body { margin: 0; padding-bottom: 142px; color: #232323; font-family: Arial, "Microsoft YaHei", sans-serif; }
button, input, select { font: inherit; }
button { cursor: pointer; }
button:focus-visible, audio:focus-visible { outline: 3px solid #117947; outline-offset: 4px; }
button:disabled { cursor: default; opacity: .45; }
.course-note { padding: 12px 20px; color: #24553d; background: #edf8f2; text-align: center; font-size: 13px; line-height: 1.6; }
.music-section { padding: 48px 24px 64px; background: #f5f5f5; }
.music-heading { max-width: 1180px; margin: 0 auto 28px; display: flex; align-items: center; justify-content: space-between; gap: 20px; }
.music-heading h2 { margin: 0 0 10px; font-size: 28px; letter-spacing: .12em; }
.music-heading p { margin: 0; color: #666; font-size: 14px; }
#play-all { border: 0; border-radius: 6px; padding: 13px 20px; background: #178a55; color: white; white-space: nowrap; }
#play-all:hover { background: #116d42; }
.track-grid { max-width: 1180px; margin: auto; display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 18px; }
.track { width: 100%; display: flex; align-items: center; gap: 14px; padding: 12px; border: 1px solid #e7e7e7; border-radius: 8px; background: white; color: inherit; text-align: left; transition: border-color .15s, background .15s; }
.track:hover, .track.is-current { border-color: #31c27c; background: #f0faf5; }
.track img { width: 76px; height: 76px; object-fit: cover; border-radius: 4px; flex-shrink: 0; }
.track-copy { display: flex; flex: 1; min-width: 0; flex-direction: column; gap: 8px; line-height: 1.4; }
.track-copy strong { font-size: 14px; overflow-wrap: anywhere; }
.track-copy > span { font-size: 12px; color: #666; overflow-wrap: anywhere; }
.track-indicator { color: #178a55; width: 20px; text-align: center; flex-shrink: 0; }
.player-bar { position: fixed; z-index: 10; bottom: 0; left: 0; right: 0; display: flex; gap: 20px; align-items: center; justify-content: center; padding: 20px 28px; background: rgba(255,255,255,.98); border-top: 1px solid #ddd; box-shadow: 0 -6px 30px #0000000a; }
.now-playing { min-width: 160px; max-width: 320px; flex: 1; display: flex; flex-direction: column; gap: 8px; line-height: 1.4; }
#now-playing { font-size: 14px; overflow-wrap: anywhere; }
#player-status { color: #646464; font-size: 12px; }
.player-buttons { display: flex; gap: 8px; }
.player-buttons button { padding: 10px 12px; border: 1px solid #ccc; border-radius: 5px; background: white; color: #333; white-space: nowrap; }
.player-buttons button:hover:enabled { border-color: #178a55; color: #178a55; }
#player { width: min(450px, 40vw); }
@media (max-width: 1000px) { .track-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
@media (max-width: 650px) {
  body { padding-bottom: 205px; }
  .music-section { padding: 32px 14px; }
  .music-heading { align-items: flex-start; }
  .music-heading h2 { font-size: 24px; }
  .music-heading p { max-width: 200px; line-height: 1.5; }
  .track-grid { grid-template-columns: 1fr; gap: 12px; }
  .player-bar { flex-wrap: wrap; gap: 12px; padding: 14px 16px calc(14px + env(safe-area-inset-bottom)); }
  .now-playing { min-width: 120px; }
  .player-buttons button { padding: 8px; font-size: 12px; }
  #player { width: 100%; }
}