid-template-columns: repeat(2, 1fr); }
.card {
  background: var(--surface); border: 1px solid var(--line);
  border-radius: var(--radius); padding: 20px;
  box-shadow: var(--shadow-sm);
  display: flex; flex-direction: column; gap: 10px;
  transition: transform 0.12s ease;
}
.card:hover { transform: translateY(-2px); }
.card .tag { align-self: flex-start; font-size: 0.78rem; font-weight: 900; letter-spacing: 0.04em; text-transform: uppercase; background: var(--primary-50); color: var(--primary-600); padding: 4px 10px; border-radius: 999px; }
.card .tag.green { background: var(--success-50); color: var(--success); }
.card .tag.amber { background: var(--accent-50); color: #b45309; }
.card .tag.blue { background: var(--info-50); color: var(--info); }
.card h3 { margin: 0; font-size: 1.15rem; }
.card p { margin: 0; color: #475569; font-size: 0.98rem; }
.card .go { margin-top: auto; font-weight: 900; }
.grade-number {
  width: 46px; height: 46px; border-radius: 14px; display: grid; place-items: center;
  font-weight: 900; font-size: 1.3rem; color: #fff;
  background: linear-gradient(135deg, var(--primary), #8b5cf6);
}
.grade-5 { background: linear-gradient(135deg, #4f46e5, #8b5cf6); }
.grade-6 { background: linear-gradient(135deg, #059669, #10b981); }
.grade-7 { background: linear-gradient(135deg, #0284c7, #38bdf8); }
.grade-8 { background: linear-gradient(135deg, #ea580c, #f59e0b); }
.grade-9 { background: linear-gradient(135deg, #dc2626, #f472b6); }
.disabled { opacity: 0.75; }

/* ---------- Breadcrumb + lesson ---------- */
.breadcrumb { font-size: 0.9rem; color: var(--muted); margin: 22px 0 10px; font-weight: 700; }
.breadcrumb a { color: var(--muted); }
.lesson-layout { display: grid; grid-template-columns: 280px 1fr; gap: 24px; align-items: start; }
.toc {
  position: sticky; top: 90px;
  background: #fff; border: 1px solid var(--line); border-radius: var(--radius);
  padding: 16px; box-shadow: var(--shadow-sm);
}
.toc h4 { margin: 0 0 10px; font-size: 0.95rem; text-transform: uppercase; letter-spacing: 0.05em; color: var(--muted); }
.toc ol { margin: 0; padding-left: 20px; display: grid; gap: 6px; font-size: 0.95rem; font-weight: 700; }
.toc a { color: var(--ink); }
.toc a:hover { color: var(--primary); }
.lesson {
  background: #fff; border: 1px solid var(--line); border-radius: 20px;
  padding: clamp(20px, 3vw, 36px); box-shadow: var(--shadow-sm);
}
.lesson h1 { margin-top: 0; font-size: clamp(1.6rem, 3vw, 2.3rem); line-height: 1.15; }
.lesson h2 { margin-top: 34px; padding-top: 18px; border-top: 2px dashed var(--line); }
.lesson h3 { margin-bottom: 6px; }
.callout {
  border-radius: var(--radius-sm); padding: 14px 16px; margin: 16px 0;
  border: 1px solid var(--line); background: var(--bg);
}
.callout.goal { background: var(--primary-50); border-color: #c7d2fe; }
.callout.tip { background: var(--accent-50); border-color: #fde68a; }
.callout.warn { background: var(--danger-50); border-color: #fecaca; }
.callout.good { background: var(--success-50); border-color: #a7f3d0; }
.callout b.title { display: block; margin-bottom: 4px; }
.formula {
  font-size: 1.35rem; font-weight: 900; text-align: center;
  background: var(--ink); color: #fff; border-radius: 14px; padding: 16px;
  margin: 14px 0; letter-spacing: 0.02em;
}
.formula .frac { display: inline-flex; flex-direction: column; vertical-align: middle; margin: 0 6px; font-size: 1.05rem; }
.formula .frac span:first-child { border-bottom: 2px solid #fff; padding: 0 10px; }
.frac-inline { display: inline-flex; flex-direction: column; vertical-align: middle; text-align: center; font-weight: 900; font-size: 0.95em; line-height: 1.25; margin: 0 2px; }
.frac-inline > span:first-child { border-bottom: 2px solid currentColor; padding: 0 8px; }

/* interaktivni vizual */
.viz {
  border: 2px solid var(--line); border-radius: var(--radius);
  background: linear-gradient(180deg, #fff, #f8fafc);
  padding: 18px; margin: 16px 0;
}
.viz h4 { margin: 0 0 4px; }
.viz p.hint { margin: 0 0 12px; color: var(--muted); font-size: 0.95rem; }
.controls { display: flex; gap: 14px; flex-wrap: wrap; align-items: end; margin: 12px 0; }
.control { display: grid; gap: 6px; font-weight: 800; font-size: 0.92rem; }
.control input[type="range"] { width: 200px; accent-color: var(--primary); }
.control input[type="number"] {
  font: inherit; font-weight: 800; padding: 8px 10px; border-radius: 10px;
  border: 2px solid var(--line); width: 130px;
}
.control output { background: var(--ink); color: #fff; padding: 2px 10px; border-radius: 999px; font-size: 0.9rem; }
.viz-canvas { display: grid; place-items: center; padding: 10px 0 4px; }
.pv-table { width: 100%; border-collapse: separate; border-spacing: 0; margin: 12px 0; overflow: hidden; border-radius: 12px; border: 2px solid var(--line); }
.pv-table th, .pv-table td { padding: 10px 8px; text-align: center; border-bottom: 1px solid var(--line); font-weight: 800; }
.pv-table th { background: var(--ink); color: #fff; font-size: 0.85rem; }
.pv-table th small { display: block; font-weight: 700; opacity: 0.7; }
.pv-table td.big { font-size: 1.5rem; background: var(--primary-50); }
.pv-table tr:last-child td { border-bottom: 0; }

/* koraci */
.steps { display: grid; gap: 10px; margin: 14px 0; }
.step {
  border: 1px solid var(--line); border-radius: 12px; padding: 12px 14px;
  background: #fff; display: none;
}
.step.visible { display: block; animation: pop 0.25s ease; }
.step .k { display: inline-grid; place-items: center; width: 28px; height: 28px; border-radius: 999px; background: var(--primary); color: #fff; font-weight: 900; margin-right: 8px; }
@keyframes pop { from { opacity: 0; transform: translateY(6px); } to { opacity: 1; transform: none; } }
.step-nav { display: flex; gap: 10px; margin-top: 6px; flex-wrap: wrap; }

/* primjeri i zadaci */
.example { border-left: 5px solid var(--primary); background: var(--primary-50); border-radius: 0 12px 12px 0; padding: 12px 14px; margin: 12px 0; }
.quiz { border: 2px dashed #c7d2fe; border-radius: var(--radius); padding: 16px; margin: 14px 0; background: #fff; }
.quiz .q { font-weight: 900; margin: 0 0 8px; }
.quiz .opts { display: grid; gap: 8px; margin: 10px 0; }
.quiz button.opt {
  text-align: left; font: inherit; font-weight: 800; cursor: pointer;
  background: var(--bg); border: 2px solid var(--line); border-radius: 12px; padding: 10px 12px;
}
.quiz button.opt:hover { border-color: var(--primary); }
.quiz button.opt.correct { background: var(--success-50); border-color: var(--success); color: #065f46; }
.quiz button.opt.wrong { background: var(--danger-50); border-color: var(--danger); color: #991b1b; }
.quiz .feedback { font-weight: 800; min-height: 1.4em; }
.quiz-done { margin-top: 10px; background: var(--accent-50); border: 2px solid #fde68a; border-radius: 12px; padding: 12px 14px; font-size: 1rem; }
.lesson h2[id], .lesson h3[id], .lesson section[id], .lesson div[id], main section[id], body > section[id], section.hero[id] { scroll-margin-top: 90px; }
.btn:disabled, button.opt:disabled { cursor: default; opacity: 0.85; }
.pager { display: flex; justify-content: space-between; gap: 12px; margin-top: 28px; flex-wrap: wrap; }
.progress-wrap { position: sticky; top: 68px; z-index: 40; height: 6px; background: #eef2ff; }
#progress { height: 100%; width: 0; background: linear-gradient(90deg, var(--primary), #8b5cf6); border-radius: 999px; }

