/* ===== Glass layer: frosted surfaces, aurora background, richer motion ===== */
:root {
  --glass: color-mix(in srgb, #ffffff 58%, transparent);
  --glass-strong: color-mix(in srgb, #ffffff 74%, transparent);
  --glass-line: rgba(255, 255, 255, .75);
  --glass-shadow: 0 10px 40px rgba(31, 41, 64, .12), inset 0 1px 0 rgba(255, 255, 255, .8);
  --grad: linear-gradient(120deg, #d52b1e, #ff6a3d 55%, #ffb347);
  --grad-cool: linear-gradient(120deg, #3f7be0, #7b5cff);
  --aurora-1: #ff5a4a; --aurora-2: #ffb347; --aurora-3: #5b8cff; --aurora-4: #19c3a6;
  --dots: rgba(20, 30, 50, .07);
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --glass: color-mix(in srgb, #1b2430 55%, transparent);
    --glass-strong: color-mix(in srgb, #1b2430 78%, transparent);
    --glass-line: rgba(255, 255, 255, .12);
    --glass-shadow: 0 10px 40px rgba(0, 0, 0, .35), inset 0 1px 0 rgba(255, 255, 255, .07);
    --dots: rgba(255, 255, 255, .05);
  }
}
:root[data-theme="dark"] {
  --glass: color-mix(in srgb, #1b2430 55%, transparent);
  --glass-strong: color-mix(in srgb, #1b2430 78%, transparent);
  --glass-line: rgba(255, 255, 255, .12);
  --glass-shadow: 0 10px 40px rgba(0, 0, 0, .35), inset 0 1px 0 rgba(255, 255, 255, .07);
  --dots: rgba(255, 255, 255, .05);
}

/* aurora background */
body { background: var(--bg); background-image: radial-gradient(var(--dots) 1px, transparent 1px); background-size: 22px 22px; }
.bg-orbs span { opacity: .32; filter: blur(90px); }
.bg-orbs span:nth-child(1) { background: var(--aurora-1); }
.bg-orbs span:nth-child(2) { background: var(--aurora-2); }
.bg-orbs span:nth-child(3) { background: var(--aurora-3); opacity: .22; width: 38vmax; height: 38vmax; }
.bg-orbs::after { content: ''; position: absolute; width: 34vmax; height: 34vmax; border-radius: 50%; background: var(--aurora-4); filter: blur(100px); opacity: .14; top: 55%; inset-inline-start: -8vmax; animation: orb 34s ease-in-out infinite alternate-reverse; }
.spot { position: fixed; inset: 0; pointer-events: none; z-index: -1; background: radial-gradient(500px circle at var(--sx, 50%) var(--sy, 30%), color-mix(in srgb, var(--red) 9%, transparent), transparent 60%); }

/* scroll progress */
.scrollbar { position: fixed; top: 0; inset-inline: 0; height: 3px; z-index: 60; background: var(--grad); transform-origin: 0 50%; transform: scaleX(var(--sp, 0)); }
html[dir="rtl"] .scrollbar { transform-origin: 100% 50%; }

/* frosted surfaces */
.card, .panel, .stat, .scen, .sign-front, .sign-back, .check, .timeline li > div, .table-wrap, .exam-bar, .hero {
  background: var(--glass);
  -webkit-backdrop-filter: blur(18px) saturate(1.5); backdrop-filter: blur(18px) saturate(1.5);
  border: 1px solid var(--glass-line);
  box-shadow: var(--glass-shadow);
}
.topbar { background: var(--glass-strong); border-bottom: 1px solid var(--glass-line); }
.provbar { background: linear-gradient(90deg, rgba(213,43,30,.92), rgba(255,106,61,.88)); -webkit-backdrop-filter: blur(10px); backdrop-filter: blur(10px); }
.opt, .facts li, .num, .tips li, .stage, .callchip, .qn { background: color-mix(in srgb, var(--glass-strong) 80%, transparent); border-color: var(--glass-line); }
table { background: transparent; }
th { background: color-mix(in srgb, var(--glass-strong) 70%, transparent); }

