/* ============================================
   Android 16 / Material Design 3 风格样式
   ============================================ */

/* === CSS 变量 - Material You 色彩系统 === */
:root {
  /* 主色调 - Android 16 风格动态色彩 */
  --md-primary: #6750A4;
  --md-on-primary: #FFFFFF;
  --md-primary-container: #EADDFF;
  --md-on-primary-container: #21005E;

  /* 次要色 */
  --md-secondary: #625B71;
  --md-on-secondary: #FFFFFF;
  --md-secondary-container: #E8DEF8;
  --md-on-secondary-container: #1E192B;

  /* 第三色 */
  --md-tertiary: #7D5260;
  --md-on-tertiary: #FFFFFF;
  --md-tertiary-container: #FFD8E4;
  --md-on-tertiary-container: #370B1D;

  /* 错误色 */
  --md-error: #B3261E;
  --md-on-error: #FFFFFF;
  --md-error-container: #F9DEDC;
  --md-on-error-container: #410E0B;

  /* 表面色 */
  --md-surface: #FEF7FF;
  --md-on-surface: #1C1B1F;
  --md-surface-variant: #E7E0EC;
  --md-on-surface-variant: #49454E;
  --md-surface-container-low: #F7F2FA;
  --md-surface-container: #F3EDF7;
  --md-surface-container-high: #ECE6F0;
  --md-surface-container-highest: #E6E0E9;

  /* 轮廓 */
  --md-outline: #79747E;
  --md-outline-variant: #CAC4D0;

  /* 背景 */
  --md-background: #FEF7FF;
  --md-on-background: #1C1B1F;

  /* 阴影 */
  --md-elevation-1: 0 1px 3px 0 rgba(0,0,0,0.12), 0 1px 2px 0 rgba(0,0,0,0.08);
  --md-elevation-2: 0 3px 6px 0 rgba(0,0,0,0.12), 0 2px 4px 0 rgba(0,0,0,0.08);
  --md-elevation-3: 0 8px 12px 0 rgba(0,0,0,0.12), 0 4px 8px 0 rgba(0,0,0,0.08);
  --md-elevation-4: 0 12px 24px 0 rgba(0,0,0,0.14), 0 6px 12px 0 rgba(0,0,0,0.10);

  /* 圆角 */
  --md-radius-xs: 4px;
  --md-radius-sm: 8px;
  --md-radius-md: 12px;
  --md-radius-lg: 16px;
  --md-radius-xl: 24px;
  --md-radius-2xl: 28px;
  --md-radius-full: 9999px;

  /* 字体 */
  --md-font-family: 'Roboto', 'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', sans-serif;

  /* 字体大小 */
  --md-font-display-lg: 57px;
  --md-font-display-md: 45px;
  --md-font-display-sm: 36px;
  --md-font-headline-lg: 32px;
  --md-font-headline-md: 28px;
  --md-font-headline-sm: 24px;
  --md-font-title-lg: 22px;
  --md-font-title-md: 16px;
  --md-font-title-sm: 14px;
  --md-font-body-lg: 16px;
  --md-font-body-md: 14px;
  --md-font-body-sm: 12px;
  --md-font-label-lg: 14px;
  --md-font-label-md: 12px;
  --md-font-label-sm: 11px;

  /* 间距 */
  --md-spacing-xs: 4px;
  --md-spacing-sm: 8px;
  --md-spacing-md: 16px;
  --md-spacing-lg: 24px;
  --md-spacing-xl: 32px;
  --md-spacing-2xl: 48px;

  /* 过渡 */
  --md-transition-standard: 200ms cubic-bezier(0.2, 0.0, 0, 1.0);
  --md-transition-emphasized: 400ms cubic-bezier(0.2, 0.0, 0, 1.0);

  /* 状态栏高度 */
  --status-bar-height: 28px;
  --nav-bar-height: 56px;
}

/* === 深色主题 === */
[data-theme="dark"] {
  --md-primary: #D0BCFF;
  --md-on-primary: #381E72;
  --md-primary-container: #4F378B;
  --md-on-primary-container: #EADDFF;