/* oblici oblasti */
.oblast { border: 1px solid var(--line); background: #fff; border-radius: var(--radius); padding: 18px; box-shadow: var(--shadow-sm); }
.oblast h3 { margin: 0 0 6px; }
.oblast ol { margin: 8px 0 0; padding-left: 20px; display: grid; gap: 4px; }
.oblast li a { font-weight: 700; }
.pill { display: inline-block; font-size: 0.8rem; font-weight: 900; background: var(--ink); color: #fff; border-radius: 999px; padding: 3px 10px; margin-right: 8px; }

/* footer */
footer { margin-top: 48px; border-top: 1px solid var(--line); background: #fff; padding: 28px 0; color: var(--muted); font-size: 0.95rem; }
.footer-grid { display: flex; gap: 24px; justify-content: space-between; flex-wrap: wrap; }

/* number line */
.numline { width: 100%; height: 90px; background: #fff; border: 2px solid var(--line); border-radius: 12px; }

/* responsive */
@media (max-width: 900px) {
  .hero-grid { grid-template-columns: 1fr; }
  .grid.cols-3 { grid-template-columns: 1fr; }
  .grid.cols-2 { grid-template-columns: 1fr; }
  .lesson-layout { grid-template-columns: 1fr; }
  .toc { position: static; }
  .nav { display: none; }
  .nav.open { display: flex; position: absolute; top: 68px; left: 0; right: 0; background: #fff; border-bottom: 1px solid var(--line); padding: 12px 20px; flex-wrap: wrap; }
  .hamburger { display: block; }
  .search-box { margin-left: auto; }
  .search-toggle { display: block; }
  .search-input {
    position: absolute; top: 50%; right: 44px; transform: translateY(-50%);
    width: 0; padding: 0; border-width: 0; opacity: 0; pointer-events: none;
    transition: width 0.18s ease, opacity 0.18s ease, padding 0.18s ease;
  }
  .search-box.open .search-input {
    width: 54vw; max-width: 230px; padding: 9px 14px; border-width: 2px; opacity: 1; pointer-events: auto;
  }
  .search-results { right: 0; width: 92vw; }
}
@media print {
  .site-header, .toc, .pager, .hero-actions, footer, .progress-wrap { display: none !important; }
  .lesson { border: 0; box-shadow: none; }
}
/* mobilni prikaz lekcija: tabele ne smiju širiti raspored van ekrana */
@media (max-width: 900px) {
  .lesson-layout > * { min-width: 0; }
  .pv-table { display: block; overflow-x: auto; }
  .pv-table th, .pv-table td { padding: 8px 4px; }
  .pv-table td.big { font-size: 1.2rem; }
}

/* Ujednačen izgled portala i pregleda svih razreda. */
@media screen {
  .site-header { box-shadow: 0 3px 18px rgba(15, 23, 42, 0.03); }
  .nav a.active { background: var(--primary-50); color: var(--primary-600); }
  .card, .oblast { box-shadow: 0 4px 18px rgba(15, 23, 42, 0.035); }
  .card { padding: 26px; gap: 14px; }
  .card:hover { border-color: #c7d2fe; box-shadow: var(--shadow); }
  .card .go, .oblast .go { display: inline-flex; align-items: center; min-height: 44px; font-weight: 800; }
  .grade-overview { padding-bottom: 24px; }
  .grade-intro { display: flex; align-items: center; gap: 24px; padding: 32px; margin-top: 22px; border: 1px solid #dfe3f4; border-radius: 24px; background: linear-gradient(120deg, var(--primary-50), #fff 80%); }
  .grade-intro .grade-number { width: 76px; height: 76px; border-radius: 22px; font-size: 2.25rem; flex-shrink: 0; }
  .grade-meta { color: var(--primary-600); font-size: 0.85rem; font-weight: 800; }
  .grade-intro h1 { margin: 6px 0 8px; font-size: clamp(1.65rem, 3vw, 2.4rem); line-height: 1.2; letter-spacing: -0.035em; }
  .grade-intro p { margin: 0; color: #475569; max-width: 65ch; }
  .grade-overview .oblast { display: flex; flex-direction: column; align-items: flex-start; padding: 26px; min-width: 0; }
  .grade-overview .pill { background: var(--primary-50); color: var(--primary-600); border-radius: 9px; margin: 0 0 14px; }
  .grade-overview .oblast h3 { font-size: 1.22rem; line-height: 1.35; }
  .grade-overview .oblast p { color: #475569; margin: 4px 0 12px; font-size: 0.96rem; }
  .grade-overview .oblast ol { width: 100%; padding-left: 24px; margin: 0 0 16px; gap: 0; }
  .grade-overview .oblast li { padding: 7px 0 7px 4px; border-bottom: 1px solid #f0f2f6; font-size: 0.94rem; }
  .grade-overview .oblast li::marker { color: var(--muted); font-size: 0.8rem; }
  .grade-overview .oblast li a { color: #334155; }
  .grade-overview .oblast li a:hover { color: var(--primary); }
  .grade-overview .oblast .go { margin-top: auto; }
  .lesson-layout > *, .hero-grid > * { min-width: 0; }
  .lesson h1 { letter-spacing: -0.025em; }
  .toc { box-shadow: none; }
  .toc a { display: inline-block; padding: 3px 0; }
  a:focus-visible, button:focus-visible, input:focus-visible, select:focus-visible { outline: 3px solid var(--primary); outline-offset: 4px; }
}
@media screen and (max-width: 900px) {
  .grade-intro { align-items: flex-start; gap: 16px; padding: 24px 20px; }
  .grade-intro .grade-number { width: 48px; height: 48px; border-radius: 15px; font-size: 1.5rem; }
  .grade-overview .oblast { padding: 22px; }
  .grade-intro h1 { overflow-wrap: anywhere; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .card, .btn { transition: none; }
  .step.visible { animation: none; }
}
@media screen {
  .lesson .formula { max-width: 100%; overflow-x: auto; }
  .lesson { overflow-wrap: anywhere; }
}

/* Riješeni zadaci: matematički zapis i komentar u istom redu sveske. */
.worked-example { margin-block: 24px; }
.notebook.steps { gap: 0; padding: 8px 16px; border: 1px solid var(--line); border-radius: 12px; background: #fff; }
.notebook .notebook-row { border: 0; border-radius: 0; margin: 0; padding: 14px 0; background: transparent; border-bottom: 1px solid #dce8f5; box-shadow: none; }
.notebook .notebook-row.visible { display: grid; grid-template-columns: minmax(0, 1.6fr) minmax(0, 1fr); gap: 24px; align-items: baseline; }
.notebook-math { min-width: 0; font-size: 1.12rem; font-weight: 700; color: var(--ink); font-variant-numeric: tabular-nums; line-height: 1.9; overflow-wrap: anywhere; }
.notebook-note { min-width: 0; padding-left: 16px; border-left: 2px solid #f4c9d0; color: #526175; font-size: .91rem; line-height: 1.65; }
.notebook-math:has(> .notebook-sign) { display: grid; grid-template-columns: minmax(0, 1.4fr) auto minmax(0, 1.6fr); column-gap: .45em; }
.notebook-lhs { text-align: right; }
.notebook .controls { align-items: center; padding-top: 8px; }
.notebook [data-count] { color: var(--muted); font-size: .85rem; }
@media (max-width: 900px) {
  .notebook.steps { padding-inline: 12px; }
  .notebook .notebook-row.visible { grid-template-columns: minmax(0, 1fr); gap: 5px; }
  .notebook-note { padding-left: 10px; }
}
@media print {
  .notebook .notebook-row.step { display: grid !important; grid-template-columns: minmax(0, 1.6fr) minmax(0, 1fr); gap: 20px; break-inside: avoid; animation: none; }
  .notebook .controls { display: none !important; }
  .worked-example { box-shadow: none; }
}
/* Pismeni račun: razmaci čuvaju poravnanje cifara po mjesnoj vrijednosti. */
.notebook-math pre, .notebook-written { margin: 0; max-width: 100%; overflow-x: auto; white-space: pre; font: inherit; font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, 'DejaVu Sans Mono', monospace; font-variant-numeric: tabular-nums lining-nums; line-height: 1.65; }
@media (max-width: 900px) {
  .notebook-math:has(> .notebook-sign) { display: block; }
  .notebook-sign { padding-inline: .3em; }
  .notebook-lhs { text-align: left; }
}
@media print {
  [data-steps] .controls, [data-steps] .step-nav { display: none !important; }
}


