/* ============================================================
   JEE Notes v2 — "Modern edtech" design system
   Light default · subject-accented · content-first
   ============================================================ */

:root {
  --font-display: "Bricolage Grotesque", "Outfit", system-ui, sans-serif;
  --font-body: "Outfit", system-ui, -apple-system, sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, monospace;

  /* neutrals — warm paper */
  --bg: #faf8f4;
  --bg-tint: #f1ede3;
  --surface: #ffffff;
  --surface-2: #f6f3ec;
  --ink: #1b1b22;
  --ink-2: #4e4e58;
  --ink-3: #87838f;
  --line: #e9e3d7;
  --line-2: #dcd5c7;

  /* subject palettes */
  --phy: #2563eb;  --phy-soft: #e7effd;
  --chem: #0f9d6b; --chem-soft: #e1f6ee;
  --math: #d9820a; --math-soft: #fcf0d8;
  --brand: #5b53e8; --brand-soft: #ecebfd;

  /* active accent (overridden per subject) */
  --accent: var(--brand);
  --accent-soft: var(--brand-soft);
  --on-accent: #ffffff;

  --r-sm: 9px; --r: 14px; --r-lg: 20px; --r-xl: 28px;
  --shadow-sm: 0 1px 2px rgba(24,24,33,.05), 0 1px 3px rgba(24,24,33,.06);
  --shadow-md: 0 4px 14px -4px rgba(24,24,33,.12), 0 2px 6px -2px rgba(24,24,33,.07);
  --shadow-lg: 0 18px 48px -16px rgba(24,24,33,.22);

  --maxw: 1180px;
  --header-h: 64px;
}

[data-theme="dark"] {
  --bg: #0c0c10;
  --bg-tint: #121219;
  --surface: #15151c;
  --surface-2: #1b1b24;
  --ink: #f3f1ec;
  --ink-2: #b7b7c1;
  --ink-3: #7e7e8a;
  --line: #262630;
  --line-2: #34343f;
  --phy: #6ea8ff;  --phy-soft: #15233c;
  --chem: #34d39e; --chem-soft: #0f2a22;
  --math: #fbbf24; --math-soft: #2c2310;
  --brand: #8b84ff; --brand-soft: #1d1b32;
  --on-accent: #0c0c10;
  --shadow-sm: 0 1px 2px rgba(0,0,0,.4);
  --shadow-md: 0 6px 18px -6px rgba(0,0,0,.6);
  --shadow-lg: 0 22px 54px -18px rgba(0,0,0,.7);
}

[data-subject="physics"]     { --accent: var(--phy);  --accent-soft: var(--phy-soft); }
[data-subject="chemistry"]   { --accent: var(--chem); --accent-soft: var(--chem-soft); }
[data-subject="mathematics"] { --accent: var(--math); --accent-soft: var(--math-soft); }

/* ---------- base ---------- */
* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: calc(var(--header-h) + 16px); }
body {
  margin: 0;
  font-family: var(--font-body);
  color: var(--ink);
  background: var(--bg);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
body::before {
  content: ""; position: fixed; inset: 0; z-index: -1; pointer-events: none;
  background:
    radial-gradient(58rem 30rem at 80% -10%, color-mix(in oklab, var(--accent) 18%, transparent), transparent 60%),
    radial-gradient(44rem 28rem at -10% 2%, color-mix(in oklab, var(--accent) 9%, transparent), transparent 55%);
}
a { color: inherit; text-decoration: none; }
img { max-width: 100%; height: auto; }

.skip-link {
  position: fixed; top: 10px; left: 10px; z-index: 200;
  background: var(--accent); color: var(--on-accent);
  padding: 10px 16px; border-radius: var(--r-sm); font-weight: 600;
  transform: translateY(-150%); transition: transform .2s;
}
.skip-link:focus { transform: translateY(0); }

/* reading progress */
.reading-progress { position: fixed; top: 0; left: 0; right: 0; height: 3px; z-index: 120; background: transparent; }
.reading-progress span { display: block; height: 100%; width: 0; background: linear-gradient(90deg, var(--accent), color-mix(in oklab, var(--accent) 55%, #fff)); transition: width .1s linear; }

/* ---------- header ---------- */
.site-header {
  position: sticky; top: 0; z-index: 100;
  backdrop-filter: saturate(1.4) blur(12px);
  background: color-mix(in oklab, var(--bg) 82%, transparent);
  border-bottom: 1px solid var(--line);
}
.header-inner {
  max-width: var(--maxw); margin: 0 auto; height: var(--header-h);
  padding: 0 22px; display: flex; align-items: center; gap: 22px;
}
.brand { display: flex; align-items: center; gap: 10px; font-family: var(--font-display); }
.brand-mark {
  width: 34px; height: 34px; display: grid; place-items: center;
  border-radius: 10px; background: var(--accent); color: var(--on-accent);
  font-weight: 800; font-size: 13px; letter-spacing: .5px;
  box-shadow: var(--shadow-sm);
}
.brand-text { font-weight: 700; font-size: 19px; letter-spacing: -.02em; }
.brand-text em { color: var(--accent); font-style: normal; }
.primary-nav { display: flex; gap: 4px; margin-left: 6px; }
.nav-link {
  padding: 8px 14px; border-radius: 999px; font-weight: 500; font-size: 15px;
  color: var(--ink-2); transition: color .15s, background .15s;
}
.nav-link:hover { color: var(--ink); background: var(--surface-2); }
.nav-link.is-active { color: var(--accent); background: var(--accent-soft); }
.nav-link[data-subject="physics"].is-active { color: var(--phy); }
.header-actions { margin-left: auto; display: flex; align-items: center; gap: 8px; }
.icon-btn {
  width: 40px; height: 40px; display: grid; place-items: center;
  border: 1px solid var(--line); border-radius: 11px; background: var(--surface);
  color: var(--ink-2); cursor: pointer; transition: all .15s;
}
.icon-btn:hover { color: var(--ink); border-color: var(--line-2); transform: translateY(-1px); }
.theme-toggle .i-moon { display: none; }
[data-theme="dark"] .theme-toggle .i-sun { display: none; }
[data-theme="dark"] .theme-toggle .i-moon { display: block; }

