使用了 polyfill 以后 `:focus` 样式在鼠标、键盘激活时均会展现，而使用了 `.focus-visible` 样式仅在通过键盘激活时展现。 :::warning 本例非 DLS 样式，仅作为示例。需注意对 `:focus-visible` 的处理在 Firefox 和 Safari 下无效，目前在这两个浏览器下点击不会使按钮处于 `:focus` 状态。 ::: After including the polyfill, `:focus` styles are applied both with mouse clicks and keyboard activation, while `.focus-visible` styles are only applied with keyboard activation. :::warning This example is only for demonstration purpose and doesn't reflect DLS's styles. Please note that our polyfill for `:focus-visible` works differently in Firefox and Safari. Clicking a button in these browsers won't set the `:focus` state on the button. :::