/* Keep drawing surfaces inside narrow lesson columns; preserve their aspect ratio. */
.viz, .viz-canvas { min-width: 0; }
.viz-canvas > svg, .viz-canvas > canvas { max-width: 100%; height: auto; }
.viz .control { max-width: 100%; min-width: 0; }
.viz .control input[type="range"] { max-width: 100%; }
svg[data-fit-svg] { width: 100%; max-width: 420px; height: 260px; }

/* On small screens, spend width on the lesson instead of nested card frames. */
@media screen and (max-width: 900px) {
  .container { padding-inline: 12px; }
  .lesson-layout { gap: 16px; }
  .lesson { padding: 14px 0; border: 0; border-radius: 0; box-shadow: none; background: transparent; }
  .toc { padding: 12px; border-radius: 12px; }
  .lesson .viz, .lesson .callout, .lesson .quiz { padding: 12px 10px; border-width: 1px; border-radius: 12px; }
  .lesson .example { padding: 12px 10px; border-left-width: 3px; }
  .lesson .worked-example { padding-inline: 8px; }
  .lesson .worked-example .notebook.steps { padding: 0; border: 0; border-radius: 0; background: transparent; }
  .lesson .notebook.steps { padding-inline: 8px; }
  .lesson .notebook-note { padding-left: 8px; border-left-width: 1px; }
  .lesson .formula { padding: 12px 8px; }
  .lesson .viz-canvas { padding-inline: 0; }
  .lesson .controls, .lesson .step-nav { gap: 8px; }
  .lesson .controls .btn, .lesson .step-nav .btn, .quiz button.opt { min-height: 44px; }
  .lesson .controls .btn { max-width: 100%; white-space: normal; }
  .lesson .quiz-done { padding: 10px; border-width: 1px; }
  .card, .grade-overview .oblast { padding: 16px; }
  .grade-intro { padding: 18px 14px; }
}
@media screen and (max-width: 900px) {
  .header-inner { gap: 8px; }
  .logo { gap: 6px; font-size: 1.15rem; }
  .logo-mark { width: 32px; height: 32px; flex-shrink: 0; }
  .hamburger { margin-left: 0; min-width: 44px; min-height: 44px; padding: 6px 10px; flex-shrink: 0; }
  .search-box { flex-shrink: 0; }
}

