/* =====================================================
   lectures.physicsgurukul.com — Global Stylesheet
   Design: Dark-science editorial with warm amber accents
   ===================================================== */

@import url('https://fonts.googleapis.com/css2?family=Space+Grotesk:wght@300;400;500;600;700&family=DM+Serif+Display:ital@0;1&family=JetBrains+Mono:wght@400;500&display=swap');

/* Intentional override: physicsgurukul loads Lora/Gentium/JetBrains globally,
   but this subdomain uses its own fonts for distinct identity. */

:root {
  /* Core palette — deep navy science lab */
  --bg:           #0a0d14;
  --bg-2:         #0f1422;
  --bg-3:         #151b2e;
  --surface:      #1a2238;
  --surface-2:    #1f2a42;
  --border:       rgba(255,255,255,0.08);
  --border-accent:rgba(255,185,0,0.3);

  /* Typography */
  --text:         #e8eaf2;
  --text-muted:   #8892aa;
  --text-dim:     #5a6480;

  /* Brand accents */
  --amber:        #ffb900;
  --amber-light:  #ffd055;
  --amber-dim:    rgba(255,185,0,0.15);
  --amber-glow:   rgba(255,185,0,0.06);
  --red:          #ff4757;
  --teal:         #00d2c6;
  --blue:         #4a9fff;

  /* Fonts */
  --font-display: 'DM Serif Display', Georgia, serif;
  --font-body:    'Space Grotesk', sans-serif;
  --font-mono:    'JetBrains Mono', monospace;

  /* Sizing */
  --max-w:        1200px;
  --radius:       12px;
  --radius-sm:    8px;
  --nav-h:        64px;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; }

body {
  font-family: var(--font-body);
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

/* ── NOISE TEXTURE OVERLAY ── */
body::before {
  content: '';
  position: fixed;
  inset: 0;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noise'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noise)' opacity='0.04'/%3E%3C/svg%3E");
  pointer-events: none;
  z-index: 0;
  opacity: 0.4;
}

/* ── SCROLLBAR ── */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: var(--bg); }
::-webkit-scrollbar-thumb { background: var(--surface-2); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--amber); }

/* ══════════════════════════════════
   NAVIGATION
══════════════════════════════════ */
.pg-nav {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--nav-h);
  background: rgba(10,13,20,0.92);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
}

.pg-nav__inner {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 24px;
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.pg-nav__brand {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
}

.pg-nav__logo-icon {
  width: 32px;
  height: 32px;
  background: var(--amber);
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 18px;
  flex-shrink: 0;
}

.pg-nav__brand-text {
  display: flex;
  flex-direction: column;
  line-height: 1.1;
}

.pg-nav__brand-name {
  font-family: var(--font-display);
  font-size: 17px;
  color: var(--text);
  letter-spacing: 0.01em;
}

.pg-nav__brand-sub {
  font-size: 10px;
  color: var(--amber);
  letter-spacing: 0.12em;
  text-transform: uppercase;
  font-weight: 500;
}

.pg-nav__links {
  display: flex;
  align-items: center;
  gap: 4px;
  list-style: none;
}

.pg-nav__links a {
  color: var(--text-muted);
  text-decoration: none;
  font-size: 14px;
  font-weight: 500;
  padding: 6px 14px;
  border-radius: var(--radius-sm);
  transition: color 0.2s, background 0.2s;
}

.pg-nav__links a:hover,
.pg-nav__links a.active { color: var(--text); background: var(--surface); }

.pg-nav__cta {
  background: var(--amber);
  color: var(--bg) !important;
  font-weight: 700 !important;
  border-radius: var(--radius-sm) !important;
  padding: 7px 16px !important;
  transition: background 0.2s, transform 0.2s !important;
}

.pg-nav__cta:hover { background: var(--amber-light) !important; transform: translateY(-1px); }

/* ══════════════════════════════════
   BREADCRUMB
══════════════════════════════════ */
.pg-breadcrumb {
  padding: 14px 24px;
  max-width: var(--max-w);
  margin: 0 auto;
  font-size: 13px;
  color: var(--text-dim);
  display: flex;
  align-items: center;
  gap: 6px;
  flex-wrap: wrap;
}

