## :empty 选择器
### 定义和用法
:empty选择器选择每个没有任何子级的元素，包括文本节点。
* * *
## 实例--指定空的p元素的背景色：
```
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>W3Cschool教程(w3cschool.cn)</title>
<style>
p:empty
{
width:100px;
height:20px;
background:#ff0000;
}
</style>
</head>
<body>
<p></p>
<p>A paragraph.</p>
<p>Another paragraph.</p>
</body>
</html>
```
- CSS常用样式控制
- background--背景
- Text--文本
- CSS属性
- align-*
- animation-*
- appearance
- backface-visibility
- background
- background-attachment
- background-blend-mode
- background-clip
- background-color
- background-image
- background-origin
- background-position
- background-repeat
- background-size
- border
- border-bottom
- border-bottom-color
- border-bottom-left-radius
- border-bottom-right-radius
- border-bottom-style
- border-bottom-width
- border-collapse
- border-color
- border-image
- border-image-outset
- border-image-repeat
- border-image-source
- border-image-width
- Border-left
- border-left-color
- border-left-style
- border-left-width
- border-image-slice
- border-radius
- border-right
- border-right-color
- border-right-style
- border-right-width
- border-spacing
- border-style
- border-top
- border-top-color
- border-top-left-radius
- border-top-right-radius
- border-top-style
- border-top-width
- border-width
- bottom
- box-shadow
- box-sizing
- caption-side
- clear
- clip
- color
- column-count
- column-gap
- column-rule
- column-rule-color
- column-rule-style
- column-rule-width
- column-span
- column-width
- columns
- content
- counter-increment
- counter-reset
- cursor
- direction
- display
- Empty-cells
- filter(滤镜)
- CSS 伪元素选择器
- :active 选择器
- :after 选择器
- :before 选择器
- :checked 选择器
- :disabled 选择器
- :empty 选择器
- :enabled 选择器
- :first-child 伪元素
- :first-letter 伪元素
- :first-line 伪元素
- :first-of-type 选择器
- :focus 选择器
- :hover 选择器