空的子元素或content

Comments, processing instructions, and CSS content do not affect whether an element is considered empty.

2025-04-12

Written by: tdtc

w3schools Example

<style>
.box {
  background-color: lightgreen;
  height: 90px;
  width: 90px;
}

.box:empty {
  background-color: red;
}
</style>


<h1>Demo of :empty</h1>

<div class="box"></div><br>
<div class="box">I will be lightgreen.</div><br>
<div class="box"><!-- I will be salmon --></div><br>
<div class="box"> <!-- I will be lightgreen --> </div>

Ref