.pg-breadcrumb a { color: var(--text-muted); text-decoration: none; transition: color 0.2s; }
.pg-breadcrumb a:hover { color: var(--amber); }
.pg-breadcrumb__sep { color: var(--text-dim); font-size: 11px; }
.pg-breadcrumb__current { color: var(--text); }

/* ══════════════════════════════════
   HERO SECTIONS
══════════════════════════════════ */
.pg-hero {
  position: relative;
  overflow: hidden;
  padding: 72px 24px 60px;
  text-align: center;
}

.pg-hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background: radial-gradient(ellipse 80% 60% at 50% -10%, rgba(255,185,0,0.12) 0%, transparent 70%);
  pointer-events: none;
}

.pg-hero__eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: var(--amber-dim);
  border: 1px solid var(--border-accent);
  border-radius: 999px;
  padding: 5px 14px;
  font-size: 12px;
  font-weight: 600;
  color: var(--amber);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: 20px;
}

.pg-hero__title {
  font-family: var(--font-display);
  font-size: clamp(2rem, 5vw, 3.6rem);
  line-height: 1.15;
  color: var(--text);
  max-width: 800px;
  margin: 0 auto 16px;
}

.pg-hero__title em {
  font-style: italic;
  color: var(--amber);
}

.pg-hero__desc {
  font-size: 17px;
  color: var(--text-muted);
  max-width: 600px;
  margin: 0 auto 32px;
  line-height: 1.7;
}

.pg-hero__stats {
  display: flex;
  justify-content: center;
  gap: 40px;
  flex-wrap: wrap;
}

.pg-hero__stat {
  display: flex;
  flex-direction: column;
  align-items: center;
}

.pg-hero__stat-num {
  font-family: var(--font-display);
  font-size: 2rem;
  color: var(--amber);
  line-height: 1;
}

.pg-hero__stat-label {
  font-size: 12px;
  color: var(--text-dim);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-top: 4px;
}

/* ══════════════════════════════════
   GRID SYSTEMS
══════════════════════════════════ */
.pg-container {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 24px;
}

.pg-section {
  padding: 48px 0;
}

.pg-section__header {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  margin-bottom: 28px;
  gap: 16px;
  flex-wrap: wrap;
}

.pg-section__title {
  font-family: var(--font-display);
  font-size: 1.6rem;
  color: var(--text);
}

.pg-section__title::before {
  content: '//';
  font-family: var(--font-mono);
  font-size: 1rem;
  color: var(--amber);
  margin-right: 10px;
  opacity: 0.8;
}

.pg-section__link {
  font-size: 13px;
  color: var(--amber);
  text-decoration: none;
  font-weight: 500;
  letter-spacing: 0.04em;
}

.pg-section__link:hover { text-decoration: underline; }

/* ── Class Cards (home page) ── */
.pg-class-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 20px;
}

.pg-class-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px;
  text-decoration: none;
  display: flex;
  flex-direction: column;
  gap: 12px;
  transition: border-color 0.25s, transform 0.25s, box-shadow 0.25s;
  position: relative;
  overflow: hidden;
}

.pg-class-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--amber), var(--teal));
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.3s;
}

.pg-class-card:hover {
  border-color: var(--border-accent);
  transform: translateY(-4px);
  box-shadow: 0 20px 40px rgba(0,0,0,0.4), 0 0 0 1px rgba(255,185,0,0.1);
}

.pg-class-card:hover::before { transform: scaleX(1); }

.pg-class-card__num {
  font-family: var(--font-display);
  font-size: 3.5rem;
  color: rgba(255,185,0,0.12);
  line-height: 1;
  position: absolute;
  right: 20px;
  top: 16px;
}

.pg-class-card__label {
  font-size: 11px;
  font-weight: 700;
  color: var(--amber);
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.pg-class-card__title {
  font-family: var(--font-display);
  font-size: 1.5rem;
  color: var(--text);
}

.pg-class-card__meta {
  font-size: 13px;
  color: var(--text-muted);
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}

