/* ==========================================================
   intro.css —— 开场「点击开始」层
   这一层的点击同时承担解锁浏览器音频播放的职责
   ========================================================== */

#start-layer {
  position: fixed; inset: 0;
  z-index: 60;
  display: flex; flex-direction: column;
  align-items: center; justify-content: center;
  text-align: center;
  cursor: pointer;
  opacity: 0; pointer-events: none;
  transition: opacity 0.9s ease;
  background: radial-gradient(ellipse 60% 50% at 50% 50%, rgba(10, 8, 26, 0.55) 0%, transparent 70%);
  -webkit-tap-highlight-color: transparent;
}
#start-layer.show { opacity: 1; pointer-events: auto; }
#start-layer.hide { opacity: 0; pointer-events: none; }

/* 点击后：标题先退一步，按钮区域整体淡出 */
#start-layer.hide #intro-title { opacity: 0; transform: translateY(-28px) scale(0.96); }
#start-layer.hide .start-btn,
#start-layer.hide .start-tip { opacity: 0; transition: opacity 0.35s ease; }

/* ===== 标题 ===== */
#intro-title { transition: opacity 0.8s ease, transform 0.8s ease; }
#intro-title h1 {
  font-family: 'Noto Serif SC', serif;
  font-size: clamp(26px, 7vmin, 44px);
  font-weight: 700;
  letter-spacing: 4px;
  background: linear-gradient(135deg, #e9d5ff 0%, #c4b5fd 40%, #93c5fd 100%);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  margin-bottom: 14px;
}
#intro-title p {
  font-size: clamp(12px, 3.2vmin, 15px);
  color: rgba(196, 181, 253, 0.55);
  letter-spacing: 6px;
}

/* ===== 开始按钮：呼吸光环 ===== */
.start-btn {
  margin-top: 46px;
  display: inline-flex; align-items: center; gap: 10px;
  padding: 13px 30px;
  border-radius: 999px;
  border: 1px solid rgba(196, 181, 253, 0.35);
  background: rgba(139, 92, 246, 0.1);
  color: #e9d5ff;
  font-family: 'Noto Sans SC', sans-serif;
  font-size: 15px; letter-spacing: 3px;
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
  position: relative;
  animation: startBreath 2.8s ease-in-out infinite;
  transition: background 0.3s, border-color 0.3s, transform 0.2s;
}
.start-btn svg { width: 17px; height: 17px; flex: none; }
#start-layer:hover .start-btn {
  background: rgba(139, 92, 246, 0.2);
  border-color: rgba(196, 181, 253, 0.6);
}
#start-layer:active .start-btn { transform: scale(0.96); }
@keyframes startBreath {
  0%, 100% { box-shadow: 0 0 0 0 rgba(167, 139, 250, 0.28), 0 0 22px rgba(139, 92, 246, 0.15); }
  50%      { box-shadow: 0 0 0 14px rgba(167, 139, 250, 0), 0 0 34px rgba(139, 92, 246, 0.3); }
}

.start-tip {
  margin-top: 20px;
  font-size: 12px;
  color: rgba(196, 181, 253, 0.38);
  letter-spacing: 2px;
}