  --md-secondary: #CCC2DC;
  --md-on-secondary: #332D41;
  --md-secondary-container: #4A4458;
  --md-on-secondary-container: #E8DEF8;

  --md-tertiary: #EFB8C8;
  --md-on-tertiary: #492532;
  --md-tertiary-container: #633B48;
  --md-on-tertiary-container: #FFD8E4;

  --md-error: #F2B8B5;
  --md-on-error: #601410;
  --md-error-container: #8C1D18;
  --md-on-error-container: #F9DEDC;

  --md-surface: #1C1B1F;
  --md-on-surface: #E6E1E5;
  --md-surface-variant: #49454F;
  --md-on-surface-variant: #CAC4D0;
  --md-surface-container-low: #1C1B1F;
  --md-surface-container: #201F24;
  --md-surface-container-high: #2B2930;
  --md-surface-container-highest: #36343B;

  --md-outline: #938F99;
  --md-outline-variant: #49454F;

  --md-background: #1C1B1F;
  --md-on-background: #E6E1E5;
}

/* === 全局重置 === */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html, body {
  height: 100%;
  width: 100%;
  overflow: hidden;
  font-family: var(--md-font-family);
  background: var(--md-surface);
  color: var(--md-on-surface);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* === Android 设备框架 === */
.android-device {
  width: 100%;
  max-width: 420px;
  margin: 0 auto;
  height: 100vh;
  display: flex;
  flex-direction: column;
  background: var(--md-surface);
  position: relative;
  overflow: hidden;
}

/* === 状态栏 === */
.status-bar {
  height: 28px;
  padding: 0 16px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: var(--md-surface-container);
  font-size: var(--md-font-label-sm);
  font-weight: 500;
  color: var(--md-on-surface);
  flex-shrink: 0;
}

.status-bar-left {
  display: flex;
  align-items: center;
  gap: 6px;
}

.status-bar-right {
  display: flex;
  align-items: center;
  gap: 6px;
}

.status-bar-icon {
  font-size: 12px;
  opacity: 0.8;
}

.status-bar-time {
  font-weight: 600;
}

/* === 顶部应用栏 === */
.top-app-bar {
  height: 56px;
  padding: 0 4px 0 16px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: var(--md-surface-container);
  flex-shrink: 0;
  border-bottom: 1px solid var(--md-outline-variant);
}

.top-app-bar-title {
  font-size: var(--md-font-title-lg);
  font-weight: 500;
  color: var(--md-on-surface);
  letter-spacing: 0;
}

.top-app-bar-actions {
  display: flex;
  align-items: center;
  gap: 4px;
}

/* === 图标按钮 === */
.icon-button {
  width: 40px;
  height: 40px;
  border-radius: var(--md-radius-full);
  border: none;
  background: transparent;
  color: var(--md-on-surface-variant);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background var(--md-transition-standard);
  position: relative;
  overflow: hidden;
  font-size: 20px;
}

.icon-button:hover {
  background: rgba(103, 80, 164, 0.08);
}

.icon-button:active {
  background: rgba(103, 80, 164, 0.12);
}

/* === 主内容区域 === */
.main-content {
  flex: 1;
  overflow-y: auto;
  overflow-x: hidden;
  padding: var(--md-spacing-md);
  -webkit-overflow-scrolling: touch;
}

.main-content::-webkit-scrollbar {
  width: 4px;
}

.main-content::-webkit-scrollbar-thumb {
  background: var(--md-outline-variant);
  border-radius: 2px;
}

/* === 卡片 === */
.md-card {
  background: var(--md-surface-container-low);
  border-radius: var(--md-radius-md);
  padding: var(--md-spacing-lg);
  box-shadow: var(--md-elevation-1);
  border: 1px solid var(--md-outline-variant);
  transition: box-shadow var(--md-transition-standard);
}

.md-card:hover {
  box-shadow: var(--md-elevation-2);
}

.md-card-elevated {
  background: var(--md-surface-container-low);
  border-radius: var(--md-radius-lg);
  padding: var(--md-spacing-md);
  box-shadow: var(--md-elevation-2);
  border: none;
}