.pg-class-card__meta span {
  display: flex;
  align-items: center;
  gap: 5px;
}

/* ── Module Cards (class hub) ── */
.pg-module-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 20px;
}

.pg-module-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  text-decoration: none;
  display: flex;
  gap: 18px;
  align-items: flex-start;
  transition: border-color 0.25s, transform 0.2s, box-shadow 0.25s;
}

.pg-module-card:hover {
  border-color: var(--border-accent);
  transform: translateY(-3px);
  box-shadow: 0 16px 32px rgba(0,0,0,0.35);
}

.pg-module-card__icon {
  width: 48px;
  height: 48px;
  background: var(--amber-dim);
  border: 1px solid var(--border-accent);
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 22px;
  flex-shrink: 0;
}

.pg-module-card__body { flex: 1; }

.pg-module-card__title {
  font-family: var(--font-display);
  font-size: 1.2rem;
  color: var(--text);
  margin-bottom: 6px;
}

.pg-module-card__desc {
  font-size: 13px;
  color: var(--text-muted);
  line-height: 1.5;
  margin-bottom: 10px;
}

.pg-module-card__chips {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}

.pg-chip {
  background: var(--bg-3);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 3px 10px;
  font-size: 11px;
  color: var(--text-muted);
  font-family: var(--font-mono);
}

.pg-chip--amber { background: var(--amber-dim); border-color: var(--border-accent); color: var(--amber); }
.pg-chip--teal { background: rgba(0,210,198,0.1); border-color: rgba(0,210,198,0.3); color: var(--teal); }
.pg-chip--blue { background: rgba(74,159,255,0.1); border-color: rgba(74,159,255,0.3); color: var(--blue); }

/* ── Chapter List (module hub) ── */
.pg-chapter-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.pg-chapter-item {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px 24px;
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 18px;
  transition: border-color 0.2s, background 0.2s;
}

.pg-chapter-item:hover {
  border-color: var(--border-accent);
  background: var(--surface-2);
}

.pg-chapter-item__num {
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--amber);
  min-width: 32px;
  font-weight: 500;
}

.pg-chapter-item__title {
  font-size: 15px;
  font-weight: 600;
  color: var(--text);
  flex: 1;
}

.pg-chapter-item__meta {
  font-size: 12px;
  color: var(--text-muted);
  display: flex;
  align-items: center;
  gap: 4px;
  white-space: nowrap;
}

.pg-chapter-item__arrow {
  color: var(--text-dim);
  font-size: 14px;
  transition: transform 0.2s, color 0.2s;
}

.pg-chapter-item:hover .pg-chapter-item__arrow {
  transform: translateX(4px);
  color: var(--amber);
}

/* ══════════════════════════════════
   LECTURE PAGE LAYOUT
══════════════════════════════════ */
.pg-lecture-layout {
  display: grid;
  grid-template-columns: 1fr 340px;
  gap: 28px;
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 24px 24px 60px;
  align-items: start;
}

/* ── Video Player ── */
.pg-player {
  background: #000;
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--border);
  box-shadow: 0 24px 64px rgba(0,0,0,0.6);
}

.pg-player__frame {
  position: relative;
  width: 100%;
  padding-bottom: 56.25%;
  background: #000;
}

.pg-player__frame iframe {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  border: none;
}

.pg-player__info {
  padding: 24px;
}

.pg-player__title {
  font-family: var(--font-display);
  font-size: 1.65rem;
  color: var(--text);
  line-height: 1.25;
  margin-bottom: 12px;
}

.pg-player__meta {
  display: flex;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
  margin-bottom: 16px;
}

.pg-player__meta-item {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 13px;
  color: var(--text-muted);
}

.pg-player__meta-item svg { color: var(--amber); }

.pg-player__tags {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
  margin-bottom: 16px;
}

.pg-player__desc {
  font-size: 15px;
  color: var(--text-muted);
  line-height: 1.7;
  padding-top: 16px;
  border-top: 1px solid var(--border);
}