/* Design study: isolated to /dizajn/. Existing lessons keep their design. */
.design-poc { --font: 'Inter', system-ui, sans-serif; --primary: #245c48; --primary-600: #194535; --primary-50: #edf2eb; --ink: #252d29; --muted: #656b64; --line: #d9ddd3; --bg: #f5f3ec; background: var(--bg); font-weight: 400; }
.design-poc .site-header { background: var(--bg); backdrop-filter: none; box-shadow: none; }
.design-poc .logo { font-family: 'Inter', sans-serif; font-size: 1.12rem; letter-spacing: -.045em; }
.design-poc .logo-mark { border-radius: 0; background: transparent; color: var(--primary); font-family: Georgia, serif; font-size: 2rem; box-shadow: none; }
.design-poc .logo small { font-size: .65rem; letter-spacing: .03em; }
.design-poc .nav a { font-size: .78rem; font-weight: 500; border-radius: 3px; }
.design-poc .poc-toolbar { position: sticky; top: 68px; z-index: 30; border-bottom: 1px solid var(--line); background: var(--bg); }
.design-poc .poc-toolbar-inner { display: flex; align-items: center; justify-content: space-between; gap: 16px; min-height: 78px; }
.design-poc .poc-label { font-size: .8rem; font-weight: 700; }
.design-poc .poc-label small { display: block; color: var(--muted); font-size: .68rem; font-weight: 400; }
.design-poc .poc-switch { display: flex; gap: 4px; padding: 4px; border: 1px solid var(--line); border-radius: 6px; }
.design-poc .poc-switch button, .design-poc .poc-focus { font: inherit; font-size: .8rem; cursor: pointer; min-height: 44px; padding: 8px 16px; border: 0; border-radius: 3px; background: transparent; color: var(--ink); }
.design-poc .poc-switch button span { color: var(--muted); margin-right: 7px; font-size: .65rem; }
.design-poc .poc-switch button[aria-pressed="true"] { background: var(--ink); color: #fff; }
.design-poc .poc-switch button[aria-pressed="true"] span { color: #cbd4cd; }
.design-poc .poc-focus { border: 1px solid var(--line); }
.design-poc .poc-focus[aria-pressed="true"] { background: var(--ink); color: white; }
.design-poc .poc-caption { display: flex; justify-content: space-between; gap: 20px; align-items: baseline; padding-block: 16px; font-size: .75rem; color: var(--muted); }
.design-poc .poc-caption p { margin: 0; }
.design-poc .poc-caption a { white-space: nowrap; color: var(--muted); }
.design-poc .breadcrumb { font-size: .72rem; margin-block: 16px 30px; }
.design-poc .lesson { padding: 0 0 60px; background: transparent; border: 0; box-shadow: none; border-radius: 0; min-width: 0; }
.design-poc .poc-lesson-head { display: grid; grid-template-columns: minmax(0, 1fr) 200px; gap: 20px; align-items: center; padding: 10px 0 34px; border-bottom: 1px solid var(--ink); margin-bottom: 28px; }
.design-poc .poc-eyebrow { font: 600 .65rem/1.6 'Inter', sans-serif; letter-spacing: .12em; color: var(--primary); margin: 0 0 20px; }
.design-poc .lesson h1 { font-size: clamp(2.7rem, 5.5vw, 4.5rem); font-weight: 400; letter-spacing: -.055em; line-height: 1.04; margin: 0 0 24px; }
.design-poc .poc-period { color: var(--primary); }
.design-poc .poc-lead { font-size: 1rem; color: var(--muted); line-height: 1.7; margin-bottom: 22px; }
.design-poc .poc-meta { display: flex; gap: 12px; align-items: center; font: 500 .65rem 'Inter',sans-serif; text-transform: uppercase; letter-spacing: .1em; }
.design-poc .poc-meta i { width: 3px; height: 3px; background: var(--primary); border-radius: 50%; }
.design-poc .poc-hero-drawing { width: 100%; color: var(--primary); font: italic 18px Georgia,serif; }
.design-poc .poc-drawing-caption { font-size: 16px; }
.design-poc .lesson h2 { font-size: 1.65rem; line-height: 1.3; font-weight: 500; letter-spacing: -.025em; border-top: 1px solid var(--line); padding-top: 28px; margin-top: 42px; }
.design-poc .lesson h3 { font-size: 1.15rem; font-weight: 600; }
.design-poc .lesson h4 { font-weight: 600; }
.design-poc .lesson p, .design-poc .lesson li { line-height: 1.8; }
.design-poc .callout { border: 0; border-left: 2px solid var(--primary); padding: 12px 20px; border-radius: 0; background: transparent; }
.design-poc .callout.goal { background: var(--primary-50); padding: 22px 24px; }
.design-poc .callout.warn { border-color: #aa6944; background: #f5eee4; }
.design-poc .callout > b, .design-poc .callout .title { font: 600 .8rem 'Inter',sans-serif; }
.design-poc .formula { background: transparent; color: var(--ink); border-block: 1px solid var(--line); border-radius: 0; padding: 22px 10px; font-family: Georgia,serif; font-size: 1.6rem; font-weight: 400; letter-spacing: 0; }
.design-poc .viz { padding: 26px; background: #fff; border: 1px solid var(--line); border-radius: 4px; }
.design-poc .viz h4 { margin-bottom: 12px; }
.design-poc .viz p.hint { font-size: .87rem; }
.design-poc .btn { border-radius: 3px; font-weight: 500; font-size: .78rem; box-shadow: none; min-height: 44px; padding: 10px 14px; }
.design-poc .btn:hover { transform: none; }
.design-poc .btn.secondary { background: transparent; color: var(--ink); border: 1px solid var(--line); }
.design-poc .control { font-size: .8rem; font-weight: 500; }
.design-poc .control output { background: var(--primary-50); color: var(--primary); border-radius: 2px; }
.design-poc .control input[type="range"] { accent-color: var(--primary); }
.design-poc .example { border: 0; border-top: 1px solid var(--line); background: transparent; border-radius: 0; padding: 20px 0; }
.design-poc .notebook.steps { border: 0; border-radius: 0; padding: 0 14px; background: #fff; }
.design-poc .notebook-math { font-family: Georgia,serif; font-size: 1.25rem; font-weight: 400; }
.design-poc .notebook-note { font-size: .8rem; border-color: var(--line); }
.design-poc .quiz { border: 1px solid var(--line); border-radius: 3px; padding: 24px; }
.design-poc .quiz button.opt { font-weight: 500; border-width: 1px; border-radius: 3px; min-height: 44px; }
.design-poc .quiz .q { font-weight: 600; }
.design-poc .quiz-done { border-width: 1px; border-radius: 3px; }
.design-poc .toc { top: 170px; padding: 20px 0; background: transparent; border: 0; border-radius: 0; box-shadow: none; font-size: .78rem; }
.design-poc .toc > b { text-transform: uppercase; letter-spacing: .1em; font-size: .65rem; font-weight: 600; }
.design-poc .toc ul { list-style: none; padding: 0; margin-top: 18px; }
.design-poc .toc li { border-bottom: 1px solid var(--line); }
.design-poc .toc a { padding: 11px 0; color: var(--muted); line-height: 1.5; }
.design-poc .toc a:hover { color: var(--primary); }
