css - 为什么我不能在伪元素中使用伪元素？

Question

我们可以像这样使用伪元素:

div:before{
    content: "pseudo!";
    position: absolute;
    right: 200px;
}

但是对于那个伪元素，我想像这样装饰第一个字母:

div:before:first-letter{
    font-size: 26px;
    color: red;
}

但是这不再有效了。为什么？

Answer 1

因为 the spec每个选择器只允许一个伪元素:

Only one pseudo-element may appear per selector, and if present it must appear after the sequence of simple selectors that represents the subjects of the selector. Note: A future version of this specification may allow multiple pseudo-elements per selector.