/* === 文本输入框 (Material Design 3 Outlined TextField) === */
.md-text-field {
  position: relative;
  margin-bottom: var(--md-spacing-lg);
  width: 100%;
}

.md-text-field input {
  width: 100%;
  height: 56px;
  padding: 24px 16px 8px 16px;
  border: 1px solid var(--md-outline);
  border-radius: var(--md-radius-xs) var(--md-radius-xs) 0 0;
  background: transparent;
  font-size: var(--md-font-body-lg);
  color: var(--md-on-surface);
  font-family: var(--md-font-family);
  outline: none;
  transition: border-color var(--md-transition-standard),
              box-shadow var(--md-transition-standard);
}

.md-text-field input:focus {
  border-color: var(--md-primary);
  border-width: 2px;
  padding: 23px 15px 7px 15px;
  box-shadow: none;
}

.md-text-field label {
  position: absolute;
  left: 16px;
  top: 50%;
  transform: translateY(-50%);
  font-size: var(--md-font-body-lg);
  color: var(--md-on-surface-variant);
  transition: all var(--md-transition-standard);
  pointer-events: none;
  background: transparent;
}

.md-text-field input:focus + label,
.md-text-field input:not(:placeholder-shown) + label {
  top: 8px;
  transform: translateY(0);
  font-size: var(--md-font-label-sm);
  color: var(--md-primary);
}

.md-text-field input:not(:focus):not(:placeholder-shown) + label {
  color: var(--md-on-surface-variant);
}

.md-text-field .supporting-text {
  font-size: var(--md-font-label-sm);
  color: var(--md-on-surface-variant);
  margin-top: var(--md-spacing-xs);
  padding-left: var(--md-spacing-md);
}

.md-text-field .supporting-text.error {
  color: var(--md-error);
}

.md-text-field.error input {
  border-color: var(--md-error);
}

/* === 按钮 === */
.md-button {
  height: 40px;
  padding: 0 24px;
  border-radius: var(--md-radius-full);
  font-size: var(--md-font-label-lg);
  font-weight: 500;
  font-family: var(--md-font-family);
  border: none;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  letter-spacing: 0.1px;
  transition: all var(--md-transition-standard);
  white-space: nowrap;
  position: relative;
  overflow: hidden;
}

/* 填充按钮 */
.md-button-filled {
  background: var(--md-primary);
  color: var(--md-on-primary);
  box-shadow: var(--md-elevation-1);
}

.md-button-filled:hover {
  background: #5C469C;
  box-shadow: var(--md-elevation-2);
}

.md-button-filled:active {
  background: #4A368B;
  box-shadow: var(--md-elevation-1);
}

.md-button-filled:disabled {
  background: rgba(29, 27, 32, 0.12);
  color: rgba(29, 27, 32, 0.38);
  box-shadow: none;
  cursor: not-allowed;
}

/* 填充色调按钮 */
.md-button-filled-tonal {
  background: var(--md-secondary-container);
  color: var(--md-on-secondary-container);
}

.md-button-filled-tonal:hover {
  background: #D8CEE8;
}

.md-button-filled-tonal:active {
  background: #C8BED8;
}

/* 轮廓按钮 */
.md-button-outlined {
  background: transparent;
  color: var(--md-primary);
  border: 1px solid var(--md-outline);
}

.md-button-outlined:hover {
  background: rgba(103, 80, 164, 0.08);
  border-color: var(--md-primary);
}

.md-button-outlined:active {
  background: rgba(103, 80, 164, 0.12);
}

/* 文本按钮 */
.md-button-text {
  background: transparent;
  color: var(--md-primary);
  padding: 0 12px;
}

.md-button-text:hover {
  background: rgba(103, 80, 164, 0.08);
}

/* 大型 FAB */
.md-fab {
  width: 56px;
  height: 56px;
  border-radius: var(--md-radius-lg);
  background: var(--md-primary-container);
  color: var(--md-on-primary-container);
  border: none;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--md-elevation-3);
  transition: all var(--md-transition-standard);
  font-size: 24px;
}