.design-poc .lesson h2[id], .design-poc .lesson h3[id], .design-poc section[id], .design-poc #greske { scroll-margin-top: 175px; }
/* 01 / Editorial rhythm: a single reading column, chapter index above. */
.design-poc[data-look="paper"] .lesson-layout { display: block; max-width: 820px; margin: auto; }
.design-poc[data-look="paper"] .lesson { font-family: Georgia, 'Times New Roman', serif; font-size: 1.1rem; }
.design-poc[data-look="paper"] .toc { position: static; padding: 0 0 22px; border-bottom: 1px solid var(--line); margin-bottom: 30px; }
.design-poc[data-look="paper"] .toc ul { display: flex; flex-wrap: wrap; gap: 4px 20px; margin: 10px 0 0; }
.design-poc[data-look="paper"] .toc li { border: 0; }
.design-poc[data-look="paper"] .toc a { padding: 5px 0; }
.design-poc[data-look="paper"] .lesson h1, .design-poc[data-look="paper"] .lesson h2 { font-family: Georgia,serif; }
/* 02 / Atlas: strong geometry, open grid, ink blue and square edges. */
.design-poc[data-look="atlas"] { --bg: #fff; --ink: #132d4a; --primary: #164fbd; --primary-600: #123d91; --primary-50: #edf3fd; --muted: #53657a; --line: #ccd7e4; }
.design-poc[data-look="atlas"] .lesson-layout { grid-template-columns: 190px minmax(0,1fr); gap: 54px; }
.design-poc[data-look="atlas"] .poc-lesson-head { border-bottom: 3px solid var(--ink); }
.design-poc[data-look="atlas"] .lesson h1 { font-weight: 600; font-size: clamp(2.8rem, 5.5vw, 4.7rem); }
.design-poc[data-look="atlas"] .poc-hero-drawing { background-image: linear-gradient(#164fbd0b 1px,transparent 1px),linear-gradient(90deg,#164fbd0b 1px,transparent 1px); background-size: 20px 20px; }
.design-poc[data-look="atlas"] .lesson h2 { border-top-color: var(--ink); font-weight: 600; }
.design-poc[data-look="atlas"] .viz { border: 0; border-left: 3px solid var(--primary); border-radius: 0; background: #f4f7fc; }
.design-poc[data-look="atlas"] .formula { text-align: left; border: 0; border-left: 3px solid var(--primary); padding-left: 22px; color: var(--primary); }
.design-poc[data-look="atlas"] .callout.goal { background: transparent; border: 1px solid var(--line); }
/* 03 / Desk: persistent rail and white working sheet. */
.design-poc[data-look="desk"] { --bg: #edf0f1; --ink: #263336; --primary: #176963; --primary-600: #11524d; --primary-50: #e8f2ef; --muted: #627175; --line: #d6dfe0; }
.design-poc[data-look="desk"] .lesson-layout { grid-template-columns: 220px minmax(0,1fr); gap: 30px; }
.design-poc[data-look="desk"] .lesson { background: white; padding: 38px; border: 1px solid var(--line); border-radius: 3px; }
.design-poc[data-look="desk"] .toc { padding: 22px; background: #263336; color: #fff; border-radius: 3px; }
.design-poc[data-look="desk"] .toc a { color: #d8e3e3; }
.design-poc[data-look="desk"] .toc li { border-color: #435053; }
.design-poc[data-look="desk"] .poc-lesson-head { grid-template-columns: minmax(0,1fr) 130px; }
.design-poc[data-look="desk"] .lesson h1 { font-size: clamp(2.6rem,4vw,3.5rem); font-weight: 500; }
.design-poc[data-look="desk"] .viz { background: #f5f8f7; }
.design-poc[data-look="desk"] .worked-example { padding: 20px 16px; border: 1px solid var(--line); background: #fbfcfc; margin-block: 20px; }
.design-poc[data-look="desk"] .notebook.steps { padding: 0; }
.design-poc[data-look="desk"] .notebook .notebook-row { border-bottom-color: #d8e3eb; }
.design-poc.poc-focused .toc, .design-poc.poc-focused .breadcrumb, .design-poc.poc-focused .poc-caption { display: none; }
.design-poc.poc-focused .lesson-layout { display: block; max-width: 820px; margin: 30px auto; }
@media screen and (max-width: 900px) {
  .design-poc .poc-toolbar-inner { flex-wrap: wrap; gap: 6px; padding-block: 9px; }
  .design-poc .poc-label { flex: 1; font-size: .72rem; }
  .design-poc .poc-label small { display: none; }
  .design-poc .poc-switch { order: 3; width: 100%; padding: 2px; }
  .design-poc .poc-switch button { flex: 1; padding: 8px 4px; font-size: .74rem; }
  .design-poc .poc-switch button span { margin-right: 3px; }
  .design-poc .poc-focus { min-height: 36px; font-size: .7rem; padding: 4px 12px; }
  .design-poc .poc-caption { display: block; font-size: .72rem; padding-block: 12px; }
  .design-poc .poc-caption a { display: inline-block; margin-top: 8px; }
  .design-poc[data-look] .lesson-layout { display: block; }
  .design-poc[data-look] .toc { position: static; margin-bottom: 24px; padding: 14px 0; }
  .design-poc[data-look] .toc ul { display: flex; flex-wrap: wrap; gap: 4px 14px; margin: 10px 0 0; }
  .design-poc[data-look] .toc li { border: 0; }
  .design-poc[data-look] .toc a { font-size: .74rem; padding: 4px 0; }
  .design-poc[data-look="desk"] .toc { padding: 14px; }
  .design-poc[data-look] .lesson { padding: 0 0 30px; border: 0; }
  .design-poc[data-look="desk"] .lesson { background: transparent; }
  .design-poc[data-look] .poc-lesson-head { grid-template-columns: minmax(0,1fr) 95px; gap: 10px; padding-bottom: 26px; }
  .design-poc[data-look] .lesson h1 { font-size: clamp(2.35rem,8vw,3.4rem); }
  .design-poc .poc-eyebrow { font-size: .55rem; letter-spacing: .06em; }
  .design-poc .poc-lead { font-size: .87rem; }
  .design-poc .poc-meta { gap: 7px; font-size: .56rem; }
  .design-poc .lesson h2 { font-size: 1.4rem; }
  .design-poc .lesson .viz, .design-poc .lesson .quiz { padding: 16px 10px; }
  .design-poc .lesson .callout.goal { padding: 16px 12px; }
  .design-poc .lesson .notebook.steps { padding-inline: 0; }
  .design-poc .lesson h2[id], .design-poc .lesson h3[id], .design-poc section[id], .design-poc #greske { scroll-margin-top: 205px; }
}
@media (prefers-reduced-motion: no-preference) {
  .design-poc .poc-switch button, .design-poc .poc-focus { transition: background-color .15s ease, color .15s ease; }
}
@media print {
  .design-poc .poc-toolbar, .design-poc .poc-caption, .design-poc .poc-hero-drawing { display: none !important; }
  .design-poc[data-look] { background: white; color: black; }
  .design-poc[data-look] .lesson-layout { display: block; }
  .design-poc[data-look] .lesson { padding: 0; border: 0; background: white; }
}
.design-poc .poc-toc-toggle { display: none; }
@media screen and (max-width: 900px) {
  .design-poc .poc-toc-toggle { display: block; font: 500 .75rem 'Inter',sans-serif; color: var(--primary); background: transparent; border: 0; min-height: 44px; padding: 10px 0; cursor: pointer; }
  .design-poc[data-look="desk"] .poc-toc-toggle { color: #d8e3e3; }
  .design-poc[data-look] .toc:not(.poc-toc-open) ul { display: none; }
}

