/* ═══════════════════════════════════════════════════════
   notes.css — Shared stylesheet for StudyHub subject notes
   Extracted from STQA notes · Reusable across all subjects
   ═══════════════════════════════════════════════════════ */

/* ── GOOGLE FONTS ── */
@import url('https://fonts.googleapis.com/css2?family=Playfair+Display:wght@700;900&family=Source+Sans+3:wght@300;400;600&family=JetBrains+Mono:wght@400;700&display=swap');

/* ── CSS VARIABLES ── */
:root {
  --bg: #0d0f14;
  --surface: #13161e;
  --card: #1a1e2a;
  --border: #252a3a;
  --accent: #e8a045;
  --accent2: #4fc3f7;
  --accent3: #81c784;
  --accent4: #ce93d8;
  --text: #e2e8f0;
  --muted: #8892a4;
  --danger: #ef5350;
  --unit1: #e8a045;
  --unit2: #4fc3f7;
  --unit3: #81c784;
  --unit4: #ce93d8;
  --unit5: #f06292;
}

/* ── RESET ── */
* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }

/* ── BASE ── */
body {
  background: var(--bg);
  color: var(--text);
  font-family: 'Source Sans 3', sans-serif;
  font-size: 16px;
  line-height: 1.7;
}

/* ══════════════════════════════
   NAVBAR (from sqta.html)
   ══════════════════════════════ */
.navbar {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  background: rgba(13, 15, 20, 0.97);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--border);
  height: 58px;
}
.navbar .container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px;
  height: 100%;
}
.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
  gap: 16px;
}
.nav-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--text);
  text-decoration: none;
  font-weight: 700;
  font-size: 17px;
  letter-spacing: -0.3px;
  white-space: nowrap;
}
.logo-icon {
  font-size: 20px;
  line-height: 1;
}
.nav-links {
  display: flex;
  align-items: center;
  gap: 6px;
  overflow-x: auto;
  white-space: nowrap;
}
.nav-links a {
  color: var(--muted);
  text-decoration: none;
  font-size: 13px;
  font-weight: 600;
  padding: 6px 14px;
  border-radius: 20px;
  transition: all 0.2s;
  letter-spacing: 0.3px;
}
.nav-links a:hover,
.nav-links a.active {
  color: var(--text);
  background: var(--card);
}
.nav-insta {
  display: flex;
  align-items: center;
  gap: 6px;
  color: var(--accent) !important;
  border: 1px solid rgba(232,160,69,0.25) !important;
  background: rgba(232,160,69,0.07) !important;
}
.nav-insta:hover {
  background: rgba(232,160,69,0.15) !important;
}

/* Unit nav links (STQA quick-nav kept as supplemental) */
nav.unit-nav {
  position: fixed;
  top: 58px;
  left: 0; right: 0;
  z-index: 99;
  background: rgba(13,15,20,0.95);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  padding: 0 24px;
  display: flex;
  align-items: center;
  gap: 8px;
  height: 46px;
  overflow-x: auto;
  white-space: nowrap;
}
nav.unit-nav a {
  color: var(--muted);
  text-decoration: none;
  font-size: 12px;
  font-weight: 600;
  padding: 5px 13px;
  border-radius: 20px;
  transition: all 0.2s;
  letter-spacing: 0.4px;
  text-transform: uppercase;
  flex-shrink: 0;
}
nav.unit-nav a:hover { color: var(--text); background: var(--card); }
nav.unit-nav a.u1 { color: var(--unit1); }
nav.unit-nav a.u2 { color: var(--unit2); }
nav.unit-nav a.u3 { color: var(--unit3); }
nav.unit-nav a.u4 { color: var(--unit4); }
nav.unit-nav a.u5 { color: var(--unit5); }