.md-fab:hover {
  box-shadow: var(--md-elevation-4);
}

.md-fab:active {
  box-shadow: var(--md-elevation-2);
}

.md-fab-extended {
  width: auto;
  height: 56px;
  padding: 0 24px;
  border-radius: var(--md-radius-lg);
  gap: 12px;
  font-size: var(--md-font-label-lg);
  font-weight: 500;
  font-family: var(--md-font-family);
}

.md-fab-primary {
  background: var(--md-primary);
  color: var(--md-on-primary);
}

/* === 芯片 === */
.md-chip {
  height: 32px;
  padding: 0 16px;
  border-radius: var(--md-radius-sm);
  background: var(--md-surface-variant);
  color: var(--md-on-surface-variant);
  border: 1px solid var(--md-outline-variant);
  font-size: var(--md-font-label-lg);
  font-family: var(--md-font-family);
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  transition: all var(--md-transition-standard);
}

.md-chip:hover {
  background: var(--md-surface-container-high);
}

.md-chip.active {
  background: var(--md-secondary-container);
  color: var(--md-on-secondary-container);
  border-color: var(--md-secondary);
}

/* === 徽章 === */
.md-badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 16px;
  height: 16px;
  padding: 0 4px;
  border-radius: var(--md-radius-full);
  background: var(--md-error);
  color: var(--md-on-error);
  font-size: 10px;
  font-weight: 600;
}

/* === 分隔线 === */
.md-divider {
  height: 1px;
  background: var(--md-outline-variant);
  margin: var(--md-spacing-md) 0;
}

.md-divider-thick {
  height: 8px;
  background: var(--md-surface-container);
  margin: 0 -16px;
}

/* === 视频容器 === */
.video-container {
  width: 100%;
  background: #000;
  border-radius: var(--md-radius-lg);
  overflow: hidden;
  position: relative;
  aspect-ratio: 16 / 9;
}

.video-container video {
  width: 100%;
  height: 100%;
  object-fit: contain;
}

.video-container .no-stream {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  color: rgba(255, 255, 255, 0.6);
  gap: var(--md-spacing-md);
}

.video-container .no-stream .icon {
  font-size: 48px;
  opacity: 0.5;
}

.video-container .no-stream .text {
  font-size: var(--md-font-title-sm);
  font-weight: 400;
}

/* === 会话代码区域 === */
.session-code-display {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--md-spacing-md);
  padding: var(--md-spacing-md);
  background: var(--md-primary-container);
  border-radius: var(--md-radius-md);
  margin: var(--md-spacing-md) 0;
}

.session-code-text {
  font-size: 28px;
  font-weight: 700;
  letter-spacing: 6px;
  color: var(--md-on-primary-container);
  font-family: 'Roboto Mono', monospace;
}

.session-code-actions {
  display: flex;
  gap: 4px;
}

/* === 底部导航栏 === */
.bottom-nav {
  height: 56px;
  background: var(--md-surface-container);
  display: flex;
  align-items: center;
  justify-content: space-around;
  border-top: 1px solid var(--md-outline-variant);
  flex-shrink: 0;
  padding-bottom: env(safe-area-inset-bottom, 0);
}

.nav-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 2px;
  padding: 0 12px;
  cursor: pointer;
  position: relative;
  color: var(--md-on-surface-variant);
  transition: color var(--md-transition-standard);
  min-width: 64px;
  text-decoration: none;
}

.nav-item .nav-icon {
  font-size: 20px;
  width: 24px;
  height: 24px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.nav-item .nav-label {
  font-size: var(--md-font-label-sm);
  font-weight: 500;
  letter-spacing: 0.5px;
}

.nav-item.active {
  color: var(--md-primary);
}

.nav-item.active::before {
  content: '';
  position: absolute;
  top: 0;
  left: 12px;
  right: 12px;
  height: 3px;
  background: var(--md-primary);
  border-radius: 0 0 3px 3px;
}