/* ---------- main shell ---------- */
.site-main { max-width: var(--maxw); margin: 0 auto; padding: 0 22px 80px; }

/* ---------- breadcrumb ---------- */
.crumbs { padding: 22px 0 6px; }
.crumbs ol { list-style: none; display: flex; flex-wrap: wrap; gap: 7px; margin: 0; padding: 0; font-size: 13.5px; color: var(--ink-3); }
.crumbs li { display: flex; align-items: center; gap: 7px; }
.crumbs li:not(:last-child)::after { content: "/"; color: var(--line-2); }
.crumbs a:hover { color: var(--accent); }
.crumbs li[aria-current] { color: var(--ink-2); font-weight: 500; }

/* ---------- topic hero ---------- */
.topic-hero { padding: 18px 0 26px; border-bottom: 1px solid var(--line); margin-bottom: 30px; }
.topic-eyebrow { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 12px; margin-bottom: 16px; }
.eyebrow-left { display: flex; align-items: center; gap: 12px; min-width: 0; }
.subject-pill {
  display: inline-flex; align-items: center; gap: 7px;
  padding: 5px 13px; border-radius: 999px; font-size: 13px; font-weight: 600;
  color: var(--accent); background: var(--accent-soft);
  border: 1px solid color-mix(in oklab, var(--accent) 22%, transparent);
}
.subject-pill .dot { width: 7px; height: 7px; border-radius: 50%; background: var(--accent); }
.eyebrow-chapter { font-size: 14px; color: var(--ink-3); font-weight: 500; }
.topic-title {
  font-family: var(--font-display); font-weight: 800; letter-spacing: -.03em;
  font-size: clamp(2.1rem, 5.4vw, 3.4rem); line-height: 1.04; margin: 0 0 14px;
  background: linear-gradient(180deg, var(--ink), color-mix(in oklab, var(--ink) 72%, var(--accent)));
  -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent;
}
.topic-lede { font-size: clamp(1.05rem, 2vw, 1.22rem); color: var(--ink-2); max-width: 62ch; margin: 0 0 20px; }
.topic-meta { display: flex; flex-wrap: wrap; align-items: center; gap: 10px; font-size: 13.5px; color: var(--ink-3); }
.meta-chip { display: inline-flex; align-items: center; gap: 6px; }
.meta-chip svg { width: 15px; height: 15px; }
.meta-tags { display: flex; gap: 6px; margin-left: 4px; }
.tag { padding: 3px 9px; border-radius: 7px; background: var(--surface-2); border: 1px solid var(--line); font-size: 12px; color: var(--ink-2); }

/* ---------- content actions: copy + print ---------- */
.topic-toolbar { display: flex; gap: 8px; flex-shrink: 0; }
.tool-btn {
  display: inline-flex; align-items: center; gap: 7px;
  padding: 7px 13px; border: 1px solid var(--line); border-radius: 10px;
  background: var(--surface); color: var(--ink-2); cursor: pointer;
  font: 600 13px/1 var(--font-body); transition: color .15s, border-color .15s, background .15s, transform .15s;
}
.tool-btn svg { width: 15px; height: 15px; }
.tool-btn:hover { color: var(--accent); border-color: color-mix(in oklab, var(--accent) 45%, var(--line)); background: var(--accent-soft); transform: translateY(-1px); }
.tool-btn.copied { color: var(--accent); border-color: var(--accent); background: var(--accent-soft); }

/* ---------- interactive animation buttons (theme the .anim-btn) ---------- */
.animation-wrapper .anim-btn {
  background: linear-gradient(135deg, var(--accent), color-mix(in oklab, var(--accent) 68%, #000));
  color: var(--on-accent); border: none; box-shadow: none;
  font-family: var(--font-body); font-weight: 600; border-radius: 10px;
}
.animation-wrapper .anim-btn:hover {
  background: color-mix(in oklab, var(--accent) 88%, #000);
  box-shadow: 0 4px 14px -4px color-mix(in oklab, var(--accent) 50%, transparent);
}

/* ---------- sticky context bar ---------- */
.topic-stickybar {
  position: fixed; top: var(--header-h); left: 0; right: 0; z-index: 90;
  background: color-mix(in oklab, var(--bg) 85%, transparent);
  backdrop-filter: saturate(1.4) blur(12px);
  border-bottom: 1px solid var(--line);
  transform: translateY(-110%); opacity: 0; pointer-events: none;
  transition: transform .25s cubic-bezier(.2,.7,.2,1), opacity .2s;
}
.topic-stickybar.in { transform: translateY(0); opacity: 1; pointer-events: auto; }
.sb-inner { max-width: var(--maxw); margin: 0 auto; padding: 9px 22px; display: flex; align-items: center; gap: 16px; }
.sb-title { display: flex; align-items: center; gap: 9px; font-family: var(--font-display); font-weight: 700; font-size: 15px; letter-spacing: -.01em; color: var(--ink); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.sb-dot { width: 8px; height: 8px; border-radius: 50%; background: var(--accent); flex-shrink: 0; }
.sb-actions { margin-left: auto; display: flex; gap: 8px; flex-shrink: 0; }
.sb-actions .tool-btn { padding: 6px 11px; }

/* ---------- topic grid ---------- */
.topic-grid { display: grid; grid-template-columns: minmax(0, 1fr) 250px; gap: 52px; align-items: start; }
.topic-content { min-width: 0; } /* allow grid track to shrink; children (pre/katex) scroll internally */
.topic-aside { position: sticky; top: calc(var(--header-h) + 22px); }
.toc { border-left: 2px solid var(--line); padding: 2px 0 2px 16px; max-height: calc(100vh - var(--header-h) - 60px); overflow: auto; }
.toc-head { font-size: 12px; text-transform: uppercase; letter-spacing: .12em; color: var(--ink-3); font-weight: 700; margin: 0 0 10px; }
.toc nav ul { list-style: none; margin: 0; padding: 0; }
.toc nav ul ul { padding-left: 14px; }
.toc nav li { margin: 2px 0; }
.toc nav a { display: block; padding: 4px 0; font-size: 13.5px; color: var(--ink-3); line-height: 1.4; transition: color .15s; }
.toc nav a:hover { color: var(--ink); }
.toc nav a.toc-active { color: var(--accent); font-weight: 600; }

