::cue (:cue)

::cue CSS 伪元素匹配所选元素中的WebVTT提示。这可以用于在 VTT 轨道的媒体中使用字幕和其他线索。

只有 CSS 一小部分属性可以与 ::cue 伪元素一起使用：

• color
• opacity
• visibility
• text-decoration and its longhand properties: text-decoration-line, text-decoration-color, and text-decoration-style
• text-shadow
• background and its longhand properties: background-color, background-clip, background-image, background-origin, background-position, background-repeat, background-size, background-attachment, and background-blend-mode
• outline and its longhand properties: outline-color, outline-style, outline-width
• font and its longhand properties: font-kerning, font-style, font-variant, font-variant-numeric, font-variant-position, font-variant-east-asian, font-variant-caps, font-variant-alternates, font-variant-ligatures, font-synthesis, font-feature-settings, font-language-override, font-weight, font-size, font-size-adjust, font-stretch, and font-family
• line-height
• white-space
• text-combine-upright
• ruby-position

属性应用于整个提示集，就像它们是单个单元一样。唯一的例外是背景及其简写属性可以单独应用于每个提示，以避免创建框并遮盖意外大面积的媒体。

::cue | ::cue(<selector>) {
  /* ... */
}

::cue {
  color: #fff;
  background-color: rgba(0, 0, 0, 0.6);
}