/* Portal themes: Atlas is the default; classic uses the original design system. */
html[data-theme="atlas"] { --bg: #fff; --ink: #132d4a; --primary: #164fbd; --primary-600: #123d91; --primary-50: #edf3fd; --muted: #53657a; --line: #ccd7e4; --font: 'Inter', system-ui, sans-serif; --radius: 3px; --radius-sm: 3px; --shadow: none; --shadow-sm: none; }
html[data-theme="atlas"] body:not(.design-poc) { font-weight: 400; }
html[data-theme="atlas"] .site-header { background: #fff; backdrop-filter: none; box-shadow: none; }
html[data-theme="atlas"] .logo { font-size: 1.1rem; letter-spacing: -.04em; }
html[data-theme="atlas"] .logo-mark { background: transparent; color: var(--primary); font: 2rem Georgia,serif; box-shadow: none; border-radius: 0; }
html[data-theme="atlas"] .logo small { font-size: .65rem; letter-spacing: .02em; }
html[data-theme="atlas"] .nav { gap: 0; }
html[data-theme="atlas"] .nav a { font-weight: 500; font-size: .75rem; padding: 9px 9px; border-radius: 2px; white-space: nowrap; }
html[data-theme="atlas"] .nav a.active { background: var(--primary-50); color: var(--primary); }
html[data-theme="atlas"] .search-input { width: 150px; border-width: 1px; border-radius: 3px; }
html[data-theme="atlas"] .search-input:focus { width: 150px; }
html[data-theme="atlas"] .search-toggle, html[data-theme="atlas"] .hamburger { border-width: 1px; border-radius: 3px; }
html[data-theme="atlas"] body:not(.design-poc) .lesson-layout { grid-template-columns: 190px minmax(0,1fr); gap: 54px; }
html[data-theme="atlas"] body:not(.design-poc) .lesson { border: 0; padding: 0 0 60px; border-radius: 0; box-shadow: none; background: transparent; }
html[data-theme="atlas"] body:not(.design-poc) .breadcrumb { font-size: .75rem; margin-block: 24px 36px; }
html[data-theme="atlas"] body:not(.design-poc) .lesson h1 { font-size: clamp(2.25rem,4.3vw,3.8rem); line-height: 1.08; letter-spacing: -.05em; font-weight: 600; border-bottom: 3px solid var(--ink); padding-bottom: 30px; margin-bottom: 28px; }
html[data-theme="atlas"] body:not(.design-poc) .lesson h2 { font-size: 1.65rem; font-weight: 600; letter-spacing: -.025em; line-height: 1.3; border-top: 1px solid var(--ink); padding-top: 28px; margin-top: 42px; }
html[data-theme="atlas"] body:not(.design-poc) .lesson h3 { font-size: 1.15rem; font-weight: 600; }
html[data-theme="atlas"] body:not(.design-poc) .lesson h4 { font-weight: 600; }
html[data-theme="atlas"] body:not(.design-poc) .lesson p, html[data-theme="atlas"] body:not(.design-poc) .lesson li { line-height: 1.8; }
html[data-theme="atlas"] body:not(.design-poc) .toc { padding: 20px 0; background: transparent; border: 0; border-radius: 0; box-shadow: none; font-size: .78rem; }
html[data-theme="atlas"] body:not(.design-poc) .toc > b { text-transform: uppercase; letter-spacing: .1em; font-size: .65rem; font-weight: 600; }
html[data-theme="atlas"] body:not(.design-poc) .toc ul { list-style: none; padding: 0; margin-top: 18px; }
html[data-theme="atlas"] body:not(.design-poc) .toc li { border-bottom: 1px solid var(--line); }
html[data-theme="atlas"] body:not(.design-poc) .toc a { padding: 11px 0; color: var(--muted); line-height: 1.5; }
html[data-theme="atlas"] body:not(.design-poc) .callout { border: 0; border-left: 2px solid var(--primary); padding: 12px 20px; border-radius: 0; background: transparent; }
html[data-theme="atlas"] body:not(.design-poc) .callout.goal { border: 1px solid var(--line); padding: 22px 24px; }
html[data-theme="atlas"] body:not(.design-poc) .callout.warn { border-left-color: #aa6944; background: #fcf6ee; }
html[data-theme="atlas"] body:not(.design-poc) .callout .title { font-size: .82rem; font-weight: 600; }
html[data-theme="atlas"] body:not(.design-poc) .formula { background: transparent; color: var(--primary); border: 0; border-left: 3px solid var(--primary); border-radius: 0; padding: 16px 22px; text-align: left; font: 400 1.6rem/1.6 var(--font); font-variant-numeric: lining-nums tabular-nums; letter-spacing: 0; }
html[data-theme="atlas"] body:not(.design-poc) .formula .frac span:first-child { border-color: currentColor; }
html[data-theme="atlas"] body:not(.design-poc) .viz { padding: 26px; background: #f4f7fc; border: 0; border-left: 3px solid var(--primary); border-radius: 0; }
html[data-theme="atlas"] body:not(.design-poc) .viz p.hint { font-size: .87rem; }
html[data-theme="atlas"] body:not(.design-poc) .btn { border-radius: 3px; font-weight: 500; font-size: .8rem; box-shadow: none; min-height: 44px; padding: 10px 14px; }
html[data-theme="atlas"] body:not(.design-poc) .btn:hover { transform: none; }
html[data-theme="atlas"] body:not(.design-poc) .btn.secondary { background: transparent; color: var(--ink); border: 1px solid var(--line); }
html[data-theme="atlas"] body:not(.design-poc) .control { font-size: .82rem; font-weight: 500; }
html[data-theme="atlas"] body:not(.design-poc) .control output { background: var(--primary-50); color: var(--primary); border-radius: 2px; }
html[data-theme="atlas"] body:not(.design-poc) .example { border: 0; border-top: 1px solid var(--line); background: transparent; border-radius: 0; padding: 20px 0; }
html[data-theme="atlas"] body:not(.design-poc) .notebook.steps { border: 0; border-radius: 0; padding: 0 14px; background: #fff; }
html[data-theme="atlas"] body:not(.design-poc) .notebook-math { font-family: var(--font); font-weight: 500; font-size: 1.25rem; font-variant-numeric: lining-nums tabular-nums; }
html[data-theme="atlas"] body:not(.design-poc) .notebook-math pre, html[data-theme="atlas"] body:not(.design-poc) .notebook-written { font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, 'DejaVu Sans Mono', monospace; font-weight: 500; font-size: 1.1rem; }
html[data-theme="atlas"] body:not(.design-poc) .notebook-note { font-size: .82rem; border-color: var(--line); }
html[data-theme="atlas"] body:not(.design-poc) .quiz { border: 1px solid var(--line); border-radius: 3px; padding: 24px; }
html[data-theme="atlas"] body:not(.design-poc) .quiz button.opt { font-weight: 500; border-width: 1px; border-radius: 3px; min-height: 44px; }
html[data-theme="atlas"] body:not(.design-poc) .quiz .q { font-weight: 600; }
html[data-theme="atlas"] body:not(.design-poc) .quiz-done { border-width: 1px; border-radius: 3px; }
/* Overview pages use the same restrained geometry as lessons. */
html[data-theme="atlas"] body:not(.design-poc) .hero { background: transparent; }
html[data-theme="atlas"] body:not(.design-poc) .hero h1 { font-weight: 600; letter-spacing: -.05em; }
html[data-theme="atlas"] body:not(.design-poc) .card, html[data-theme="atlas"] body:not(.design-poc) .oblast { border-radius: 3px; box-shadow: none; background: white; border: 1px solid var(--line); }
html[data-theme="atlas"] body:not(.design-poc) .card:hover { box-shadow: none; border-color: var(--primary); transform: none; }
html[data-theme="atlas"] body:not(.design-poc) .grade-intro { background: transparent; border: 0; border-bottom: 3px solid var(--ink); border-radius: 0; padding: 24px 0; }
html[data-theme="atlas"] body:not(.design-poc) .grade-number { background: var(--primary-50); color: var(--primary); border-radius: 2px; box-shadow: none; }
html[data-theme="atlas"] body:not(.design-poc) .pill { border-radius: 2px; }
@media screen and (max-width: 900px) {
  html[data-theme="atlas"] .search-input { width: 0; }
  html[data-theme="atlas"] .search-input:focus { width: 0; }
  html[data-theme="atlas"] .search-box.open .search-input { width: 54vw; }
  html[data-theme="atlas"] body:not(.design-poc) .lesson-layout { display: block; }
  html[data-theme="atlas"] body:not(.design-poc) .lesson { padding: 0 0 30px; }
  html[data-theme="atlas"] body:not(.design-poc) .toc { padding: 12px 0; margin-bottom: 24px; }
  html[data-theme="atlas"] body:not(.design-poc) .toc ul { display: flex; flex-wrap: wrap; gap: 4px 16px; }
  html[data-theme="atlas"] body:not(.design-poc) .toc li { border: 0; }
  html[data-theme="atlas"] body:not(.design-poc) .toc a { padding: 5px 0; }
  html[data-theme="atlas"] body:not(.design-poc) .lesson h1 { font-size: clamp(2rem,7.5vw,3rem); padding-bottom: 22px; }
  html[data-theme="atlas"] body:not(.design-poc) .lesson h2 { font-size: 1.4rem; }
  html[data-theme="atlas"] body:not(.design-poc) .viz, html[data-theme="atlas"] body:not(.design-poc) .quiz { padding: 16px 10px; }
  html[data-theme="atlas"] body:not(.design-poc) .callout.goal { padding: 16px 12px; }
  html[data-theme="atlas"] body:not(.design-poc) .notebook.steps { padding-inline: 0; }
  html[data-theme="atlas"] body:not(.design-poc) .formula { padding: 12px 10px; }
}
@media print {
  html[data-theme="atlas"] body:not(.design-poc) .lesson-layout { display: block; }
  html[data-theme="atlas"] body:not(.design-poc) .lesson { padding: 0; }
}
/* Keep the full navigation usable on compact desktop widths. */
@media screen and (min-width: 901px) and (max-width: 1199px) {
  .header-inner { gap: 10px; }
  .header-inner .logo { font-size: 1rem; gap: 6px; }
  .header-inner .nav { gap: 0; }
  .header-inner .nav a { font-size: .7rem; padding: 9px 6px; }
  .header-inner .search-box { margin-left: 4px; }
  .header-inner .search-input, .header-inner .search-input:focus { width: 105px; }
}
html[data-theme="atlas"] body:not(.design-poc) svg [stroke="#4f46e5"],
html[data-theme="atlas"] body:not(.design-poc) svg [stroke="#4338ca"] { stroke: var(--primary); }
html[data-theme="atlas"] body:not(.design-poc) svg [fill="#4f46e5"],
html[data-theme="atlas"] body:not(.design-poc) svg [fill="#4338ca"] { fill: var(--primary); }
html[data-theme="atlas"] body:not(.design-poc) svg [fill="#eef2ff"] { fill: var(--primary-50); }
html[data-theme="atlas"] body:not(.design-poc) .hero h1 span { background: none; color: var(--primary); }
html[data-theme="atlas"] body:not(.design-poc) .eyebrow { background: transparent; border: 0; border-radius: 0; padding-inline: 0; font-size: .75rem; font-weight: 500; }
html[data-theme="atlas"] body:not(.design-poc) .hero-card { border-radius: 0; background: #f4f7fc; color: var(--ink); border-left: 3px solid var(--primary); box-shadow: none; }
html[data-theme="atlas"] body:not(.design-poc) .hero-card::after { display: none; }
html[data-theme="atlas"] body:not(.design-poc) .mini-list li { background: transparent; border: 0; border-bottom: 1px solid var(--line); border-radius: 0; padding-inline: 0; }
html[data-theme="atlas"] body:not(.design-poc) .stat { border: 0; border-left: 1px solid var(--line); border-radius: 0; box-shadow: none; }
html[data-theme="atlas"] body:not(.design-poc) .card .tag { border-radius: 2px; font-weight: 600; }
@media screen and (min-width: 901px) and (max-width: 1199px) {
  html[data-theme="atlas"] .header-inner .search-input,
  html[data-theme="atlas"] .header-inner .search-input:focus { width: 105px; }
}
@media screen and (max-width: 900px) {
  .section h1, .section h2, .card h3, .oblast h3 { overflow-wrap: anywhere; }
}
@media screen and (max-width: 900px) {
  .container h1, .container h2 { overflow-wrap: anywhere; }
}