/* ══════════════════════════════
   HERO
   ══════════════════════════════ */
.hero {
  margin-top: 104px; /* navbar 58px + unit-nav 46px */
  padding: 70px 24px 50px;
  text-align: center;
  background: linear-gradient(135deg, #0d0f14 0%, #111520 50%, #0d0f14 100%);
  border-bottom: 1px solid var(--border);
  position: relative;
  overflow: hidden;
}
.hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background: radial-gradient(ellipse 60% 40% at 50% 0%, rgba(232,160,69,.12), transparent);
}
.hero h1 {
  font-family: 'Playfair Display', serif;
  font-size: clamp(32px, 6vw, 58px);
  font-weight: 900;
  letter-spacing: -1px;
  position: relative;
  background: linear-gradient(135deg, #e8a045, #f4c17a);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero p {
  color: var(--muted);
  max-width: 600px;
  margin: 14px auto 0;
  font-size: 15px;
  position: relative;
}
.badge-row {
  display: flex;
  gap: 10px;
  justify-content: center;
  margin-top: 20px;
  flex-wrap: wrap;
  position: relative;
}
.badge {
  padding: 4px 14px;
  border-radius: 20px;
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.5px;
  text-transform: uppercase;
}
.badge-gold {
  background: rgba(232,160,69,.15);
  color: var(--accent);
  border: 1px solid rgba(232,160,69,.3);
}
.badge-blue {
  background: rgba(79,195,247,.1);
  color: var(--accent2);
  border: 1px solid rgba(79,195,247,.25);
}

/* ══════════════════════════════
   LAYOUT
   ══════════════════════════════ */
.container {
  max-width: 900px;
  margin: 0 auto;
  padding: 0 20px 80px;
}

/* ══════════════════════════════
   PROJECT BANNER
   ══════════════════════════════ */
.project-banner {
  margin: 40px 0 10px;
  background: linear-gradient(135deg, #1a1e2a, #1e2335);
  border: 1px solid var(--accent);
  border-radius: 16px;
  padding: 28px 30px;
}
.project-banner .label {
  font-size: 11px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: var(--accent);
  margin-bottom: 6px;
}
.project-banner h2 {
  font-family: 'Playfair Display', serif;
  font-size: 24px;
  color: #fff;
  margin-bottom: 8px;
}
.project-banner p {
  color: var(--muted);
  font-size: 14px;
}

/* ══════════════════════════════
   UNIT HEADER
   ══════════════════════════════ */
.unit-header {
  margin: 50px 0 28px;
  padding: 24px 28px;
  border-radius: 14px;
  border-left: 5px solid var(--uc);
  background: linear-gradient(135deg, color-mix(in srgb, var(--uc) 8%, var(--surface)), var(--surface));
}
.unit-header .unit-tag {
  font-size: 11px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1.5px;
  color: var(--uc);
  margin-bottom: 6px;
}
.unit-header h2 {
  font-family: 'Playfair Display', serif;
  font-size: 28px;
  color: #fff;
}
.unit-header .meta {
  color: var(--muted);
  font-size: 13px;
  margin-top: 6px;
}

/* ══════════════════════════════
   TOPIC CARD
   ══════════════════════════════ */
.topic {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  margin-bottom: 20px;
  overflow: hidden;
}
.topic-head {
  padding: 16px 22px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  transition: background 0.2s;
}
.topic-head:hover { background: rgba(255,255,255,.03); }
.topic-head h3 { font-size: 16px; font-weight: 600; color: var(--text); }
.topic-head .arrow { color: var(--muted); font-size: 18px; transition: transform 0.3s; }
.topic-head.open .arrow { transform: rotate(180deg); }
.topic-body {
  padding: 0 22px;
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.4s ease, padding 0.3s;
}
.topic-body.open {
  max-height: 3000px;
  padding: 0 22px 22px;
}

