/* ===== Z3 全局坐标归零 ===== */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html, body {
  width: 100%;
  height: 100%;
  overflow: hidden;
}

/* ===== Z3 顶部菜单栏（自适应） ===== */
#global-topbar {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: clamp(8px, 4vw, 40px);          /* 高度随屏幕缩放，但保持最小 44px */
  background: rgba(10, 10, 20, 0);
  color: #eee;
  z-index: 3;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 clamp(10px, 2vw, 20px);       /* 水平内边距自适应 */
  box-shadow: 0 1px 8px rgba(0,0,0,0);
  font-family: 'Segoe UI', 'PingFang SC', sans-serif;
  user-select: none;
}

.topbar-logo {
  font-weight: 600;
  font-size: clamp(13px, 1.5vw, 16px);     /* 文字大小自适应 */
  letter-spacing: 0.3px;
}

.topbar-nav {
  display: flex;
  gap: clamp(6px, 1.5vw, 12px);            /* 按钮间距自适应 */
  align-items: center;
}

.topbar-nav button {
  background: rgba(255,255,255,0.08);
  border: 1px solid rgba(255,255,255,0.15);
  color: #ddd;
  padding: clamp(4px, 0.8vw, 6px) clamp(12px, 2vw, 16px); /* 按钮内边距自适应 */
  border-radius: 6px;
  font-size: clamp(11px, 1.2vw, 14px);     /* 按钮文字自适应 */
  cursor: pointer;
  transition: all 0.2s;
  white-space: nowrap;
}

.topbar-nav button:hover {
  background: rgba(255,255,255,0.2);
  border-color: rgba(255,255,255,0.35);
  color: #fff;
}

#btn-music {
  font-size: clamp(14px, 2.5vw, 18px);
  padding: clamp(4px, 0.5vw, 6px) clamp(8px, 1vw, 10px);
  line-height: 1;
}