/* gradient ring on hover */
.link-card, .sign-front, .scen, .anim { position: relative; }
.link-card::after, .anim::after {
  content: ''; position: absolute; inset: 0; border-radius: inherit; padding: 1.5px; pointer-events: none;
  background: var(--grad); -webkit-mask: linear-gradient(#000 0 0) content-box, linear-gradient(#000 0 0); -webkit-mask-composite: xor; mask-composite: exclude;
  opacity: 0; transition: opacity .3s;
}
.link-card:hover::after, .anim:hover::after { opacity: 1; }
.link-card:hover { box-shadow: 0 18px 50px rgba(213, 43, 30, .18), var(--glass-shadow); }

/* icon tiles */
.card-ico { background: var(--grad); color: #fff; box-shadow: 0 8px 22px rgba(213, 43, 30, .35); position: relative; overflow: hidden; }
.card-ico::after { content: ''; position: absolute; inset: -40%; background: linear-gradient(120deg, transparent 40%, rgba(255,255,255,.55) 50%, transparent 60%); transform: translateX(-100%); }
.link-card:hover .card-ico::after { animation: sweep .9s ease; }
.link-card:hover .card-ico { animation: hop .5s ease; }
@keyframes sweep { to { transform: translateX(100%); } }
@keyframes hop { 40% { transform: translateY(-5px) rotate(-6deg); } }
.card-ico.sm { box-shadow: 0 5px 14px rgba(213, 43, 30, .3); }

/* buttons */
.btn.primary { background: var(--grad); background-size: 160% 100%; border: 0; position: relative; overflow: hidden; transition: background-position .4s, transform .15s, box-shadow .3s; }
.btn.primary:hover { background-position: 100% 0; box-shadow: 0 10px 28px rgba(213, 43, 30, .4); }
.btn.primary::before { content: ''; position: absolute; inset: 0; background: linear-gradient(120deg, transparent 30%, rgba(255,255,255,.45) 50%, transparent 70%); transform: translateX(-120%); }
.btn.primary:hover::before { transition: transform .7s; transform: translateX(120%); }
.btn.ghost { background: var(--glass); -webkit-backdrop-filter: blur(10px); backdrop-filter: blur(10px); border-color: var(--glass-line); }
.lang-btn.on { background: var(--grad); }
.nav a.active { background: var(--grad); color: #fff; box-shadow: 0 6px 16px rgba(213,43,30,.28); }
.nav a.nav-sos { color: var(--red); }
.nav a.active.nav-sos { color: #fff; }

/* headings */
.page-head h1, .hero h1 { background: linear-gradient(100deg, var(--text) 20%, var(--red) 60%, #ff8a3d); -webkit-background-clip: text; background-clip: text; color: transparent; }
.shine { animation: none; }
.sec-title { position: relative; padding-bottom: 8px; }
.sec-title::after { content: ''; position: absolute; bottom: 0; inset-inline-start: 0; width: 56px; height: 4px; border-radius: 4px; background: var(--grad); transform-origin: 0 50%; transform: scaleX(0); transition: transform .8s cubic-bezier(.2,.8,.2,1) .2s; }
.sec-title.in::after, .sec-title:not(.rv)::after { transform: scaleX(1); }

/* hero */
.hero { border-radius: 32px; padding: 40px; background: linear-gradient(140deg, color-mix(in srgb, var(--glass-strong) 90%, transparent), var(--glass)); }
.hero h1 { font-size: clamp(2rem, 4.6vw, 3.4rem); }
.hero-art { perspective: 900px; }
.scene-hero { transform: rotateX(var(--hx, 0deg)) rotateY(var(--hy, 0deg)); transition: transform .3s ease; box-shadow: 0 30px 60px rgba(16,24,40,.25); }
.badge { background: var(--glass-strong); border: 1px solid var(--glass-line); }
.stat b { background: var(--grad); -webkit-background-clip: text; background-clip: text; color: transparent; }

/* page entry */
.page { animation: pagein .4s cubic-bezier(.2,.8,.2,1); }
@keyframes pagein { from { opacity: 0; transform: translateY(10px); } }