/* ============================================================
   PROSE — the reading experience
   ============================================================ */
.prose { font-size: 1.06rem; color: var(--ink); }
.prose > h1 { display: none; } /* title rendered in hero */
.prose h2 {
  font-family: var(--font-display); font-weight: 700; letter-spacing: -.02em;
  font-size: clamp(1.5rem, 3vw, 1.9rem); line-height: 1.2;
  margin: 2.4em 0 .7em; padding-top: .3em;
  scroll-margin-top: calc(var(--header-h) + 16px);
}
.prose h2::before {
  content: ""; display: block; width: 42px; height: 4px; border-radius: 4px;
  background: var(--accent); margin-bottom: 16px;
}
.prose h3 { font-family: var(--font-display); font-weight: 600; font-size: 1.28rem; margin: 1.8em 0 .5em; letter-spacing: -.01em; scroll-margin-top: calc(var(--header-h) + 16px); }
.prose h4 { font-weight: 600; font-size: 1.08rem; margin: 1.4em 0 .4em; color: var(--ink); }
.prose p { margin: 0 0 1.15em; }
.prose a:not(.related-card):not(.pager-link) { color: var(--accent); font-weight: 500; text-decoration: underline; text-decoration-color: color-mix(in oklab, var(--accent) 35%, transparent); text-underline-offset: 3px; }
.prose a:hover { text-decoration-color: var(--accent); }
.prose ul, .prose ol { margin: 0 0 1.2em; padding-left: 1.3em; }
.prose li { margin: .35em 0; }
.prose li::marker { color: var(--accent); }
.prose strong { font-weight: 600; }
.prose hr { border: 0; height: 1px; background: var(--line); margin: 2.6em 0; }

/* tables */
.prose table { width: 100%; border-collapse: collapse; margin: 1.4em 0; font-size: .96rem; border: 1px solid var(--line); border-radius: var(--r); overflow: hidden; }
.prose thead th { background: var(--accent-soft); color: color-mix(in oklab, var(--accent) 78%, var(--ink)); font-weight: 700; text-align: left; }
.prose th, .prose td { padding: 11px 14px; border-bottom: 1px solid var(--line); }
.prose tbody tr:last-child td { border-bottom: 0; }
.prose tbody tr:nth-child(even) { background: var(--surface-2); }

/* code */
.prose code { font-family: var(--font-mono); font-size: .88em; background: var(--surface-2); padding: .15em .42em; border-radius: 6px; border: 1px solid var(--line); }
.prose pre { background: var(--surface-2); border: 1px solid var(--line); border-radius: var(--r); padding: 16px 18px; overflow: auto; margin: 1.4em 0; line-height: 1.5; }
.prose pre code { background: none; border: 0; padding: 0; font-size: .86rem; color: var(--ink-2); }

/* blockquote */
.prose blockquote { margin: 1.4em 0; padding: 4px 18px; border-left: 4px solid var(--accent); background: var(--accent-soft); border-radius: 0 var(--r) var(--r) 0; color: var(--ink-2); }

/* details / summary — practice solutions */
.prose details {
  margin: 1em 0; border: 1px solid var(--line); border-radius: var(--r);
  background: var(--surface); box-shadow: var(--shadow-sm); overflow: hidden;
}
.prose details[open] { box-shadow: var(--shadow-md); }
.prose summary {
  cursor: pointer; list-style: none; padding: 13px 16px; font-weight: 600; color: var(--accent);
  display: flex; align-items: center; gap: 10px; user-select: none;
}
.prose summary::-webkit-details-marker { display: none; }
.prose summary::before {
  content: "+"; display: grid; place-items: center; width: 22px; height: 22px;
  border-radius: 7px; background: var(--accent-soft); color: var(--accent);
  font-weight: 700; font-size: 16px; transition: transform .2s;
}
.prose details[open] summary::before { content: "−"; }
.prose details[open] > summary { border-bottom: 1px solid var(--line); margin-bottom: 8px; }
.prose details > :not(summary) { padding: 0 18px; }
.prose details > :not(summary):last-child { padding-bottom: 16px; }
.prose details p { margin: .5em 0; }
.prose details p:first-of-type { margin-top: 0; }
.prose details ul, .prose details ol { margin: .5em 0; }
/* keep solution math left-aligned and tight (was floating centered with dead space) */
.prose details .katex-display { text-align: left; margin: .7em 0; padding: 0; }
.prose details .katex-display > .katex { font-size: 1.05em; text-align: left; }

/* inline content icons (Lucide) — replace emoji, consistent + themed */
.prose .icon { width: 1.05em; height: 1.05em; vertical-align: -0.16em; }
.icon.ico-bad { color: #ef4444; }
.icon.ico-ok  { color: #16a34a; }
[data-theme="dark"] .icon.ico-bad { color: #f87171; }
[data-theme="dark"] .icon.ico-ok  { color: #34d399; }

/* KaTeX display formulas — give boxed math room and a soft frame */
.prose .katex-display { margin: 1.5em 0; padding: 6px 4px; overflow-x: auto; overflow-y: hidden; }
.prose .katex-display > .katex { font-size: 1.15em; }

/* ---------- pager ---------- */
.pager { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; margin: 3em 0 0; }
.pager-link { display: flex; flex-direction: column; gap: 5px; padding: 16px 18px; border: 1px solid var(--line); border-radius: var(--r); background: var(--surface); box-shadow: var(--shadow-sm); transition: all .18s; }
.pager-link:hover { border-color: var(--accent); transform: translateY(-2px); box-shadow: var(--shadow-md); }
.pager-link.next { text-align: right; }
.pager-dir { font-size: 12.5px; font-weight: 600; color: var(--accent); }
.pager-title { font-weight: 600; color: var(--ink); }

