:root {
  --bg: #050607;
  --ink: #f2f8f7;
  --muted: rgba(226, 241, 239, 0.58);
  --cyan: #20d9e8;
  --green: #a6ff4d;
}

* { box-sizing: border-box; }

html {
  background: var(--bg);
}

body {
  margin: 0;
  overflow: hidden;
  background: var(--bg);
  color: var(--ink);
  font-family: Inter, "Noto Sans SC", "Microsoft YaHei", Arial, sans-serif;
}

button, a { font: inherit; }
.experience { min-height: 100vh; background: var(--bg); }

.film-canvas,
.cinematic-vignette {
  position: fixed;
  inset: 0;
  width: 100%;
  height: 100%;
}

.film-canvas { z-index: 1; }

.cinematic-vignette {
  z-index: 2;
  pointer-events: none;
  background:
    linear-gradient(90deg, rgba(3, 5, 6, 0.48), transparent 36%, transparent 72%, rgba(3, 5, 6, 0.18)),
    linear-gradient(180deg, rgba(3, 5, 6, 0.3), transparent 24%, transparent 72%, rgba(3, 5, 6, 0.62));
}

.brand-hud {
  position: fixed;
  z-index: 8;
  top: 26px;
  left: 32px;
  display: flex;
  align-items: center;
  gap: 16px;
  min-width: 250px;
  min-height: 62px;
  isolation: isolate;
}

.brand-hud::before {
  content: "";
  position: absolute;
  z-index: -1;
  inset: -26px -90px -30px -32px;
  background: linear-gradient(90deg, #050607 0%, #050607 58%, rgba(5, 6, 7, 0.92) 72%, transparent 100%);
  pointer-events: none;
}

.brand-lockup { display: flex; align-items: baseline; gap: 7px; letter-spacing: -0.04em; }
.brand-name, .brand-model { font-size: 19px; font-weight: 800; }
.brand-model { color: var(--green); }

.brand-meta {
  color: var(--muted);
  font-family: ui-monospace, SFMono-Regular, Consolas, monospace;
  font-size: 9px;
  letter-spacing: 0.12em;
}

.frame-counter {
  position: fixed;
  z-index: 7;
  top: 30px;
  right: 32px;
  display: flex;
  align-items: center;
  gap: 9px;
  color: rgba(238, 248, 247, 0.52);
  font-family: ui-monospace, SFMono-Regular, Consolas, monospace;
  font-size: 10px;
  letter-spacing: 0.08em;
}

.frame-counter i { display: block; width: 34px; height: 1px; background: linear-gradient(90deg, var(--cyan), var(--green)); }

.caption {
  position: fixed;
  z-index: 6;
  top: 50%;
  width: min(620px, 46vw);
  transform: translateY(-50%);
  text-shadow: 0 2px 22px rgba(0, 0, 0, 0.72);
  opacity: 1;
  transition: opacity 320ms ease, left 500ms ease, right 500ms ease, bottom 500ms ease, width 500ms ease;
  pointer-events: none;
}

.caption.is-playing { opacity: 0; }

.caption-left { left: 7vw; }
.caption-right { right: 7vw; }

.caption-center {
  top: auto;
  bottom: 7vh;
  left: 50%;
  width: min(900px, 82vw);
  transform: translateX(-50%);
  text-align: center;
}

.caption-eyebrow {
  margin: 0 0 18px;
  color: var(--green);
  font-family: ui-monospace, SFMono-Regular, Consolas, monospace;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.18em;
}

.caption-heading-row { display: flex; align-items: flex-end; gap: 28px; }
.caption-right .caption-heading-row { justify-content: flex-end; }
.caption-center .caption-heading-row { justify-content: center; }

.caption h1 {
  margin: 0;
  white-space: pre-line;
  font-size: clamp(42px, 5.3vw, 92px);
  font-weight: 780;
  letter-spacing: -0.075em;
  line-height: 0.84;
}

.caption-zh {
  max-width: 150px;
  margin: 0 0 3px;
  color: rgba(238, 248, 247, 0.74);
  font-size: 12px;
  letter-spacing: 0.12em;
  line-height: 1.75;
}

.spec-pair {
  display: flex;
  gap: 22px;
  margin-top: 26px;
  color: rgba(238, 248, 247, 0.75);
  font-family: ui-monospace, SFMono-Regular, Consolas, monospace;
  font-size: 10px;
  letter-spacing: 0.13em;
}

.caption-right .spec-pair, .caption-center .spec-pair { justify-content: center; }

.spec-pair span::before {
  content: "";
  display: inline-block;
  width: 5px;
  height: 5px;
  margin-right: 8px;
  border-radius: 50%;
  background: var(--cyan);
  box-shadow: 0 0 12px var(--cyan);
}

.spec-pair span:last-child::before { background: var(--green); box-shadow: 0 0 12px var(--green); }

.concept-note {
  margin: 14px 0 0;
  color: rgba(238, 248, 247, 0.38);
  font-family: ui-monospace, SFMono-Regular, Consolas, monospace;
  font-size: 9px;
  letter-spacing: 0.16em;
}