/* video-style lesson player */
.anim { padding: 0; overflow: hidden; }
.anim > h3 { padding: 16px 18px 0; display: flex; align-items: center; gap: 8px; }
.anim > h3::before { content: '▶'; display: inline-grid; place-items: center; width: 26px; height: 26px; border-radius: 50%; background: var(--grad); color: #fff; font-size: 11px; }
.anim .stage-wrap { margin: 12px 14px 0; position: relative; border-radius: 16px; background: #0d1219; box-shadow: inset 0 0 0 1px rgba(255,255,255,.06); }
.anim .stage-wrap .scene { border-radius: 16px; }
.anim .caption { margin: 0; padding: 12px 18px 4px; min-height: 5em; }
.anim .anim-ctl, .anim .dots-nav { padding: 0 14px; }
.anim .dots-nav { padding-bottom: 16px; }
.timeline-bar { display: flex; gap: 4px; margin: 10px 14px 0; }
.timeline-bar i { flex: 1; height: 4px; border-radius: 4px; background: var(--line); overflow: hidden; }
.timeline-bar i b { display: block; height: 100%; width: 0; background: var(--grad); }
.timeline-bar i.done b { width: 100%; }
.anim.playing .timeline-bar i.cur b { animation: fillbar 3.8s linear forwards; }
.anim:not(.playing) .timeline-bar i.cur b { width: 100%; opacity: .6; }
@keyframes fillbar { from { width: 0; } to { width: 100%; } }
.big-play { position: absolute; inset: 0; margin: auto; width: 64px; height: 64px; border-radius: 50%; border: 0; background: rgba(255,255,255,.18); -webkit-backdrop-filter: blur(8px); backdrop-filter: blur(8px); color: #fff; font-size: 24px; cursor: pointer; transition: transform .2s, opacity .3s; box-shadow: 0 0 0 2px rgba(255,255,255,.35); }
.big-play:hover { transform: scale(1.1); }
.anim.playing .big-play { opacity: 0; pointer-events: none; }
.subtitle { position: absolute; inset-inline: 10px; top: 8px; padding: 4px 10px; border-radius: 10px; background: rgba(0,0,0,.6); color: #fff; font-size: .74rem; line-height: 1.45; text-align: center; opacity: 0; transition: opacity .3s; pointer-events: none; }
.anim.playing .subtitle { opacity: 1; }
.anim.playing .caption { opacity: .55; }

/* official videos */
.vlinks { grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); }
.vlink { display: flex; gap: 14px; align-items: center; text-decoration: none; color: var(--text); }
.vlink .vthumb { flex: none; width: 92px; height: 60px; border-radius: 12px; display: grid; place-items: center; background: linear-gradient(135deg, #1d232b, #3a2230); color: #fff; font-size: 22px; position: relative; overflow: hidden; }
.vlink .vthumb::after { content: ''; position: absolute; inset: 0; background: linear-gradient(120deg, transparent 30%, rgba(255,255,255,.25) 50%, transparent 70%); transform: translateX(-100%); }
.vlink:hover .vthumb::after { transition: transform .8s; transform: translateX(100%); }
.vlink small { color: var(--muted); display: block; }

/* pick-the-sign questions */
.opts.imgs { grid-template-columns: repeat(2, 1fr); }
.opts.imgs .opt { justify-content: center; padding: 14px; }
.opts.imgs .opt svg { width: 84px; height: 84px; }
.opts.imgs .opt-l { position: absolute; top: 8px; inset-inline-start: 8px; }
.opts.imgs .opt { position: relative; min-height: 112px; }
.rev-ok svg, .rev-no svg { width: 34px; height: 34px; vertical-align: middle; }

@media (max-width: 760px) {
  .hero { padding: 22px; }
  .opts.imgs .opt svg { width: 64px; height: 64px; }
}
@media (prefers-reduced-motion: reduce) {
  .page { animation: none; }
  .scene-hero { transform: none !important; }
}
@supports not ((backdrop-filter: blur(1px)) or (-webkit-backdrop-filter: blur(1px))) {
  .card, .panel, .stat, .scen, .sign-front, .sign-back, .check, .timeline li > div, .hero { background: var(--card); }
}