/* ══════════════════════════════
   SECTION BLOCKS
   ══════════════════════════════ */
.sect { margin: 16px 0; }
.sect-label {
  display: inline-block;
  font-size: 10px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1px;
  padding: 3px 10px;
  border-radius: 20px;
  margin-bottom: 10px;
}
.sl-what  { background: rgba(232,160,69,.15); color: var(--accent); }
.sl-how   { background: rgba(79,195,247,.12); color: var(--accent2); }
.sl-eg    { background: rgba(129,199,132,.12); color: var(--accent3); }
.sect p { color: #c5cfe0; font-size: 15px; margin-bottom: 8px; }

/* ══════════════════════════════
   CODE BLOCK
   ══════════════════════════════ */
.code-block {
  background: #0a0c12;
  border: 1px solid #1e2436;
  border-radius: 8px;
  padding: 16px 18px;
  margin: 10px 0;
  font-family: 'JetBrains Mono', monospace;
  font-size: 13px;
  color: #a8c4e0;
  line-height: 1.6;
  overflow-x: auto;
  white-space: pre-wrap;
}
.code-block .cm  { color: #4e6478; }
.code-block .kw  { color: #ce93d8; }
.code-block .str { color: #81c784; }
.code-block .num { color: #f48fb1; }

/* ══════════════════════════════
   PROJECT REF
   ══════════════════════════════ */
.proj-ref {
  background: linear-gradient(135deg, rgba(232,160,69,.06), rgba(232,160,69,.02));
  border: 1px solid rgba(232,160,69,.2);
  border-radius: 10px;
  padding: 14px 18px;
  margin: 14px 0;
  font-size: 14px;
}
.proj-ref strong {
  color: var(--accent);
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.8px;
  display: block;
  margin-bottom: 4px;
}

/* ══════════════════════════════
   COMPARISON TABLE
   ══════════════════════════════ */
.comp-section { margin-top: 30px; }
.comp-section h4 {
  font-family: 'Playfair Display', serif;
  font-size: 18px;
  color: #fff;
  margin-bottom: 14px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border);
}
.comp-table { width: 100%; border-collapse: collapse; font-size: 14px; }
.comp-table th {
  background: var(--card);
  color: var(--accent);
  padding: 10px 14px;
  text-align: left;
  font-weight: 700;
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.6px;
  border-bottom: 2px solid var(--border);
}
.comp-table td {
  padding: 10px 14px;
  border-bottom: 1px solid var(--border);
  color: #c5cfe0;
  vertical-align: top;
}
.comp-table tr:last-child td { border-bottom: none; }
.comp-table tr:hover td { background: rgba(255,255,255,.02); }
.comp-table td:first-child { color: var(--text); font-weight: 600; }

/* ══════════════════════════════
   QUESTION PAPER SECTION
   ══════════════════════════════ */
.qp-section { margin-top: 60px; }
.qp-header {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 28px;
  text-align: center;
  margin-bottom: 24px;
}
.qp-header h2 {
  font-family: 'Playfair Display', serif;
  font-size: 26px;
  color: #fff;
}
.qp-meta {
  display: flex;
  justify-content: space-between;
  margin-top: 14px;
  font-size: 13px;
  color: var(--muted);
  flex-wrap: wrap;
  gap: 8px;
}
.qp-inst {
  margin-top: 14px;
  text-align: left;
  font-size: 13px;
  color: #c5cfe0;
  background: rgba(255,255,255,.03);
  border-radius: 8px;
  padding: 12px 16px;
}
.qp-inst li { margin-left: 20px; margin-bottom: 4px; }