/* ---------- related ---------- */
.related { margin-top: 56px; padding-top: 36px; border-top: 1px solid var(--line); }
.related-head { font-family: var(--font-display); font-weight: 700; font-size: 1.5rem; letter-spacing: -.02em; margin: 0 0 22px; }
.related-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 16px; }
.related-card {
  position: relative; display: flex; flex-direction: column; gap: 7px;
  padding: 20px; border: 1px solid var(--line); border-radius: var(--r-lg);
  background: var(--surface); box-shadow: var(--shadow-sm);
  transition: transform .2s cubic-bezier(.2,.7,.2,1), box-shadow .2s, border-color .2s;
  overflow: hidden;
}
.related-card::after { content: ""; position: absolute; inset: 0 auto 0 0; width: 4px; background: var(--accent); transform: scaleY(0); transform-origin: top; transition: transform .25s; }
.related-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); border-color: color-mix(in oklab, var(--accent) 40%, var(--line)); }
.related-card:hover::after { transform: scaleY(1); }
.rc-kicker { font-size: 11.5px; font-weight: 700; text-transform: uppercase; letter-spacing: .1em; color: var(--accent); }
.rc-title { font-family: var(--font-display); font-weight: 600; font-size: 1.12rem; color: var(--ink); letter-spacing: -.01em; }
.rc-desc { font-size: 13.5px; color: var(--ink-3); line-height: 1.5; }
.rc-go { margin-top: 4px; color: var(--accent); font-weight: 700; transition: transform .2s; }
.related-card:hover .rc-go { transform: translateX(4px); }

/* ---------- newsletter ---------- */
.newsletter { max-width: var(--maxw); margin: 0 auto; padding: 40px 22px 64px; }
.newsletter-card {
  display: flex; flex-wrap: wrap; align-items: center; gap: 32px 48px;
  padding: 34px 38px; border-radius: var(--r-xl);
  background: linear-gradient(135deg, var(--accent-soft), color-mix(in oklab, var(--accent-soft) 50%, var(--surface)));
  border: 1px solid color-mix(in oklab, var(--accent) 22%, var(--line));
}
.newsletter-copy { flex: 1 1 260px; }
.newsletter-copy h2 { font-family: var(--font-display); font-weight: 700; font-size: 1.7rem; letter-spacing: -.02em; margin: 0 0 8px; }
.newsletter-copy p { margin: 0; color: var(--ink-2); max-width: 38ch; }
.newsletter-form { flex: 1.4 1 340px; }
.nl-fields { display: flex; flex-wrap: wrap; gap: 10px; }
.nl-input { flex: 1; min-width: 150px; padding: 12px 14px; border-radius: 11px; border: 1px solid var(--line-2); background: var(--surface); color: var(--ink); font: 400 15px var(--font-body); }
.nl-input:focus { outline: 2px solid var(--accent); outline-offset: 1px; border-color: var(--accent); }
.nl-btn { display: inline-flex; align-items: center; gap: 8px; padding: 12px 20px; border-radius: 11px; border: none; cursor: pointer; background: var(--accent); color: var(--on-accent); font: 600 15px var(--font-body); transition: filter .15s, transform .15s; }
.nl-btn:hover { filter: brightness(1.06); transform: translateY(-1px); }
.nl-btn svg { width: 17px; height: 17px; }
.nl-consent { margin: 12px 0 0; font-size: 12.5px; color: var(--ink-3); }
.nl-consent a { color: var(--accent); text-decoration: underline; }
.nl-visually-hidden { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0 0 0 0); border: 0; }
@media (max-width: 680px) { .newsletter-card { padding: 22px; } .nl-btn { width: 100%; justify-content: center; } }

/* ---------- footer ---------- */
.site-footer { border-top: 1px solid var(--line); background: var(--bg-tint); }
.footer-inner { max-width: var(--maxw); margin: 0 auto; padding: 48px 22px 28px; display: flex; flex-wrap: wrap; gap: 40px; justify-content: space-between; }
.footer-brand .brand-text { font-family: var(--font-display); font-size: 22px; font-weight: 700; }
.footer-brand em { color: var(--accent); font-style: normal; }
.footer-brand p { color: var(--ink-3); max-width: 30ch; margin: 10px 0 0; font-size: 14px; }
.footer-cols { display: flex; gap: 54px; }
.footer-col h4 { font-size: 12px; text-transform: uppercase; letter-spacing: .12em; color: var(--ink-3); margin: 0 0 12px; }
.footer-col a { display: block; padding: 4px 0; color: var(--ink-2); font-size: 14.5px; }
.footer-col a:hover { color: var(--accent); }
.footer-base { max-width: var(--maxw); margin: 0 auto; padding: 18px 22px 28px; border-top: 1px solid var(--line); display: flex; justify-content: space-between; font-size: 13px; color: var(--ink-3); }

/* ---------- mobile bottom nav ---------- */
.bottom-nav { display: none; }

/* ---------- motion ---------- */
@keyframes rise { from { opacity: 0; transform: translateY(16px); } to { opacity: 1; transform: translateY(0); } }
.reveal { animation: rise .6s cubic-bezier(.2,.7,.2,1) both; }
.related-card { opacity: 0; }
.related-card.in { animation: rise .55s cubic-bezier(.2,.7,.2,1) both; }

@media (prefers-reduced-motion: reduce) {
  * { animation: none !important; transition: none !important; scroll-behavior: auto; }
  .reveal, .related-card { opacity: 1; }
}

/* ---------- responsive ---------- */
@media (max-width: 920px) {
  .topic-grid { grid-template-columns: minmax(0, 1fr); gap: 0; }
  .topic-aside { display: none; }
}
@media (max-width: 680px) {
  .primary-nav { display: none; }
  .site-main { padding-bottom: 96px; }
  .pager { grid-template-columns: 1fr; }
  .footer-inner { flex-direction: column; gap: 28px; }
  .footer-cols { gap: 40px; }