/* === 进度指示器 === */
.md-progress-circular {
  width: 48px;
  height: 48px;
  position: relative;
}

.md-progress-circular svg {
  animation: rotate 2s linear infinite;
}

.md-progress-circular circle {
  fill: none;
  stroke: var(--md-primary);
  stroke-width: 4;
  stroke-linecap: round;
  animation: dash 1.5s ease-in-out infinite;
}

@keyframes rotate {
  100% { transform: rotate(360deg); }
}

@keyframes dash {
  0% { stroke-dasharray: 1, 150; stroke-dashoffset: 0; }
  50% { stroke-dasharray: 90, 150; stroke-dashoffset: -35; }
  100% { stroke-dasharray: 90, 150; stroke-dashoffset: -124; }
}

/* === 线性进度条 === */
.md-progress-linear {
  width: 100%;
  height: 4px;
  background: var(--md-surface-variant);
  border-radius: 2px;
  overflow: hidden;
}

.md-progress-linear .indicator {
  height: 100%;
  background: var(--md-primary);
  border-radius: 2px;
  animation: linear-indeterminate 1.5s ease-in-out infinite;
  width: 30%;
}

@keyframes linear-indeterminate {
  0% { transform: translateX(-100%); }
  100% { transform: translateX(400%); }
}

/* === 提示气泡 (Snackbar) === */
.md-snackbar {
  position: fixed;
  bottom: 16px;
  left: 50%;
  transform: translateX(-50%) translateY(100px);
  background: var(--md-on-surface);
  color: var(--md-surface);
  padding: 14px 16px;
  border-radius: var(--md-radius-xs);
  font-size: var(--md-font-body-md);
  display: flex;
  align-items: center;
  gap: 12px;
  box-shadow: var(--md-elevation-3);
  z-index: 1000;
  transition: transform var(--md-transition-emphasized);
  max-width: 360px;
  white-space: nowrap;
}

.md-snackbar.show {
  transform: translateX(-50%) translateY(0);
}

.md-snackbar .snackbar-action {
  color: var(--md-primary-container);
  font-weight: 600;
  cursor: pointer;
  background: none;
  border: none;
  font-size: var(--md-font-label-lg);
  font-family: var(--md-font-family);
}

/* === 对话框 (Modal Bottom Sheet 风格) === */
.md-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.4);
  z-index: 900;
  opacity: 0;
  visibility: hidden;
  transition: all var(--md-transition-standard);
}

.md-overlay.show {
  opacity: 1;
  visibility: visible;
}

.md-bottom-sheet {
  position: fixed;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%) translateY(100%);
  width: 100%;
  max-width: 420px;
  background: var(--md-surface-container-high);
  border-radius: var(--md-radius-xl) var(--md-radius-xl) 0 0;
  padding: var(--md-spacing-lg);
  z-index: 950;
  transition: transform var(--md-transition-emphasized);
  max-height: 80vh;
  overflow-y: auto;
}

.md-bottom-sheet.show {
  transform: translateX(-50%) translateY(0);
}

.md-bottom-sheet .drag-handle {
  width: 32px;
  height: 4px;
  background: var(--md-on-surface-variant);
  opacity: 0.4;
  border-radius: 2px;
  margin: 0 auto var(--md-spacing-md);
}

/* === 状态指示器 === */
.status-indicator {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: var(--md-font-label-lg);
  font-weight: 500;
}

.status-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  position: relative;
}

.status-dot.live {
  background: #34A853;
}

.status-dot.live::after {
  content: '';
  position: absolute;
  inset: -3px;
  border-radius: 50%;
  background: rgba(52, 168, 83, 0.3);
  animation: pulse 2s ease-in-out infinite;
}

.status-dot.offline {
  background: var(--md-outline);
}

@keyframes pulse {
  0%, 100% { transform: scale(1); opacity: 1; }
  50% { transform: scale(1.8); opacity: 0; }
}

/* === 列表项 === */
.md-list-item {
  display: flex;
  align-items: center;
  padding: 12px 16px;
  gap: 16px;
  border-radius: var(--md-radius-md);
  transition: background var(--md-transition-standard);
  cursor: pointer;
}