/* Interactive explorers: controls and drawings own separate, stable rows.
   Flex intrinsic sizing previously let changing result text resize the SVG. */
.controls.viz-explorer {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  align-items: start;
  gap: 12px;
}
.viz-explorer > label { min-width: 0; }
.viz-explorer output { display: inline-block; min-width: 5ch; font-variant-numeric: tabular-nums; }
.viz-explorer > input[type="range"] { width: 100%; min-width: 0; margin-inline: 0; }
.viz-explorer > #diagram { width: 100%; min-width: 0; }
.viz-explorer > #diagram > svg { display: block; width: 100%; height: auto; margin-inline: auto; }
.viz-explorer .angle-relations { min-height: 5.4em; font-variant-numeric: tabular-nums; }
.viz-explorer .angle-relations p { margin: 0; }

/* Presentation POC: separate reading surface, shared portal assets. */
.presentation-page { background: #fff; color: #132d4a; font-family: Inter, sans-serif; }
.presentation-page [hidden] { display: none !important; }
.presentation-page button, .presentation-page summary { cursor: pointer; }
.presentation-page button { font: inherit; color: inherit; background: #fff; border: 1px solid #ccd5df; border-radius: 4px; padding: 10px 18px; min-height: 44px; }
.presentation-page button:focus-visible, .presentation-page a:focus-visible, .presentation-page summary:focus-visible { outline: 3px solid #164fbd; outline-offset: 3px; }
.presentation-page button:disabled { opacity: .4; cursor: default; }
.presentation-page [data-presentation] { min-height: 100vh; min-height: 100dvh; display: flex; flex-direction: column; background: #fff; }
.presentation-header { display: flex; align-items: center; justify-content: space-between; gap: 12px; padding: 15px 4vw; border-bottom: 1px solid #e1e6ec; font-size: 13px; }
.presentation-header a { color: inherit; text-decoration: none; }
.presentation-header > span { font-weight: 600; }
.presentation-stage { flex: 1; display: grid; align-items: center; width: min(1120px, 92%); margin: 0 auto; padding: 28px 0; }
.presentation-slide { min-width: 0; animation: presentation-appear .16s ease-out; }
.presentation-slide h1 { font-size: clamp(30px, 4.2vw, 58px); line-height: 1.12; letter-spacing: -.04em; margin: 0 0 28px; color: inherit; border: 0; padding: 0; overflow-wrap: anywhere; }
.presentation-slide h1:focus { outline: none; }
.presentation-slide p { font-size: clamp(17px, 1.8vw, 23px); line-height: 1.6; max-width: 900px; }
.presentation-slide .presentation-eyebrow { color: #164fbd; font-size: 12px; letter-spacing: .14em; text-transform: uppercase; font-weight: 700; margin: 0 0 18px; }
.presentation-slide .presentation-lead { font-size: clamp(23px, 2.7vw, 36px); line-height: 1.4; }
.presentation-slide svg { display: block; width: 100%; max-width: 600px; max-height: 300px; margin: 0 auto; }
.presentation-page:not(.presentation-active) .presentation-slide svg text { font: 25px Georgia, serif; fill: currentColor; }
.presentation-split { display: grid; grid-template-columns: 1.4fr 1fr; gap: 40px; align-items: center; }
.presentation-slide .viz { margin: 0; padding: 12px; background: #f5f8fc; border: 0; }
.presentation-slide input[type="range"] { display: block; width: 100%; margin: 24px 0; accent-color: #164fbd; }
.presentation-slide output { font-variant-numeric: tabular-nums; }
.presentation-slide .presentation-readout { font-size: 32px; font-variant-numeric: tabular-nums; min-height: 2.8em; }
.presentation-equation { font: clamp(30px, 5vw, 64px)/1.7 Georgia, serif; color: #164fbd; padding: 14px 0; }
.presentation-work.example { border: 0; background: transparent; padding: 0; margin: 25px 0; min-height: 310px; }
.presentation-row { display: grid; grid-template-columns: 1fr 1fr; gap: 26px; align-items: baseline; padding: 12px 0; border-bottom: 1px solid #e5eaf0; }
.presentation-row > span { font: clamp(23px, 3vw, 37px)/1.3 Georgia, serif; }
.presentation-row small { font-size: 16px; color: #506176; }
.presentation-slide details { margin: 16px 0; }
.presentation-slide .quiz { border: 0; background: none; padding: 0; }
.presentation-options { display: flex; flex-wrap: wrap; gap: 16px; margin: 24px 0; }
.presentation-options button.opt { font-size: 26px; min-width: 130px; }
.presentation-slide .presentation-hint { font-size: 15px; color: #506176; }
.presentation-summary p { display: flex; justify-content: space-between; gap: 24px; border-bottom: 1px solid #e1e6ec; padding: 16px 0; }
.presentation-nav { display: flex; justify-content: space-between; gap: 8px; width: min(1120px,92%); margin: 0 auto; padding-top: 16px; border-top: 1px solid #e1e6ec; }
.presentation-page [data-present-next] { background: #164fbd; color: white; border-color: #164fbd; }
.presentation-page [data-present-count] { font-variant-numeric: tabular-nums; margin-left: 8px; }
.presentation-help { text-align: center; font-size: 12px; color: #506176; margin: 13px 12px 18px; }
.presentation-overview { position: fixed; inset: 80px 4vw 90px; z-index: 20; background: white; border: 1px solid #ccd5df; box-shadow: 0 15px 70px #132d4a22; padding: 24px; overflow: auto; display: grid; grid-template-columns: repeat(3,minmax(0,1fr)); gap: 14px; align-content: start; }
.presentation-overview button { text-align: left; }
.presentation-overview button[aria-current="step"] { border: 2px solid #164fbd; background: #edf3fd; }
@keyframes presentation-appear { from { opacity: .4; } to { opacity: 1; } }
@media(max-width:900px) {
 .presentation-header { padding: 10px 4%; flex-wrap: wrap; }
 .presentation-header > span { order: 3; width: 100%; }
 .presentation-stage { padding: 28px 0; }
 .presentation-split { grid-template-columns: 1fr; gap: 14px; }
 .presentation-row { grid-template-columns: 1fr; gap: 4px; }
 .presentation-work.example { min-height: 360px; }
 .presentation-overview { grid-template-columns: 1fr; inset: 110px 4% 100px; }
 .presentation-nav button { padding: 10px; font-size: 13px; }
 .presentation-options button.opt { min-width: 80px; }
 .presentation-summary p { flex-direction: column; gap: 4px; }
}
@media(prefers-reduced-motion:reduce) { .presentation-slide { animation: none; } }
@media print {
 .presentation-page .presentation-header, .presentation-page .presentation-nav, .presentation-page .presentation-help, .presentation-page .presentation-overview { display: none !important; }
 .presentation-page .presentation-stage { display: block; width: 100%; }
 .presentation-page .presentation-slide[hidden], .presentation-page [data-reveal][hidden] { display: block !important; }
 .presentation-page .presentation-slide { break-after: page; padding: 20px; }
}

/* Portal-wide presentation views reuse the live lesson nodes. */
body.presentation-active > :not(.lesson-presentation) { display: none !important; }
body.presentation-active { margin: 0; }
.presentation-page .lesson-presentation .presentation-stage { width: min(1120px, 92%); }
.presentation-page .lesson-presentation .presentation-slide > h1 { font-size: clamp(28px, 3.6vw, 49px); margin-bottom: 22px; }
.presentation-page .lesson-presentation .presentation-slide :is(p, li, h1, h2, h3, h4, .presentation-equation) { overflow-wrap: anywhere; }
.presentation-page .lesson-presentation .presentation-equation { font-size: clamp(25px, 3.8vw, 48px); white-space: pre-line; }
.presentation-page .lesson-presentation .presentation-key-points { padding-left: 1.2em; font-size: clamp(21px, 2.5vw, 30px); line-height: 1.6; }
.presentation-page .lesson-presentation .presentation-key-points li { margin: 14px 0; }
.presentation-page .lesson-presentation .worked-example { padding: 18px 0; margin: 0; border: 0; background: transparent; }
.presentation-page .lesson-presentation .worked-example > h4 { display: none; }
.presentation-page .lesson-presentation .worked-example > p { font-size: clamp(20px, 2.1vw, 28px); margin: 0 0 24px; }
.presentation-page .lesson-presentation .notebook.steps { min-height: 220px; padding: 0; border: 0; background: none; }
.presentation-page .lesson-presentation .notebook .notebook-row.visible { grid-template-columns: minmax(0, 1.3fr) minmax(0, 1fr); gap: 24px; padding: 12px 0; }
.presentation-page .lesson-presentation .notebook-math { font: 400 clamp(23px, 2.7vw, 34px)/1.5 Georgia, serif; min-width: 0; }
.presentation-page .lesson-presentation .notebook-note { font-size: 16px; line-height: 1.6; color: #506176; }
.presentation-page .lesson-presentation .notebook-math :is(.notebook-lhs, .notebook-rhs) { overflow-wrap: anywhere; }
.presentation-page .lesson-presentation [data-steps] > :is(.controls, .step-nav) { display: none; }
.presentation-step-tools { display: flex; flex-wrap: wrap; gap: 10px; margin: 20px 0; }
.presentation-page .presentation-step-tools button { font-size: 13px; }
.presentation-page .lesson-presentation .quiz { border: 0; padding: 0; background: transparent; }
.presentation-page .lesson-presentation .quiz .qitem { margin: 0; padding: 0; border: 0; }
.presentation-page .lesson-presentation .quiz .q { font-size: clamp(21px, 2.5vw, 32px); }
.presentation-page .lesson-presentation .quiz button.opt { font-size: clamp(18px, 2vw, 25px); min-height: 50px; white-space: normal; overflow-wrap: anywhere; }
.presentation-page .lesson-presentation .viz { width: 100%; max-width: 100%; margin: 0; padding: 18px; box-sizing: border-box; }
.presentation-page .lesson-presentation .viz svg { height: auto; max-width: 100%; max-height: 390px; }
.presentation-page .lesson-presentation .viz canvas { max-width: 100%; height: auto; }
.presentation-page .lesson-presentation .viz input[type="range"] { margin-block: 12px; }
.presentation-page .lesson-presentation .viz :is(p, .hint) { font-size: 16px; }
.presentation-page .lesson-presentation .viz > :is(h3,h4) { display: none; }
.presentation-page .lesson-presentation .viz .controls { min-width: 0; }
.presentation-page .lesson-presentation table { display: block; max-width: 100%; overflow-x: auto; }
.presentation-page .lesson-presentation .callout { margin: 0; }
.lesson-presentation-link { margin: 12px 0 24px; }
.lesson-presentation-link .btn { font-size: 14px; }
@media(max-width:900px) {
 .presentation-page .lesson-presentation .presentation-stage { width: 92%; }
 .presentation-page .lesson-presentation .notebook .notebook-row.visible { grid-template-columns: minmax(0, 1fr); gap: 5px; }
 .presentation-page .lesson-presentation .notebook-note { font-size: 14px; }
 .presentation-page .lesson-presentation .notebook.steps { min-height: 280px; }
 .presentation-page .lesson-presentation .viz { padding: 12px 6px; }
 .presentation-page .lesson-presentation .viz .controls > * { max-width: 100%; }
 .presentation-page .lesson-presentation .presentation-header > span { overflow-wrap: anywhere; }
}
@media print {
 .presentation-page .lesson-presentation .presentation-step-tools { display: none !important; }
 .presentation-page .lesson-presentation .presentation-slide { break-inside: avoid; }
 .lesson-presentation-link { display: none; }
}