  .bottom-nav {
    display: flex; position: fixed; bottom: 0; left: 0; right: 0; z-index: 110;
    background: color-mix(in oklab, var(--bg) 88%, transparent);
    backdrop-filter: saturate(1.4) blur(14px);
    border-top: 1px solid var(--line); padding: 8px 6px calc(8px + env(safe-area-inset-bottom));
    justify-content: space-around;
  }
  .bn-item { display: flex; flex-direction: column; align-items: center; gap: 3px; padding: 4px 10px; color: var(--ink-3); font-size: 11px; font-weight: 600; border-radius: 12px; }
  .bn-item svg { width: 22px; height: 22px; }
  .bn-item.is-active { color: var(--accent); }
  .bn-physics.is-active { color: var(--phy); }
  .bn-chemistry.is-active { color: var(--chem); }
  .bn-mathematics.is-active { color: var(--math); }
}

@media (max-width: 480px) {
  .tool-btn .tb-label { display: none; }
  .tool-btn { padding: 8px; }
  .sb-title { font-size: 14px; }
}

/* ---------- listing (subject + chapter list pages) ---------- */
.listing { padding-bottom: 20px; }
.listing-hero { padding: 18px 0 26px; border-bottom: 1px solid var(--line); margin-bottom: 30px; }
.listing-title { font-family: var(--font-display); font-weight: 800; letter-spacing: -.03em; font-size: clamp(2rem, 5vw, 3rem); margin: 14px 0 12px; }
.listing-lede { font-size: 1.1rem; color: var(--ink-2); max-width: 60ch; margin: 0; }
.chapter-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 18px; }
.chapter-card { display: flex; flex-direction: column; gap: 8px; padding: 22px; border: 1px solid var(--line); border-radius: var(--r-lg); background: var(--surface); box-shadow: var(--shadow-sm); transition: transform .2s, box-shadow .2s, border-color .2s; }
.chapter-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); border-color: color-mix(in oklab, var(--accent) 40%, var(--line)); }
.cc-title { font-family: var(--font-display); font-weight: 600; font-size: 1.18rem; color: var(--ink); }
.cc-desc { font-size: 14px; color: var(--ink-3); line-height: 1.5; flex: 1; }
.cc-meta { display: flex; align-items: center; justify-content: space-between; font-size: 12.5px; color: var(--accent); font-weight: 600; }

/* ---------- print / save-as-PDF ---------- */
@media print {
  .site-header, .topic-stickybar, .bottom-nav, .site-footer, .reading-progress,
  .topic-aside, .topic-toolbar, .related, .pager, .skip-link, .crumbs, .newsletter { display: none !important; }
  body, body::before { background: #fff !important; }
  body::before { display: none; }
  /* JEENotes.in watermark — fixed, so it repeats on every printed page */
  body::after {
    content: "JEENotes.in";
    position: fixed; top: 50%; left: 50%;
    transform: translate(-50%, -50%) rotate(-30deg);
    font-family: "Bricolage Grotesque", sans-serif;
    font-size: 4.5rem; font-weight: 800; letter-spacing: .04em;
    color: rgba(0, 0, 0, 0.08); white-space: nowrap;
    z-index: 9999; pointer-events: none;
  }
  .site-main { max-width: none; padding: 0; }
  .topic-grid { display: block; }
  body, .prose, .topic-lede, .meta-chip { color: #000 !important; }
  .topic-title { -webkit-text-fill-color: #000 !important; color: #000 !important; background: none !important; }
  .prose h2::before { background: #000 !important; }
  a { color: #000 !important; text-decoration: underline; }
  /* expand all collapsibles so answers print */
  details > :not(summary) { display: block !important; }
  details { border: 1px solid #ccc !important; box-shadow: none !important; }
}

/* ============================================================
   HOME PAGE
   ============================================================ */

/* ── Hero ────────────────────────────────────────────────────── */
.home-hero {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
  align-items: center;
  padding: 72px 0 80px;
}

.home-hero__kicker {
  display: inline-flex; align-items: center; gap: 8px;
  font-size: 13px; font-weight: 600; letter-spacing: .06em;
  text-transform: uppercase; color: var(--accent);
  margin: 0 0 20px;
}

.home-hero__title {
  font-family: var(--font-display);
  font-weight: 800;
  letter-spacing: -.04em;
  font-size: clamp(2.6rem, 6vw, 4rem);
  line-height: 1.03;
  margin: 0 0 22px;
  color: var(--ink);
}

.home-hero__accent {
  background: linear-gradient(130deg, var(--accent), color-mix(in oklab, var(--accent) 60%, #a78bfa));
  -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent;
}

.home-hero__lede {
  font-size: clamp(1.05rem, 2vw, 1.2rem);
  color: var(--ink-2);
  max-width: 50ch;
  margin: 0 0 36px;
  line-height: 1.65;
}

.home-hero__actions { display: flex; gap: 14px; flex-wrap: wrap; }

.home-btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 13px 24px; border-radius: var(--r-lg); font-weight: 600;
  font-size: 15px; font-family: var(--font-body);
  transition: transform .18s, box-shadow .18s, filter .18s;
}
.home-btn:hover { transform: translateY(-2px); }

.home-btn--primary {
  background: var(--accent); color: var(--on-accent);
  box-shadow: 0 4px 18px -4px color-mix(in oklab, var(--accent) 55%, transparent);
}
.home-btn--primary:hover {
  filter: brightness(1.07);
  box-shadow: 0 8px 26px -6px color-mix(in oklab, var(--accent) 60%, transparent);
}

.home-btn--ghost {
  background: var(--surface); color: var(--ink-2);
  border: 1px solid var(--line); box-shadow: var(--shadow-sm);
}
.home-btn--ghost:hover { color: var(--ink); border-color: var(--line-2); box-shadow: var(--shadow-md); }