/* ── Prev/Next Navigation ── */
.pg-lecture-nav {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin-top: 20px;
  padding-top: 20px;
  border-top: 1px solid var(--border);
}

.pg-lecture-nav__btn {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 14px 18px;
  text-decoration: none;
  display: flex;
  flex-direction: column;
  gap: 4px;
  transition: border-color 0.2s, background 0.2s;
}

.pg-lecture-nav__btn:hover {
  border-color: var(--border-accent);
  background: var(--surface-2);
}

.pg-lecture-nav__btn--next { text-align: right; }

.pg-lecture-nav__label {
  font-size: 11px;
  color: var(--text-dim);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-weight: 600;
}

.pg-lecture-nav__title {
  font-size: 13px;
  font-weight: 600;
  color: var(--text-muted);
}

/* ── Sidebar ── */
.pg-sidebar { position: sticky; top: calc(var(--nav-h) + 16px); }

.pg-sidebar__panel {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
}

.pg-sidebar__header {
  padding: 16px 20px;
  border-bottom: 1px solid var(--border);
  background: var(--surface-2);
}

.pg-sidebar__title {
  font-size: 13px;
  font-weight: 700;
  color: var(--text);
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.pg-sidebar__sub {
  font-size: 11px;
  color: var(--text-dim);
  margin-top: 2px;
}

.pg-playlist { list-style: none; max-height: 480px; overflow-y: auto; }

.pg-playlist__item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 18px;
  border-bottom: 1px solid var(--border);
  text-decoration: none;
  transition: background 0.15s;
}

.pg-playlist__item:last-child { border-bottom: none; }

.pg-playlist__item:hover { background: var(--surface-2); }

.pg-playlist__item.active {
  background: var(--amber-dim);
  border-left: 3px solid var(--amber);
  padding-left: 15px;
}

.pg-playlist__num {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--text-dim);
  min-width: 20px;
}

.pg-playlist__item.active .pg-playlist__num { color: var(--amber); }

.pg-playlist__info { flex: 1; }

.pg-playlist__lecture-title {
  font-size: 13px;
  font-weight: 600;
  color: var(--text-muted);
  line-height: 1.3;
}

.pg-playlist__item.active .pg-playlist__lecture-title { color: var(--amber-light); }

.pg-playlist__duration {
  font-size: 11px;
  color: var(--text-dim);
  font-family: var(--font-mono);
  margin-top: 2px;
}

.pg-sidebar__extra {
  margin-top: 16px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px 20px;
}

.pg-sidebar__extra-title {
  font-size: 12px;
  font-weight: 700;
  color: var(--text-dim);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 12px;
}

.pg-sidebar__extra a {
  display: block;
  font-size: 13px;
  color: var(--blue);
  text-decoration: none;
  padding: 5px 0;
  border-bottom: 1px solid var(--border);
}

.pg-sidebar__extra a:last-child { border-bottom: none; }
.pg-sidebar__extra a:hover { color: var(--amber); }

/* ══════════════════════════════════
   LECTURE CARDS (chapter page)
══════════════════════════════════ */
.pg-lecture-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 20px;
}

.pg-lecture-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  text-decoration: none;
  transition: border-color 0.25s, transform 0.2s, box-shadow 0.25s;
  display: flex;
  flex-direction: column;
}

.pg-lecture-card:hover {
  border-color: var(--border-accent);
  transform: translateY(-4px);
  box-shadow: 0 20px 40px rgba(0,0,0,0.4);
}

.pg-lecture-card__thumb {
  position: relative;
  width: 100%;
  padding-bottom: 56.25%;
  background: var(--bg-3);
  overflow: hidden;
}

.pg-lecture-card__thumb img {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.4s;
}

.pg-lecture-card:hover .pg-lecture-card__thumb img { transform: scale(1.05); }

.pg-lecture-card__play {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(0,0,0,0.3);
  transition: background 0.2s;
}

.pg-lecture-card:hover .pg-lecture-card__play { background: rgba(0,0,0,0.1); }

.pg-play-btn {
  width: 52px;
  height: 52px;
  background: var(--amber);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 4px 20px rgba(255,185,0,0.5);
  transition: transform 0.2s, box-shadow 0.2s;
}