.presentation-catalogue { padding-block: 28px 70px; }
.presentation-catalogue > h1 { font-size: clamp(32px,5vw,64px); letter-spacing: -.04em; margin-bottom: 20px; }
.presentation-catalogue > p { max-width: 720px; font-size: 18px; }
.presentation-catalogue-grades { display: flex; flex-wrap: wrap; gap: 10px; margin: 30px 0 45px; }
.presentation-catalogue-grades a { border: 1px solid var(--line); padding: 10px 18px; min-height: 44px; }
.presentation-catalogue section { scroll-margin-top: 95px; margin-bottom: 50px; }
.presentation-catalogue h2 small { color: var(--muted); font-size: 15px; font-weight: 400; }
.presentation-catalogue-list { display: grid; grid-template-columns: repeat(2,minmax(0,1fr)); gap: 0 35px; list-style: none; padding: 0; }
.presentation-catalogue-list li { min-width: 0; border-bottom: 1px solid var(--line); }
.presentation-catalogue-list a { display: flex; justify-content: space-between; align-items: center; gap: 16px; min-height: 60px; padding-block: 14px; color: var(--ink); overflow-wrap: anywhere; }
.presentation-catalogue-list a:hover { color: var(--primary); }
.presentation-catalogue-list span { color: var(--primary); }
@media(max-width:900px) { .presentation-catalogue-list { grid-template-columns: 1fr; } }
.presentation-page .lesson-presentation .presentation-programme-note { margin: 24px 0 0; padding: 14px 18px; font-size: 15px; line-height: 1.6; }
.presentation-page .lesson-presentation .presentation-programme-note p { margin: 5px 0 0; font-size: 15px; }
.presentation-page .lesson-presentation .worked-example > :is(h3,h4) { display: none; }
@media(min-width:901px) and (max-height:900px) {
 .presentation-page .lesson-presentation.presentation-has-visual .presentation-stage { padding-block: 14px; }
 .presentation-page .lesson-presentation.presentation-has-visual .presentation-eyebrow { margin-bottom: 10px; }
 .presentation-page .lesson-presentation.presentation-has-visual .presentation-slide > h1 { font-size: clamp(28px,3vw,38px); margin-bottom: 14px; }
 .presentation-page .lesson-presentation.presentation-has-visual .viz { padding: 12px; }
 .presentation-page .lesson-presentation.presentation-has-visual .viz svg { max-height: clamp(160px,30dvh,270px); }
 .presentation-page .lesson-presentation.presentation-has-visual .viz :is(p,.hint) { margin-block: 6px; font-size: 14px; }
 .presentation-page .lesson-presentation.presentation-has-visual .presentation-header { padding-block: 10px; }
 .presentation-page .lesson-presentation.presentation-has-visual .presentation-help { margin-block: 8px 10px; }
}
@media print {
 .presentation-page .lesson-presentation .notebook .notebook-row.step { display: grid !important; grid-template-columns: minmax(0,1.3fr) minmax(0,1fr); gap: 20px; }
}

.presentation-page .presentation-nav { padding-bottom: 16px; }


/* Keep presentation chrome small and fit live visuals to the available viewport. */
@media screen {
 .presentation-page [data-presentation] { height: 100vh; height: 100dvh; min-height: 0; overflow: hidden; }
 .presentation-page .presentation-header { flex: 0 0 auto; flex-wrap: nowrap; gap: 12px; padding: 6px 2%; min-height: 44px; box-sizing: border-box; }
 .presentation-page .presentation-header > span { order: initial; width: auto; min-width: 0; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
 .presentation-page .presentation-header > :is(a,button) { flex-shrink: 0; }
 .presentation-page .presentation-header button { padding: 4px 10px; min-height: 36px; font-size: 12px; }
 .presentation-page .presentation-stage,
 .presentation-page .lesson-presentation .presentation-stage { flex: 1 1 0; min-height: 0; width: min(1200px,96%); padding: 12px 0; overflow: auto; overscroll-behavior: contain; align-items: center; align-items: safe center; box-sizing: border-box; }
 .presentation-page .presentation-nav { flex: 0 0 auto; width: min(1200px,96%); padding: 6px 0 max(6px,env(safe-area-inset-bottom)); gap: 6px; }
 .presentation-page .presentation-nav button { min-height: 40px; padding: 6px 12px; font-size: 13px; }
 .presentation-page .presentation-fit-frame { position: relative; width: 100%; }
 .presentation-page .presentation-fit-content { position: absolute; top: 0; left: 0; width: 100%; display: flow-root; transform-origin: top center; }
 .presentation-page .presentation-has-visual .presentation-slide > .presentation-fit-frame h1 { font-size: clamp(24px,2.8vw,36px); margin-bottom: 12px; }
 .presentation-page .presentation-has-visual .presentation-eyebrow { margin-bottom: 8px; }
 .presentation-page .lesson-presentation.presentation-has-visual .presentation-stage { padding-block: 10px; }
 .presentation-page .lesson-presentation.presentation-has-visual .viz { padding: 8px; }
 .presentation-page .lesson-presentation.presentation-has-visual .viz svg { max-height: clamp(160px,38dvh,400px); }
 .presentation-page .presentation-overview { inset: 60px 2% 64px; }
}
@media screen and (max-width:600px) {
 .presentation-page .presentation-header > span { display: none; }
 .presentation-page .presentation-header { font-size: 12px; padding-inline: 2%; }
 .presentation-page .presentation-nav button { padding-inline: 8px; font-size: 12px; }
 .presentation-page .lesson-presentation .presentation-slide > h1 { font-size: 28px; margin-bottom: 16px; }
}
@media print {
 .presentation-page .presentation-fit-frame { height: auto !important; }
 .presentation-page .presentation-fit-content { position: static; transform: none !important; }
}
/* The dice outcomes remain a compact 6 × 6 table in presentation mode. */
.presentation-page .presentation-slide .grid6 { display: grid; grid-template-columns: repeat(6,minmax(0,1fr)); gap: 4px; max-width: 360px; margin: 10px auto; }
.presentation-page .presentation-slide .grid6 .cell { aspect-ratio: auto; min-height: 28px; padding: 3px; font-size: 14px; border: 1px solid #d8e0ec; border-radius: 4px; background: #eef0f6; }
.presentation-page .presentation-slide .grid6 .cell.hit { background: #164fbd; color: #fff; }