/* decorative orb cluster */
.home-hero__visual {
  position: relative; height: 340px;
  display: flex; align-items: center; justify-content: center;
}
.home-hero__orb {
  position: absolute; border-radius: 50%; filter: blur(2px);
}
.home-hero__orb--a {
  width: 220px; height: 220px;
  background: radial-gradient(circle at 38% 38%, color-mix(in oklab, var(--phy) 45%, transparent), transparent 70%);
}
.home-hero__orb--b {
  width: 180px; height: 180px; top: 30px; right: 20px;
  background: radial-gradient(circle at 62% 38%, color-mix(in oklab, var(--chem) 40%, transparent), transparent 70%);
}
.home-hero__orb--c {
  width: 150px; height: 150px; bottom: 30px; left: 20px;
  background: radial-gradient(circle at 50% 60%, color-mix(in oklab, var(--math) 38%, transparent), transparent 70%);
}

/* ── Section wrapper ─────────────────────────────────────────── */
.home-section { padding: 56px 0 0; }
.home-section__heading {
  font-family: var(--font-display);
  font-weight: 700; font-size: clamp(1.5rem, 3vw, 2rem);
  letter-spacing: -.025em; color: var(--ink);
  margin: 0 0 28px;
}

/* ── Subject cards ───────────────────────────────────────────── */
.subjects-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.home-card {
  display: flex; flex-direction: column; gap: 10px;
  padding: 26px; border-radius: var(--r-lg);
  border: 1px solid var(--line);
  background: var(--surface);
  box-shadow: var(--shadow-sm);
  transition: transform .2s cubic-bezier(.2,.7,.2,1), box-shadow .2s, border-color .2s;
  text-decoration: none; color: inherit;
}
.home-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-lg);
  border-color: color-mix(in oklab, var(--accent) 40%, var(--line));
}

.home-card--subject .home-card__icon {
  display: flex; align-items: center; justify-content: center;
  width: 56px; height: 56px; border-radius: var(--r);
  background: var(--accent-soft);
  color: var(--accent);
  margin-bottom: 4px;
  transition: background .2s;
}
.home-card--subject:hover .home-card__icon { background: color-mix(in oklab, var(--accent-soft) 70%, var(--accent)); }

.home-card__subject-label {
  font-family: var(--font-display);
  font-weight: 700; font-size: 1.25rem;
  letter-spacing: -.02em; color: var(--ink);
}

.home-card__kicker {
  font-size: 11.5px; font-weight: 700;
  text-transform: uppercase; letter-spacing: .1em;
  color: var(--accent);
}

.home-card__title {
  font-family: var(--font-display);
  font-weight: 600; font-size: 1.1rem;
  color: var(--ink); letter-spacing: -.01em;
}

.home-card__desc {
  font-size: 14px; color: var(--ink-3); line-height: 1.55; flex: 1;
}

.home-card__go {
  font-weight: 700; color: var(--accent);
  transition: transform .2s; display: block;
}
.home-card:hover .home-card__go { transform: translateX(4px); }

/* ── Recent topics ───────────────────────────────────────────── */
.recent-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(270px, 1fr));
  gap: 18px;
}

.home-card--recent {
  position: relative; overflow: hidden;
}
.home-card--recent::before {
  content: ""; position: absolute; inset: 0 auto 0 0;
  width: 4px; background: var(--accent);
  transform: scaleY(0); transform-origin: top;
  transition: transform .25s cubic-bezier(.2,.7,.2,1);
}
.home-card--recent:hover::before { transform: scaleY(1); }

/* ── Features / Why section ──────────────────────────────────── */
.home-features { padding-bottom: 24px; }

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 20px;
}

.feature-tile {
  padding: 26px 24px; border-radius: var(--r-lg);
  background: var(--surface-2);
  border: 1px solid var(--line);
}

.feature-tile__icon {
  display: flex; align-items: center; justify-content: center;
  width: 50px; height: 50px; border-radius: var(--r);
  background: var(--accent-soft);
  color: var(--accent);
  margin-bottom: 16px;
}

.feature-tile__title {
  font-family: var(--font-display);
  font-weight: 600; font-size: 1.1rem;
  letter-spacing: -.01em; margin: 0 0 8px; color: var(--ink);
}

.feature-tile__body {
  font-size: 14px; color: var(--ink-3); line-height: 1.6; margin: 0;
}

/* ── Responsive ──────────────────────────────────────────────── */
@media (max-width: 860px) {
  .home-hero { grid-template-columns: 1fr; gap: 32px; padding: 48px 0 56px; }
  .home-hero__visual { display: none; }
  .subjects-grid { grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); }
}

@media (max-width: 680px) {
  .home-hero { padding: 32px 0 40px; }
  .home-hero__title { font-size: clamp(2.1rem, 8vw, 2.8rem); }
  .subjects-grid { grid-template-columns: 1fr; }
  .home-section { padding-top: 40px; }
}

@media print {
  .home-hero__visual, .home-hero__orb { display: none; }
}

/* ============================================================
   SEARCH PAGE
   ============================================================ */

/* search.js uses --accent-physics/chemistry/math; map to v2 tokens */
:root {
  --accent-physics:   var(--phy);
  --accent-chemistry: var(--chem);
  --accent-math:      var(--math);
  --accent-primary:   var(--brand);
}

.search-page { padding-bottom: 60px; }

.search-hero { padding: 32px 0 28px; border-bottom: 1px solid var(--line); margin-bottom: 32px; }
.search-hero__title {
  font-family: var(--font-display); font-weight: 800; letter-spacing: -.03em;
  font-size: clamp(2rem, 5vw, 3rem); margin: 0 0 10px;
}
.search-hero__lede { font-size: 1.1rem; color: var(--ink-2); margin: 0; }