.chapter-nav {
  position: fixed;
  z-index: 8;
  right: 30px;
  top: 50%;
  display: grid;
  gap: 14px;
  transform: translateY(-50%);
}

.chapter-dot {
  display: flex;
  width: 30px;
  height: 16px;
  align-items: center;
  justify-content: flex-end;
  border: 0;
  padding: 0;
  color: rgba(238, 248, 247, 0.34);
  background: transparent;
  cursor: pointer;
}

.chapter-dot::after {
  content: "";
  width: 5px;
  height: 5px;
  margin-left: 8px;
  border-radius: 50%;
  background: currentColor;
  transition: transform 250ms ease, color 250ms ease, box-shadow 250ms ease;
}

.chapter-dot span { opacity: 0; font: 9px ui-monospace, SFMono-Regular, Consolas, monospace; transition: opacity 250ms ease; }
.chapter-dot:hover span, .chapter-dot.is-active span { opacity: 1; }
.chapter-dot.is-active { color: var(--green); }
.chapter-dot.is-active::after { transform: scale(1.65); box-shadow: 0 0 12px var(--green); }
.chapter-dot:disabled { cursor: wait; }

.scroll-hint {
  position: fixed;
  z-index: 7;
  left: 32px;
  bottom: 28px;
  display: flex;
  align-items: center;
  gap: 12px;
  color: rgba(238, 248, 247, 0.46);
  font-family: ui-monospace, SFMono-Regular, Consolas, monospace;
  font-size: 9px;
  letter-spacing: 0.16em;
}

.scroll-hint i { display: block; width: 54px; height: 1px; overflow: hidden; background: rgba(255, 255, 255, 0.22); }
.scroll-hint i::after { content: ""; display: block; width: 22px; height: 1px; background: var(--green); animation: scan 1.8s ease-in-out infinite; }

@keyframes scan { from { transform: translateX(-22px); } to { transform: translateX(56px); } }

.preloader {
  position: fixed;
  z-index: 20;
  inset: 0;
  display: grid;
  place-items: center;
  background: radial-gradient(circle at 60% 45%, rgba(32, 217, 232, 0.09), transparent 34%), #050607;
  transition: opacity 700ms ease, visibility 700ms ease;
}

.preloader.is-hidden { opacity: 0; visibility: hidden; pointer-events: none; }
.preloader-mark { position: absolute; top: 28px; left: 32px; color: rgba(238, 248, 247, 0.5); font: 10px ui-monospace, SFMono-Regular, Consolas, monospace; letter-spacing: 0.16em; }
.preloader-center { width: min(420px, calc(100vw - 48px)); text-align: center; }
.preloader-center p { margin: 0 0 8px; color: var(--green); font: 11px ui-monospace, SFMono-Regular, Consolas, monospace; letter-spacing: 0.26em; }
.preloader-center strong { display: block; font-size: clamp(88px, 15vw, 176px); font-weight: 750; letter-spacing: -0.09em; line-height: 0.9; }
.load-bar { height: 1px; margin: 34px 0 16px; background: rgba(255, 255, 255, 0.14); }
.load-bar i { display: block; height: 1px; background: linear-gradient(90deg, var(--cyan), var(--green)); box-shadow: 0 0 14px rgba(166, 255, 77, 0.7); transition: width 120ms linear; }
.preloader-center > span { display: block; color: rgba(238, 248, 247, 0.45); font: 9px ui-monospace, SFMono-Regular, Consolas, monospace; letter-spacing: 0.17em; }

.preloader button {
  margin-top: 28px;
  border: 1px solid rgba(166, 255, 77, 0.55);
  padding: 13px 20px;
  color: var(--bg);
  background: var(--green);
  font: 10px ui-monospace, SFMono-Regular, Consolas, monospace;
  letter-spacing: 0.13em;
  cursor: pointer;
  transition: opacity 180ms ease, transform 180ms ease;
}

.preloader button:disabled { opacity: 0.3; cursor: wait; }
.preloader button:not(:disabled):hover { transform: translateY(-2px); }

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
}

@media (max-width: 820px) {
  .brand-hud { top: 16px; left: 18px; }
  .brand-meta { display: none; }
  .frame-counter { top: 21px; right: 18px; }
  .chapter-nav { right: 14px; }
  .caption, .caption-left, .caption-right, .caption-center {
    top: auto;
    right: auto;
    bottom: 11vh;
    left: 22px;
    width: calc(100vw - 62px);
    transform: none;
    text-align: left;
  }
  .caption-heading-row, .caption-right .caption-heading-row, .caption-center .caption-heading-row { display: block; }
  .caption h1 { font-size: clamp(40px, 13vw, 66px); }
  .caption-zh { max-width: none; margin-top: 14px; }
  .caption-right .spec-pair, .caption-center .spec-pair { justify-content: flex-start; }
  .spec-pair { flex-wrap: wrap; gap: 10px 18px; }
  .scroll-hint { left: 22px; bottom: 22px; }
}

@media (prefers-reduced-motion: reduce) {
  .scroll-hint i::after { animation: none; }
  .preloader, .caption { transition: none; }
}