/* ===== 四首歌曲主题 =====
   每首歌通过 <body data-theme="..."> 切换配色与氛围 */

/* ---------- 菜单 · 星云霓虹 ---------- */
body[data-theme="menu"] {
  --accent: #7df9ff;
  --accent2: #a78bfa;
  --glow: rgba(125, 249, 255, .5);
  --bg0: #140a28;
  --bg1: #2a1550;
  /* 修复：background 简写会重置 background-color 为 transparent，
   * 高度错位时露出浏览器默认白色画布（白色顶栏）；改为显式底色 + 渐变图 */
  background-color: #0d061e;
  background-image: radial-gradient(120% 100% at 50% 0%, #1c1038 0%, #0d061e 55%, #050210 100%);
}

/* ---------- 卡农 · 古典鎏金 ---------- */
body[data-theme="canon"] {
  --accent: #ffd76a;
  --accent2: #ff9a3c;
  --glow: rgba(255, 196, 92, .65);
  --bg0: #170b2b;
  --bg1: #3a1a45;
  background-color: #170b2b;
  background-image: radial-gradient(120% 100% at 50% 0%, #2c1240 0%, #170b2b 55%, #0c0616 100%);
}
body[data-theme="canon"] .song-card { --card-a: #4a2352; --card-b: #1c0e30; --card-deco: "♬"; color: #ffd76a; }

/* ---------- 大鱼 · 深海幽蓝 ---------- */
body[data-theme="fish"] {
  --accent: #5ad1ff;
  --accent2: #8f7bff;
  --glow: rgba(90, 209, 255, .7);
  --bg0: #04121f;
  --bg1: #0b2b44;
  background-color: #041522;
  background-image: radial-gradient(120% 100% at 50% 0%, #082a44 0%, #041522 55%, #020a12 100%);
}
body[data-theme="fish"] .song-card { --card-a: #0e3d5c; --card-b: #041826; --card-deco: "🐋"; color: #5ad1ff; }

/* ---------- 起风了 · 晴空流云 ---------- */
body[data-theme="wind"] {
  --accent: #7ee8fa;
  --accent2: #a8ffd9;
  --glow: rgba(126, 232, 250, .7);
  --bg0: #071828;
  --bg1: #0d3550;
  background-color: #071a2c;
  background-image: radial-gradient(120% 100% at 50% 0%, #0d3350 0%, #071a2c 55%, #040d18 100%);
}
body[data-theme="wind"] .song-card { --card-a: #10455f; --card-b: #061a2c; --card-deco: "☁"; color: #7ee8fa; }

/* ---------- 青花瓷 · 青花水墨 ---------- */
body[data-theme="china"] {
  --accent: #6fc3ff;
  --accent2: #c9e8ff;
  --glow: rgba(111, 195, 255, .65);
  --bg0: #07101e;
  --bg1: #11304c;
  background-color: #081423;
  background-image: radial-gradient(120% 100% at 50% 0%, #0f2a48 0%, #081423 55%, #040a14 100%);
}
body[data-theme="china"] .song-card { --card-a: #12415f; --card-b: #071222; --card-deco: "❀"; color: #6fc3ff; }

/* 游戏内轨道发光配色跟随主题 */
body[data-theme="canon"]  #game { --lane-glow: rgba(255, 196, 92, .35); }
body[data-theme="fish"]   #game { --lane-glow: rgba(90, 209, 255, .3); }
body[data-theme="wind"]   #game { --lane-glow: rgba(126, 232, 250, .3); }
body[data-theme="china"]  #game { --lane-glow: rgba(111, 195, 255, .3); }