/* shared input wrapper (used on search page + 404) */
.search-box-wrap { display: flex; flex-direction: column; gap: 14px; margin-bottom: 20px; }
.search-input-wrap {
  position: relative; display: flex; align-items: center;
}
.search-icon {
  position: absolute; left: 14px; width: 18px; height: 18px;
  color: var(--ink-3); pointer-events: none; flex-shrink: 0;
}
.search-input {
  width: 100%; padding: 13px 44px 13px 44px;
  border: 1px solid var(--line-2); border-radius: var(--r-lg);
  background: var(--surface); color: var(--ink);
  font: 400 16px/1.4 var(--font-body);
  box-shadow: var(--shadow-sm);
  transition: border-color .15s, box-shadow .15s;
  -webkit-appearance: none; appearance: none;
}
.search-input::placeholder { color: var(--ink-3); }
.search-input:focus {
  outline: none; border-color: var(--accent);
  box-shadow: 0 0 0 3px color-mix(in oklab, var(--accent) 18%, transparent), var(--shadow-sm);
}
/* hide browser's native clear button so ours is the only one */
.search-input::-webkit-search-cancel-button { -webkit-appearance: none; }
.search-clear {
  position: absolute; right: 12px;
  display: flex; align-items: center; justify-content: center;
  width: 28px; height: 28px; border-radius: 8px;
  border: none; background: var(--surface-2); color: var(--ink-3);
  cursor: pointer; transition: background .15s, color .15s;
}
.search-clear:hover { background: var(--line); color: var(--ink); }
.search-clear svg { width: 14px; height: 14px; }

/* filter pills */
.search-filters { display: flex; flex-wrap: wrap; gap: 8px; }
.filter-btn {
  padding: 7px 16px; border-radius: 999px;
  border: 1px solid var(--line); background: var(--surface);
  color: var(--ink-2); font: 600 13.5px var(--font-body);
  cursor: pointer; transition: color .15s, background .15s, border-color .15s;
}
.filter-btn:hover { color: var(--ink); border-color: var(--line-2); }
.filter-btn.active {
  color: var(--accent); background: var(--accent-soft);
  border-color: color-mix(in oklab, var(--accent) 30%, transparent);
}

/* status line */
.search-info { font-size: 14px; color: var(--ink-3); margin: 0 0 20px; min-height: 1.4em; }

/* results grid */
.search-results { display: flex; flex-direction: column; gap: 12px; }

/* each result item (injected by search.js as <a class="search-result-item">) */
.search-result-item {
  display: flex; flex-direction: column; gap: 8px;
  padding: 20px 22px; border: 1px solid var(--line); border-radius: var(--r-lg);
  background: var(--surface); box-shadow: var(--shadow-sm);
  transition: transform .18s cubic-bezier(.2,.7,.2,1), box-shadow .18s, border-color .18s;
  position: relative; overflow: hidden;
}
.search-result-item::before {
  content: ""; position: absolute; inset: 0 auto 0 0; width: 4px;
  background: var(--subject-color, var(--accent));
  transform: scaleY(0); transform-origin: top; transition: transform .22s;
}
.search-result-item:hover {
  transform: translateY(-3px); box-shadow: var(--shadow-md);
  border-color: color-mix(in oklab, var(--accent) 35%, var(--line));
}
.search-result-item:hover::before { transform: scaleY(1); }

.result-header { display: flex; align-items: baseline; gap: 10px; flex-wrap: wrap; }
.result-subject {
  font-size: 11.5px; font-weight: 700; text-transform: uppercase;
  letter-spacing: .09em; color: var(--subject-color, var(--accent));
  flex-shrink: 0;
}
.result-title {
  font-family: var(--font-display); font-weight: 600; font-size: 1.1rem;
  color: var(--ink); margin: 0; letter-spacing: -.01em;
}
.result-title mark {
  background: color-mix(in oklab, var(--accent) 22%, transparent);
  color: var(--accent); border-radius: 3px; padding: 0 2px;
}
.result-snippet { font-size: 14px; color: var(--ink-2); line-height: 1.55; margin: 0; }
.result-tags { display: flex; flex-wrap: wrap; gap: 6px; }
.result-tag {
  font-size: 12px; padding: 2px 9px; border-radius: 7px;
  background: var(--surface-2); border: 1px solid var(--line); color: var(--ink-3);
}

/* no-results message */
.no-results { padding: 32px 0; color: var(--ink-3); }
.no-results p { margin: 0 0 6px; }

/* ============================================================
   404 PAGE
   ============================================================ */
.error-page {
  max-width: 620px; margin: 0 auto;
  padding: 64px 0 80px; text-align: center;
  display: flex; flex-direction: column; align-items: center; gap: 28px;
}
.error-badge {
  font-family: var(--font-display); font-weight: 800;
  font-size: clamp(5rem, 20vw, 9rem); letter-spacing: -.06em; line-height: 1;
  background: linear-gradient(160deg, var(--accent), color-mix(in oklab, var(--accent) 50%, var(--line)));
  -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent;
  user-select: none;
}
.error-title {
  font-family: var(--font-display); font-weight: 700; font-size: 2rem;
  letter-spacing: -.03em; margin: 0;
}
.error-lede { font-size: 1.05rem; color: var(--ink-2); max-width: 44ch; margin: 0; line-height: 1.65; }

/* inline search on 404 */
.error-search { width: 100%; display: flex; flex-direction: column; align-items: center; gap: 10px; }
.error-search .search-input-wrap { width: 100%; }
.error-search-link {
  display: inline-flex; align-items: center; gap: 6px;
  font-size: 14px; font-weight: 600; color: var(--accent);
  text-decoration: underline; text-decoration-color: color-mix(in oklab, var(--accent) 35%, transparent);
  text-underline-offset: 3px; transition: text-decoration-color .15s;
}
.error-search-link:hover { text-decoration-color: var(--accent); }
.error-search-link svg { width: 14px; height: 14px; }

/* subject shortcuts */
.error-subjects {
  display: flex; gap: 12px; flex-wrap: wrap; justify-content: center; width: 100%;
}
.error-subject-card {
  display: flex; align-items: center; gap: 10px;
  padding: 14px 20px; border-radius: var(--r-lg);
  border: 1px solid var(--line); background: var(--surface);
  box-shadow: var(--shadow-sm); flex: 1 1 140px; max-width: 200px;
  transition: transform .18s, box-shadow .18s, border-color .18s;
}
.error-subject-card:hover { transform: translateY(-3px); box-shadow: var(--shadow-md); }
.esc-dot { width: 10px; height: 10px; border-radius: 50%; flex-shrink: 0; }
.esc-label { font-weight: 600; font-size: 15px; color: var(--ink); flex: 1; }
.esc-arrow { width: 16px; height: 16px; color: var(--ink-3); flex-shrink: 0; transition: transform .18s; }
.error-subject-card:hover .esc-arrow { transform: translateX(3px); color: var(--ink); }

