CSS指南

边框

样式

border-style指定样式

可选值有

dotted
dashed
solid
double
groove
ridge
inset
none
hidden

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36


<!DOCTYPE html>
<html>
<head>
<style>
p.dotted {border-style: dotted;}
p.dashed {border-style: dashed;}
p.solid {border-style: solid;}
p.double {border-style: double;}
p.groove {border-style: groove;}
p.ridge {border-style: ridge;}
p.inset {border-style: inset;}
p.outset {border-style: outset;}
p.none {border-style: none;}
p.hidden {border-style: hidden;}
p.mix {border-style: dotted dashed solid double;}
</style>
</head>
<body>

<h2>The border-style Property</h2>
<p>This property specifies what kind of border to display:</p>

<p class="dotted">A dotted border.</p>
<p class="dashed">A dashed border.</p>
<p class="solid">A solid border.</p>
<p class="double">A double border.</p>
<p class="groove">A groove border.</p>
<p class="ridge">A ridge border.</p>
<p class="inset">An inset border.</p>
<p class="outset">An outset border.</p>
<p class="none">No border.</p>
<p class="hidden">A hidden border.</p>
<p class="mix">A mixed border.</p>

</body>
</html>

宽度

border-width指定宽度

可以设置为px, pt, cm, em等单位，也可以使用thin, medium, thick等值

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52


<!DOCTYPE html>
<html>
<head>
<style>
p.one {
  border-style: solid;
  border-width: 5px;
}

p.two {
  border-style: solid;
  border-width: medium;
}

p.three {
  border-style: dotted;
  border-width: 2px;
}

p.four {
  border-style: dotted;
  border-width: thick;
}

p.five {
  border-style: double;
  border-width: 15px;
}

p.six {
  border-style: double;
  border-width: thick;
}
</style>
</head>
<body>

<h2>The border-width Property</h2>
<p>This property specifies the width of the four borders:</p>

<p class="one">Some text.</p>
<p class="two">Some text.</p>
<p class="three">Some text.</p>
<p class="four">Some text.</p>
<p class="five">Some text.</p>
<p class="six">Some text.</p>

<p><b>Note:</b> The "border-width" property does not work if it is used alone. 
Always specify the "border-style" property to set the borders first.</p>

</body>
</html>

颜色

border-color指定边框颜色

可以使用

指定的名字，比如 red、blue
十六进制，比如 #ff0000
RGB，比如 rgb(255,0,0)
HSL，比如 hsl(0, 100%, 50%)
transparent，表示透明

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33


<!DOCTYPE html>
<html>
<head>
<style>
p.one {
  border-style: solid;
  border-color: red;
}

p.two {
  border-style: solid;
  border-color: green;
} 

p.three {
  border-style: dotted;
  border-color: blue;
} 
</style>
</head>
<body>

<h2>The border-color Property</h2>
<p>This property specifies the color of the four borders:</p>

<p class="one">A solid red border</p>
<p class="two">A solid green border</p>
<p class="three">A dotted blue border</p>

<p><b>Note:</b> The "border-color" property does not work if it is used alone. Use the "border-style" property to set the borders first.</p>

</body>
</html>

侧边

根据前面的内容，知道了边框的样式，宽度，颜色，在此基础上，还可以单独指定某一边的边框样式（top、right、bottom、left）

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19


<!DOCTYPE html>
<html>
<head>
<style>
p {
  border-top-style: dotted;
  border-right-style: solid;
  border-bottom-style: dotted;
  border-left-style: solid;
}
</style>
</head>
<body>

<h2>Individual Border Sides</h2>
<p>2 different border styles.</p>

</body>
</html>

除了使用特定侧边的属性，也可以只使用 border-style单个属性达到同样的效果，后续跟上不同的值有不同的效果，按照顺序为：上右下左。

四个值：上右下左
三个值：上右下，左跟随着右
两个值：上右，下随着上，左跟随着右
一个值：四边相同

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38


<!DOCTYPE html>
<html>
<head>
<style>
body {
  text-align: center;
}
/* Four values */
p.four {
  border-style: dotted solid double dashed;
}

/* Three values */
p.three {
  border-style: dotted solid double;
}

/* Two values */
p.two {
  border-style: dotted solid;
}

/* One value */
p.one {
  border-style: dotted;
}
</style>
</head>
<body>

<h2>Individual Border Sides</h2>
<p class="four">4 different border styles.</p>
<p class="three">3 different border styles.</p>
<p class="two">2 different border styles.</p>
<p class="one">1 border style.</p>

</body>
</html>

简写

由于属性太多，为了方便书写，可以使用一个属性 border来描述边框

border: border-width border-style(required) border-color

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17


<!DOCTYPE html>
<html>
<head>
<style>
p {
  border: 5px solid red;
}
</style>
</head>
<body>

<h2>The border Property</h2>

<p>This property is a shorthand property for border-width, border-style, and border-color.</p>

</body>
</html>

圆角

默认边框角度是直角，可以通过 border-radius属性指定边框角度弯曲状态

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40


<!DOCTYPE html>
<html>
<head>
<style>
p.normal {
  border: 2px solid red;
  padding: 5px;
}

p.round1 {
  border: 2px solid red;
  border-radius: 5px;
  padding: 5px;
}

p.round2 {
  border: 2px solid red;
  border-radius: 8px;
  padding: 5px;
}

p.round3 {
  border: 2px solid red;
  border-radius: 12px;
  padding: 5px;
}
</style>
</head>
<body>

<h2>The border-radius Property</h2>
<p>This property is used to add rounded borders to an element:</p>

<p class="normal">Normal border</p>
<p class="round1">Round border</p>
<p class="round2">Rounder border</p>
<p class="round3">Roundest border</p>

</body>
</html>

图片

边框也可以设置图片

border-image可以设置边框的图片

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18


<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .box {
            border: 5px solid;
            /* 上 右 下 左 */
            border-image: linear-gradient(to right, #0066ff, #ff32d6) 1 0 1 1;
        }
    </style>
</head>
<body>
    <div class="box">border image</div>
</body>
</html>