:root {
  color-scheme: dark;
  --background: #050505;
  --foreground: #f2f2f0;
  --muted: #8f8f8c;
  --line: rgba(255, 255, 255, 0.72);
  --pair-duration: 2.2s;
}

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

html,
body {
  width: 100%;
  min-height: 100%;
  margin: 0;
  background: var(--background);
}

body {
  color: var(--foreground);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

.stage {
  position: relative;
  min-height: 100svh;
  overflow: hidden;
  isolation: isolate;
}

.language-layer--en {
  display: none;
}

html[data-language="en"] .language-layer--zh {
  display: none;
}

html[data-language="en"] .language-layer--en {
  display: block;
}

.divider {
  position: absolute;
  z-index: 1;
  top: 50%;
  left: 50%;
  width: 1px;
  height: clamp(11rem, 36vh, 20rem);
  background: var(--line);
  opacity: 0;
  transform: translate(-50%, -50%) scaleY(0);
  transform-origin: center;
}

.word-sequence,
.identity {
  position: absolute;
  z-index: 2;
  inset: 0;
}

.word-pair {
  position: absolute;
  top: 50%;
  left: 50%;
  width: min(72vw, 25rem);
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: clamp(4.5rem, 15vw, 9rem);
  opacity: 0;
  transform: translate(-50%, calc(-50% + 0.75rem));
  font-size: clamp(2rem, 5vw, 3.25rem);
  font-weight: 300;
  line-height: 1;
  letter-spacing: 0.08em;
}

.word-pair span:first-child {
  text-align: right;
}

.word-pair span:last-child {
  text-align: left;
}

.word-pair--en {
  width: min(78vw, 36rem);
  gap: clamp(4rem, 13vw, 9rem);
  font-size: clamp(1rem, 2.6vw, 1.45rem);
  font-weight: 300;
  letter-spacing: 0.2em;
  text-transform: uppercase;
}

.identity {
  display: grid;
  place-items: center;
  text-align: center;
  pointer-events: none;
}

.identity__core {
  position: relative;
  z-index: 3;
  padding: clamp(1.2rem, 3vh, 2rem) clamp(1.5rem, 5vw, 3.5rem);
  background: var(--background);
  opacity: 0;
  transform: translateY(0.75rem);
}

h1 {
  margin: 0;
  font-size: clamp(3.2rem, 9vw, 7.5rem);
  font-weight: 300;
  line-height: 1;
  letter-spacing: 0.16em;
  text-indent: 0.16em;
  white-space: nowrap;
}

.english-name {
  margin: clamp(1.1rem, 2.5vh, 1.6rem) 0 0;
  color: rgba(242, 242, 240, 0.78);
  font-size: clamp(0.72rem, 1.3vw, 0.95rem);
  font-weight: 400;
  letter-spacing: 0.24em;
  text-transform: uppercase;
}

.identity__core--en h1 {
  font-size: clamp(2.8rem, 7.5vw, 6.2rem);
  letter-spacing: 0.035em;
  text-indent: 0;
}

.signature {
  position: absolute;
  z-index: 3;
  top: 72%;
  left: 50%;
  width: 100%;
  color: rgba(242, 242, 240, 0.72);
  opacity: 0;
  transform: translate(-50%, 0.6rem);
}

.signature p {
  margin: 0;
}

.signature p:first-child {
  font-size: clamp(0.85rem, 1.5vw, 1rem);
  font-weight: 300;
  letter-spacing: 0.38em;
  text-indent: 0.38em;
}

.signature p:last-child {
  margin-top: 0.75rem;
  color: var(--muted);
  font-size: 0.62rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
}

.signature--en p:first-child {
  color: rgba(242, 242, 240, 0.72);
  font-size: clamp(0.72rem, 1.3vw, 0.9rem);
  letter-spacing: 0.2em;
  text-indent: 0;
  text-transform: uppercase;
}

footer {
  position: absolute;
  z-index: 3;
  right: 0;
  bottom: max(1.25rem, env(safe-area-inset-bottom));
  left: 0;
  color: #50504e;
  opacity: 0;
  font-size: 0.58rem;
  letter-spacing: 0.22em;
  text-align: center;
  text-transform: uppercase;
}

.animations-running .divider {
  animation: line-arrival 1.4s cubic-bezier(0.22, 1, 0.36, 1) 0.35s forwards;
}

.animations-running .word-pair {
  animation: pair-passage var(--pair-duration) ease-in-out
    calc(2.1s + var(--order) * var(--pair-duration)) forwards;
}

.animations-running .identity__core {
  animation: reveal 1.8s cubic-bezier(0.22, 1, 0.36, 1) 11.7s forwards;
}

.animations-running .signature {
  animation: signature-reveal 1.5s ease-out 12.7s forwards;
}

.animations-running footer {
  animation: soft-reveal 1.2s ease-out 13.5s forwards;
}

@keyframes line-arrival {
  to {
    opacity: 1;
    transform: translate(-50%, -50%) scaleY(1);
  }
}

@keyframes pair-passage {
  0% {
    opacity: 0;
    transform: translate(-50%, calc(-50% + 0.75rem));
  }
  22%,
  68% {
    opacity: 1;
    transform: translate(-50%, -50%);
  }
  100% {
    opacity: 0;
    transform: translate(-50%, calc(-50% - 0.5rem));
  }
}

@keyframes reveal {
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes signature-reveal {
  to {
    opacity: 1;
    transform: translate(-50%, 0);
  }
}

@keyframes soft-reveal {
  to {
    opacity: 1;
  }
}

@media (max-width: 540px) {
  .divider {
    height: clamp(10rem, 31vh, 15rem);
  }

  .word-pair {
    width: min(78vw, 20rem);
    gap: clamp(3.5rem, 20vw, 6rem);
    font-size: clamp(1.9rem, 10vw, 2.6rem);
  }

  .word-pair--en {
    width: min(84vw, 22rem);
    gap: clamp(2.6rem, 15vw, 4.5rem);
    font-size: clamp(0.78rem, 4vw, 1rem);
    letter-spacing: 0.14em;
  }

  h1 {
    font-size: clamp(3.05rem, 16vw, 4.8rem);
    letter-spacing: 0.12em;
    text-indent: 0.12em;
  }

  .english-name {
    font-size: 0.67rem;
    letter-spacing: 0.2em;
  }

  .identity__core--en h1 {
    font-size: clamp(2.35rem, 12vw, 4rem);
    letter-spacing: 0.02em;
  }

  .signature {
    top: 74%;
  }
}

@media (max-height: 620px) {
  .divider {
    height: 12rem;
  }

  .signature {
    top: 76%;
  }

  footer {
    display: none;
  }
}

@media (prefers-reduced-motion: reduce) {
  .animations-running .divider {
    opacity: 1;
    transform: translate(-50%, -50%) scaleY(1);
    animation: none;
  }

  .animations-running .word-pair {
    display: none;
    animation: none;
  }

  .animations-running .identity__core,
  .animations-running .signature,
  .animations-running footer {
    opacity: 1;
    transform: translate(-50%, 0);
    animation: none;
  }

  .animations-running .identity__core,
  .animations-running footer {
    transform: none;
  }
}