左下边框圆角 - CSS（层叠样式表） 编辑

Summary

总览

border-bottom-left-radius 这个css属性设置元素左下角的圆角。圆角可以是圆或椭圆（注：应为圆或椭圆的一部分），或者当其中一个值为0时，圆角将不被设置，这时这个角将展示为直角。

一个无论是图像或颜色的背景，都会在边框上被裁剪，即使背景是圆角的; 裁剪的确切位置由 background-clip 属性定义.

语法

/* 圆形 */
/* border-bottom-left-radius: radius */
border-bottom-left-radius: 3px;

/* 椭圆形 */
/* border-bottom-left-radius: 水平方向 垂直方向 */
border-bottom-left-radius: 0.5em 1em;

border-bottom-left-radius: inherit;

where:

radius

Is a <length> or a <percentage> denoting the radius of the circle to use for the border in that corner.

horizontal

Is a <length> or a <percentage> denoting the horizontal semi-major axis of the ellipsis to use for the border in that corner.

vertical

Is a <length> or a <percentage> denoting the vertical semi-major axis of the ellipsis to use for the border in that corner.

Values

<length-percentage>

Denotes the size of the circle radius or the semi-major and semi-minor axes of the ellipsis. As absolute length it can be expressed in any unit allowed by the CSS <length> data type. Percentages for the horizontal axis refer to the width of the box, percentages for the vertical axis refer to the height of the box. Negative values are invalid.

Formal syntax

<length-percentage>{1,2}
where 
<length-percentage> = <length> | <percentage>

Examples

div {
  border-bottom-left-radius: 40px 40px;
}

div {
  border-bottom-left-radius: 40px 20px;
}

div {
  border-bottom-left-radius: 40%;
}

div {
  border-bottom-left-radius: 40%;
}

div {
  border-bottom-left-radius:40%;
  border-style: black 3px double;
  background-color: rgb(250,20,70);
  background-clip: content-box;
}

Specifications

Browser compatibility

• Desktop
• Mobile

[1] The prefixed version (allowed from Firefox 1 to Firefox 12) of this property uses a different name, -moz-border-radius-bottomleft, than the final property as Mozilla implemented it before the final name was coined.

[2] Before Firefox 4, the <percentage> was relative to the width of the box even when specifying the radius for a height). This implied that -moz-border-radius-bottomleft was always drawing an arc of circle, and never an ellipse, when followed by a single value.

[3] Prior to Gecko 50.0 (Firefox 50.0 / Thunderbird 50.0 / SeaMonkey 2.47), border styles of rounded corners were always rendered as if border-style was solid. This has been fixed in Gecko 50.0.

In addition to the unprefixed support, Gecko 44.0 (Firefox 44.0 / Thunderbird 44.0 / SeaMonkey 2.41) added support for a -webkit prefixed version of the property for web compatibility reasons behind the preference layout.css.prefixes.webkit, defaulting to false. Since Gecko 49.0 (Firefox 49.0 / Thunderbird 49.0 / SeaMonkey 2.46) the preference defaults to true.

See also

The border-radius-related CSS properties: the CSS shorthand border-radius, the properties for the other corners: border-top-right-radius, border-bottom-right-radius, and border-top-left-radius.