/* 开场：星野 + 标题（定格页） */
@import url('https://fonts.googleapis.com/css2?family=Noto+Sans+SC:wght@300;700;900&display=swap');

.intro-splash {
  position: fixed;
  inset: 0;
  z-index: 9999;
  background: #020617;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  cursor: pointer;
  transition: opacity 0.9s ease, visibility 0.9s, transform 0.9s;
}
.intro-splash.leaving {
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  transform: scale(1.03);
}

.vortex-canvas {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  z-index: 1;
  pointer-events: none;
}

/* 外层：只做缓慢浮动 */
.intro-content {
  position: relative;
  z-index: 10;
  text-align: center;
  pointer-events: none;
  will-change: transform;
  backface-visibility: hidden;
  transform: translate3d(0, 0, 0);
  animation: content-float 9s linear 1.15s infinite;
}
/* 内层：入场（上浮 + 淡入），与浮动 transform 分离才不卡顿 */
.intro-content-inner {
  will-change: transform, opacity;
  backface-visibility: hidden;
  animation: intro-content-in 1.1s cubic-bezier(0.22, 1, 0.36, 1) forwards;
}
@keyframes intro-content-in {
  from {
    opacity: 0;
    transform: translate3d(0, 28px, 0);
  }
  to {
    opacity: 1;
    transform: translate3d(0, 0, 0);
  }
}
/* 多关键帧 + linear ≈ 正弦波，上下更顺滑 */
@keyframes content-float {
  0%   { transform: translate3d(0, 0, 0); }
  12.5% { transform: translate3d(0, -2px, 0); }
  25%  { transform: translate3d(0, -5px, 0); }
  37.5% { transform: translate3d(0, -7px, 0); }
  50%  { transform: translate3d(0, -8px, 0); }
  62.5% { transform: translate3d(0, -7px, 0); }
  75%  { transform: translate3d(0, -5px, 0); }
  87.5% { transform: translate3d(0, -2px, 0); }
  100% { transform: translate3d(0, 0, 0); }
}

.glow-title {
  position: relative;
  margin: 0;
  font-family: 'Noto Sans SC', sans-serif;
  font-size: clamp(44px, 10vw, 80px);
  font-weight: 900;
  letter-spacing: 0.28em;
  padding-left: 0.28em;
  display: flex;
  justify-content: center;
  gap: 0.02em;
}
.glow-title::after {
  content: '';
  position: absolute;
  left: 50%;
  bottom: -12px;
  transform: translateX(-50%);
  width: 72%;
  height: 2px;
  background: linear-gradient(90deg, transparent, rgba(251, 191, 36, 0.42), rgba(129, 140, 248, 0.38), transparent);
  opacity: 0.72;
}

.glow-char {
  display: inline-block;
  color: #fffbeb;
  text-shadow:
    0 0 12px rgba(255, 251, 235, 0.48),
    0 0 24px rgba(251, 191, 36, 0.34),
    0 0 36px rgba(129, 140, 248, 0.22);
}

.intro-tagline {
  margin: 28px 0 0;
  font-family: 'Noto Sans SC', sans-serif;
  font-size: clamp(13px, 2.5vw, 15px);
  font-weight: 300;
  color: rgba(203, 213, 225, 0.88);
  letter-spacing: 0.32em;
  padding-left: 0.32em;
}
.intro-badge {
  display: inline-block;
  margin-top: 14px;
  padding: 5px 14px;
  font-size: 11px;
  letter-spacing: 0.22em;
  color: rgba(254, 243, 199, 0.95);
  border: 1px solid rgba(251, 191, 36, 0.38);
  border-radius: 999px;
  background: rgba(15, 23, 42, 0.55);
}
.intro-enter-hint {
  margin-top: 48px;
  font-size: 12px;
  letter-spacing: 0.28em;
  color: rgba(148, 163, 184, 0.82);
}
.intro-enter-hint .arrow {
  display: inline-block;
  margin-left: 6px;
  will-change: transform;
  animation: arrow-nudge 2.8s linear infinite;
}
@keyframes arrow-nudge {
  0%, 100% { transform: translate3d(0, 0, 0); opacity: 0.78; }
  50% { transform: translate3d(0, 4px, 0); opacity: 1; }
}

body.intro-active .site-nav,
body.intro-active .main,
body.intro-active .site-footer {
  visibility: hidden;
}

@media (prefers-reduced-motion: reduce) {
  .intro-content,
  .intro-content-inner {
    animation: none;
    opacity: 1;
    transform: none;
  }
}