/* Q Blocks */
.q-block {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  margin-bottom: 20px;
  overflow: hidden;
}
.q-title {
  background: rgba(232,160,69,.1);
  padding: 12px 22px;
  font-weight: 700;
  color: var(--accent);
  font-size: 14px;
  letter-spacing: 0.3px;
  border-bottom: 1px solid var(--border);
}
.q-body { padding: 20px 22px; }
.q-item { margin-bottom: 22px; }
.q-item:last-child { margin-bottom: 0; }
.q-stem { font-weight: 600; color: #e2e8f0; margin-bottom: 10px; font-size: 15px; }
.q-marks { float: right; color: var(--accent); font-weight: 700; font-size: 13px; }
.q-ans { color: #b0bec5; font-size: 14px; line-height: 1.75; }
.q-ans p { margin-bottom: 8px; }
.q-ans ul, .q-ans ol { margin-left: 20px; margin-bottom: 8px; }
.q-ans li { margin-bottom: 4px; }
.q-ans strong { color: var(--accent2); }
.q-ans .tbl { width: 100%; border-collapse: collapse; font-size: 13px; margin: 10px 0; }
.q-ans .tbl th {
  background: rgba(255,255,255,.05);
  color: var(--accent);
  padding: 8px 12px;
  text-align: left;
  font-size: 11px;
  text-transform: uppercase;
}
.q-ans .tbl td { padding: 8px 12px; border-bottom: 1px solid var(--border); }
.or-div {
  text-align: center;
  color: var(--muted);
  font-weight: 700;
  letter-spacing: 2px;
  margin: 16px 0;
  font-size: 13px;
}
.or-div span { background: var(--bg); padding: 0 12px; }
.or-line { border-top: 1px solid var(--border); }

/* ══════════════════════════════
   LIST STYLES
   ══════════════════════════════ */
.topic-body ul { margin-left: 18px; color: #c5cfe0; font-size: 15px; }
.topic-body ul li { margin-bottom: 5px; }
.topic-body ul li::marker { color: var(--uc, var(--accent)); }

/* ══════════════════════════════
   FOOTER (from sqta.html)
   ══════════════════════════════ */
footer {
  background: var(--surface);
  border-top: 1px solid var(--border);
  padding: 48px 0 0;
  margin-top: 60px;
}
footer .container {
  max-width: 1100px;
  padding-bottom: 0;
}
.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: 40px;
  margin-bottom: 40px;
}
.footer-brand p {
  color: var(--muted);
  font-size: 14px;
  line-height: 1.7;
  margin-top: 14px;
  max-width: 280px;
}
.footer-col h4 {
  font-family: 'JetBrains Mono', monospace;
  font-size: 12px;
  color: var(--accent);
  letter-spacing: 1px;
  text-transform: uppercase;
  margin-bottom: 16px;
}
.footer-col ul { list-style: none; }
.footer-col ul li { margin-bottom: 10px; }
.footer-col ul li a {
  color: var(--muted);
  text-decoration: none;
  font-size: 14px;
  transition: color 0.2s;
}
.footer-col ul li a:hover { color: var(--text); }
.footer-bottom {
  border-top: 1px solid var(--border);
  padding: 20px 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
}
.footer-bottom p {
  color: var(--muted);
  font-size: 13px;
}
.footer-bottom span { color: var(--text); font-weight: 600; }
.footer-social {
  display: flex;
  gap: 10px;
  align-items: center;
}
.footer-social a {
  width: 32px; height: 32px;
  border: 1px solid var(--border);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--muted);
  text-decoration: none;
  font-size: 14px;
  transition: all 0.2s;
}
.footer-social a:hover {
  border-color: var(--accent);
  color: var(--accent);
}

/* ══════════════════════════════
   SCROLLBAR
   ══════════════════════════════ */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: var(--bg); }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }

/* ══════════════════════════════
   RESPONSIVE
   ══════════════════════════════ */
@media (max-width: 768px) {
  .footer-grid {
    grid-template-columns: 1fr;
    gap: 28px;
  }
  .footer-brand p { max-width: 100%; }
}

@media (max-width: 600px) {
  .hero { margin-top: 58px; } /* no unit-nav on mobile — collapse both */
  .hero h1 { font-size: 28px; }
  nav.unit-nav { display: none; }
  .comp-table { font-size: 12px; }
  .comp-table th, .comp-table td { padding: 8px 10px; }
  .footer-bottom { flex-direction: column; text-align: center; }
}