.error-home {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 11px 22px; border-radius: 999px;
  border: 1px solid var(--line); background: var(--surface);
  color: var(--ink-2); font: 600 14.5px var(--font-body);
  box-shadow: var(--shadow-sm); transition: color .15s, border-color .15s, transform .15s;
}
.error-home:hover { color: var(--accent); border-color: color-mix(in oklab, var(--accent) 40%, var(--line)); transform: translateY(-2px); }
.error-home svg { width: 17px; height: 17px; }

@media (max-width: 480px) {
  .error-page { padding: 40px 0 60px; gap: 22px; }
  .error-subjects { flex-direction: column; align-items: stretch; }
  .error-subject-card { max-width: none; }
}

/* ============================================================
   PYQ — Previous Year Question cards
   ============================================================ */

/* Page-level badge in the hero eyebrow */
.pyq-page-badge {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 4px 12px; border-radius: 999px; font-size: 12.5px; font-weight: 600;
  color: var(--brand); background: var(--brand-soft);
  border: 1px solid color-mix(in oklab, var(--brand) 22%, transparent);
}
.pyq-page-badge svg { width: 14px; height: 14px; }

/* Question card wrapper */
.pyq-question {
  margin: 2em 0;
  border: 1px solid var(--line);
  border-radius: var(--r-lg);
  background: var(--surface);
  box-shadow: var(--shadow-sm);
  overflow: hidden;
  transition: box-shadow .2s;
}
.pyq-question:hover { box-shadow: var(--shadow-md); }

/* Badge row at the top of each card */
.pyq-badge-row {
  display: flex; align-items: center; gap: 10px; flex-wrap: wrap;
  padding: 12px 18px;
  background: var(--surface-2);
  border-bottom: 1px solid var(--line);
}
.pyq-badge {
  display: inline-flex; align-items: center; gap: 6px;
  font-size: 12px; font-weight: 700; letter-spacing: .04em; text-transform: uppercase;
  color: var(--accent);
}
.pyq-icon { width: 14px; height: 14px; }
.pyq-year-shift {
  font-size: 13px; color: var(--ink-2); font-weight: 500;
}
.pyq-qid {
  margin-left: auto; font-size: 11.5px; color: var(--ink-3);
  font-family: var(--font-mono); letter-spacing: .02em;
}

/* Question statement — sits inside .prose so existing prose rules apply */
.pyq-statement {
  padding: 18px 20px 6px;
}
/* Options rendered as an ordered list inside the statement */
.pyq-statement ol.pyq-options {
  list-style: none; padding: 0; margin: 16px 0 0;
  display: grid; gap: 8px;
}
.pyq-statement ol.pyq-options li {
  display: flex; align-items: flex-start; gap: 10px;
  padding: 10px 14px; border-radius: var(--r);
  border: 1px solid var(--line); background: var(--bg);
  font-size: .97rem; line-height: 1.55; transition: border-color .15s, background .15s;
}
.pyq-statement ol.pyq-options li:hover {
  border-color: color-mix(in oklab, var(--accent) 40%, var(--line));
  background: var(--accent-soft);
}
.pyq-option-label {
  flex-shrink: 0; width: 22px; height: 22px;
  display: grid; place-items: center; border-radius: 6px;
  background: var(--surface-2); border: 1px solid var(--line);
  font-size: 12px; font-weight: 700; color: var(--ink-2);
}

/* Answer reveal row */
.pyq-answer-row {
  padding: 10px 20px 6px;
  display: flex; align-items: center; gap: 12px;
}
.pyq-reveal-btn {
  display: inline-flex; align-items: center; gap: 7px;
  padding: 6px 14px; border: 1px solid var(--line); border-radius: 8px;
  background: var(--surface); color: var(--ink-2);
  font: 600 13px var(--font-body); cursor: pointer;
  transition: color .15s, border-color .15s, background .15s;
}
.pyq-reveal-btn svg { width: 15px; height: 15px; }
.pyq-reveal-btn:hover {
  color: var(--accent);
  border-color: color-mix(in oklab, var(--accent) 45%, var(--line));
  background: var(--accent-soft);
}
.pyq-answer-chip {
  display: inline-flex; align-items: center; gap: 7px;
  padding: 5px 14px; border-radius: 8px; font-weight: 700; font-size: 14px;
  color: #16a34a; background: #f0fdf4; border: 1px solid #bbf7d0;
}
[data-theme="dark"] .pyq-answer-chip {
  color: #34d399; background: color-mix(in oklab, #34d399 12%, transparent); border-color: color-mix(in oklab, #34d399 30%, transparent);
}
.pyq-answer-chip svg { width: 15px; height: 15px; }

/* Solution collapsible lives inside .pyq-statement which is inside .prose,
   so existing .prose details / .prose summary rules already apply.
   We just need the gap below the card. */
.pyq-statement .solution {
  margin-top: 16px;
}

/* Attribution footer */
.pyq-attribution {
  display: flex; align-items: center; gap: 7px;
  padding: 10px 20px 14px;
  font-size: 12.5px; color: var(--ink-3); font-weight: 500;
  border-top: 1px solid var(--line); margin-top: 10px;
}
.pyq-attr-icon { width: 14px; height: 14px; flex-shrink: 0; }

/* Print: always expand solutions, simplify cards */
@media print {
  .pyq-question { box-shadow: none; border: 1px solid #ccc; break-inside: avoid; }
  .pyq-reveal-btn { display: none; }
  .pyq-answer-chip { display: inline-flex !important; }
  .pyq-statement details { border: 1px solid #ddd; }
  .pyq-statement details > :not(summary) { display: block !important; }
}

/* Narrow screens */
@media (max-width: 600px) {
  .pyq-badge-row { padding: 10px 14px; }
  .pyq-statement { padding: 14px 14px 4px; }
  .pyq-answer-row { padding: 8px 14px 4px; }
  .pyq-attribution { padding: 8px 14px 12px; }
}