.pg-lecture-card:hover .pg-play-btn {
  transform: scale(1.1);
  box-shadow: 0 6px 28px rgba(255,185,0,0.7);
}

.pg-play-btn svg { fill: var(--bg); width: 20px; height: 20px; margin-left: 3px; }

.pg-lecture-card__duration-badge {
  position: absolute;
  bottom: 10px;
  right: 10px;
  background: rgba(0,0,0,0.85);
  border-radius: 4px;
  padding: 2px 8px;
  font-size: 11px;
  font-family: var(--font-mono);
  color: #fff;
}

.pg-lecture-card__body { padding: 16px; flex: 1; display: flex; flex-direction: column; gap: 8px; }

.pg-lecture-card__order {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--amber);
  font-weight: 500;
}

.pg-lecture-card__title {
  font-size: 15px;
  font-weight: 600;
  color: var(--text);
  line-height: 1.35;
}

.pg-lecture-card__desc {
  font-size: 13px;
  color: var(--text-muted);
  line-height: 1.5;
  flex: 1;
}

/* ══════════════════════════════════
   FOOTER
══════════════════════════════════ */
.pg-footer {
  background: var(--bg-2);
  border-top: 1px solid var(--border);
  padding: 48px 24px 28px;
  margin-top: 60px;
}

.pg-footer__inner {
  max-width: var(--max-w);
  margin: 0 auto;
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 40px;
  margin-bottom: 40px;
}

.pg-footer__brand-name {
  font-family: var(--font-display);
  font-size: 1.3rem;
  color: var(--text);
  margin-bottom: 10px;
}

.pg-footer__brand-desc {
  font-size: 13px;
  color: var(--text-dim);
  line-height: 1.6;
  max-width: 280px;
}

.pg-footer__col-title {
  font-size: 11px;
  font-weight: 700;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: 14px;
}

.pg-footer__links { list-style: none; display: flex; flex-direction: column; gap: 8px; }

.pg-footer__links a {
  font-size: 13px;
  color: var(--text-dim);
  text-decoration: none;
  transition: color 0.2s;
}

.pg-footer__links a:hover { color: var(--amber); }

.pg-footer__bottom {
  max-width: var(--max-w);
  margin: 0 auto;
  padding-top: 24px;
  border-top: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
}

.pg-footer__copy {
  font-size: 12px;
  color: var(--text-dim);
}

.pg-footer__copy a { color: var(--amber); text-decoration: none; }

.pg-footer__tag {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--text-dim);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 3px 8px;
}

/* ══════════════════════════════════
   DIVIDER
══════════════════════════════════ */
.pg-divider {
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--border), transparent);
  margin: 0 0 48px;
}

/* ══════════════════════════════════
   ANIMATIONS (page entry)
══════════════════════════════════ */
@keyframes pg-fadein-up {
  from { opacity: 0; transform: translateY(20px); }
  to   { opacity: 1; transform: translateY(0); }
}

.pg-animate {
  animation: pg-fadein-up 0.5s ease both;
}

.pg-animate--d1 { animation-delay: 0.05s; }
.pg-animate--d2 { animation-delay: 0.12s; }
.pg-animate--d3 { animation-delay: 0.20s; }
.pg-animate--d4 { animation-delay: 0.28s; }

/* ══════════════════════════════════
   RESPONSIVE
══════════════════════════════════ */
@media (max-width: 900px) {
  .pg-lecture-layout {
    grid-template-columns: 1fr;
    padding: 16px 16px 48px;
  }
  .pg-sidebar { position: static; }
  .pg-footer__inner { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 640px) {
  .pg-hero { padding: 48px 16px 40px; }
  .pg-hero__stats { gap: 24px; }
  .pg-nav__links { display: none; }
  .pg-lecture-grid { grid-template-columns: 1fr; }
  .pg-footer__inner { grid-template-columns: 1fr; }
  .pg-lecture-nav { grid-template-columns: 1fr; }
  .pg-lecture-nav__btn--next { text-align: left; }
}