.md-list-item:hover {
  background: rgba(103, 80, 164, 0.06);
}

.md-list-item .list-icon {
  width: 40px;
  height: 40px;
  border-radius: var(--md-radius-full);
  background: var(--md-secondary-container);
  color: var(--md-on-secondary-container);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 18px;
  flex-shrink: 0;
}

.md-list-item .list-content {
  flex: 1;
  min-width: 0;
}

.md-list-item .list-title {
  font-size: var(--md-font-body-lg);
  font-weight: 400;
  color: var(--md-on-surface);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.md-list-item .list-subtitle {
  font-size: var(--md-font-body-sm);
  color: var(--md-on-surface-variant);
}

/* === 动画 === */
@keyframes slideUp {
  from {
    opacity: 0;
    transform: translateY(24px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes scaleIn {
  from {
    opacity: 0;
    transform: scale(0.9);
  }
  to {
    opacity: 1;
    transform: scale(1);
  }
}

.animate-slide-up {
  animation: slideUp 0.4s var(--md-transition-emphasized) both;
}

.animate-fade-in {
  animation: fadeIn 0.3s var(--md-transition-standard) both;
}

.animate-scale-in {
  animation: scaleIn 0.3s var(--md-transition-emphasized) both;
}

/* === 欢迎/登录区域 === */
.hero-section {
  text-align: center;
  padding: var(--md-spacing-xl) var(--md-spacing-md);
}

.hero-icon {
  width: 80px;
  height: 80px;
  border-radius: var(--md-radius-xl);
  background: var(--md-primary-container);
  color: var(--md-on-primary-container);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 40px;
  margin: 0 auto var(--md-spacing-lg);
  box-shadow: var(--md-elevation-2);
}

.hero-title {
  font-size: var(--md-font-headline-sm);
  font-weight: 500;
  color: var(--md-on-surface);
  margin-bottom: var(--md-spacing-sm);
}

.hero-subtitle {
  font-size: var(--md-font-body-md);
  color: var(--md-on-surface-variant);
  line-height: 1.6;
}

/* === 响应式 === */
@media (min-width: 768px) {
  .android-device {
    max-width: 480px;
    border: 8px solid var(--md-surface-container-high);
    border-radius: 40px;
    height: 90vh;
    margin-top: 5vh;
    box-shadow:
      0 0 0 2px var(--md-outline-variant),
      var(--md-elevation-4);
  }

  body {
    background: #1a1a2e;
    display: flex;
    align-items: center;
    justify-content: center;
  }

  .status-bar {
    border-radius: 32px 32px 0 0;
  }
}

/* === 全屏视频页面样式 === */
.fullscreen-viewer {
  max-width: 100% !important;
  border: none !important;
  border-radius: 0 !important;
  height: 100vh !important;
  margin-top: 0 !important;
}

.fullscreen-viewer .main-content {
  padding: 0;
}

.fullscreen-viewer .video-container {
  border-radius: 0;
  aspect-ratio: auto;
  height: 100%;
}

/* === 连接状态覆盖层 === */
.connection-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.6);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: var(--md-spacing-lg);
  z-index: 800;
  color: white;
}

.connection-overlay .message {
  font-size: var(--md-font-title-md);
  font-weight: 500;
}

/* === 工具提示 === */
[data-tooltip] {
  position: relative;
}

[data-tooltip]::after {
  content: attr(data-tooltip);
  position: absolute;
  bottom: calc(100% + 8px);
  left: 50%;
  transform: translateX(-50%);
  background: var(--md-on-surface);
  color: var(--md-surface);
  padding: 4px 8px;
  border-radius: var(--md-radius-xs);
  font-size: var(--md-font-label-sm);
  white-space: nowrap;
  opacity: 0;
  visibility: hidden;
  transition: all var(--md-transition-standard);
  pointer-events: none;
}

[data-tooltip]:hover::after {
  opacity: 1;
  visibility: visible;
}