footer {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 10px;
  color: var(--text-sub);
  padding: 8px 12px;
  flex-shrink: 0;
}

/* 将快捷键按钮定位到页脚左侧，与文案同行 */
footer #shortcut-toggle-btn {
  position: absolute;
  left: 12px;
  top: 50%;
  transform: translateY(-50%);
  z-index: 3;
}

/* 右侧显示支持的音乐来源文案 */
.footer-sources {
  position: absolute;
  right: 12px;
  top: 50%;
  transform: translateY(-50%);
  font-size: 11px;
  color: var(--text-sub);
  white-space: nowrap;
}