/* ========== 品牌开场动画 - Constellation on Black Velvet ========== */
/* 简化版 - 粒子汇聚效果 */

/* --- Overlay 基础 --- */
.intro-overlay {
  position: fixed;
  inset: 0;
  z-index: 9999;
  background: #000000;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: opacity 0.5s ease;
}

/* --- 内容容器 --- */
.intro-content {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
}

/* --- 品牌名容器 --- */
.intro-brand {
  position: relative;
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 24px;
}

/* 左半 "SIP" */
.intro-brand__left,
.intro-brand__right {
  font-size: clamp(48px, 8vw, 96px);
  font-weight: 400;
  letter-spacing: 8px;
  color: #ffffff;
  white-space: nowrap;
  opacity: 0;
  animation: intro-fade-in 1s ease forwards;
}

.intro-brand__left {
  animation-delay: 0.2s;
}

.intro-brand__right {
  animation-delay: 0.4s;
}

/* --- 分隔符 × --- */
.intro-sep {
  font-size: clamp(24px, 3vw, 40px);
  font-weight: 200;
  color: #9a9a9a;
  opacity: 0;
  animation: intro-fade-in 1s ease 0.6s forwards;
}

/* --- 副标题 "逆熵智行" --- */
.intro-subtitle {
  font-size: clamp(14px, 2vw, 22px);
  font-weight: 600;
  letter-spacing: 6px;
  color: #bdbdbd;
  margin-bottom: 12px;
  opacity: 0;
  animation: intro-fade-in 1s ease 0.8s forwards;
}

/* --- Tagline --- */
.intro-tagline {
  font-size: clamp(11px, 1.2vw, 14px);
  font-weight: 200;
  letter-spacing: 2px;
  color: #9a9a9a;
  opacity: 0;
  animation: intro-fade-in 1s ease 1s forwards;
}

/* --- 底部装饰线 --- */
.intro-line {
  position: absolute;
  bottom: 25%;
  left: 50%;
  transform: translateX(-50%);
  height: 1px;
  width: 0;
  background: linear-gradient(
    90deg,
    transparent,
    #ffb829 20%,
    #ffffff 50%,
    #8052ff 80%,
    transparent
  );
  animation: intro-line-expand 2s ease 1.2s forwards;
}

/* --- 跳过按钮 --- */
.intro-skip {
  position: absolute;
  bottom: 48px;
  right: 48px;
  font-size: 12px;
  color: #9a9a9a;
  cursor: pointer;
  letter-spacing: 1px;
  text-transform: uppercase;
  transition: color 0.2s ease;
  z-index: 10000;
  border: none;
  background: none;
  font-family: inherit;
}

.intro-skip:hover {
  color: #ffffff;
}

/* ==========================================================
   KEYFRAMES
   ========================================================== */

@keyframes intro-fade-in {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes intro-line-expand {
  from {
    width: 0;
    opacity: 0;
  }
  to {
    width: 50vw;
    opacity: 0.6;
  }
}

/* --- 减少动画偏好 --- */
@media (prefers-reduced-motion: reduce) {
  .intro-overlay,
  .intro-brand__left,
  .intro-brand__right,
  .intro-sep,
  .intro-subtitle,
  .intro-tagline,
  .intro-line {
    animation: none !important;
  }
  
  .intro-overlay {
    display: none;
  }
  
  body {
    opacity: 1 !important;
  }
}