outline-color - CSS（层叠样式表） 编辑

outline-color CSS属性 被用于设置一个元素轮廓的颜色.

这个展示项目的源码由GitHub托管 . 如果你对这个展示项目感兴趣,可以clone https://github.com/mdn/interactive-examples 并向我们提交一个pull request.

大多时候使用outline而不是outline-style,outline-width 和 outline-color会更方便.

元素轮廓是绘制于元素周围的一条线，位于border的外围，使元素突出.不像border,轮廓在元素的frame外绘制并且可能与其他元素重叠.而border不会出现这种现象(除非故意).

语法

/* <color> values */
outline-color: #f92525;
outline-color: rgb(30,222,121);
outline-color: blue;

/* Keyword value */
outline-color: invert;

/* Global values */
outline-color: inherit;
outline-color: initial;
outline-color: unset;

outline-color可用以下这些值.

Values

<color>

轮廓颜色,规则同 <color>.

invert

反色,用于确认轮廓的显示.注意不是所有浏览器都支持该属性,若不则该属性无效.

正规语法

<color> | invert
where 
<color> = <rgb()> | <rgba()> | <hsl()> | <hsla()> | <hex-color> | <named-color> | currentcolor | <deprecated-system-color>
where 
<rgb()> = rgb( <percentage>{3} [ / <alpha-value> ]? ) | rgb( <number>{3} [ / <alpha-value> ]? ) | rgb( <percentage>#{3} , <alpha-value>? ) | rgb( <number>#{3} , <alpha-value>? )
<rgba()> = rgba( <percentage>{3} [ / <alpha-value> ]? ) | rgba( <number>{3} [ / <alpha-value> ]? ) | rgba( <percentage>#{3} , <alpha-value>? ) | rgba( <number>#{3} , <alpha-value>? )
<hsl()> = hsl( <hue> <percentage> <percentage> [ / <alpha-value> ]? ) | hsl( <hue>, <percentage>, <percentage>, <alpha-value>? )
<hsla()> = hsla( <hue> <percentage> <percentage> [ / <alpha-value> ]? ) | hsla( <hue>, <percentage>, <percentage>, <alpha-value>? )
where 
<alpha-value> = <number> | <percentage>
<hue> = <number> | <angle>

例子

HTML

<p>My outline is blue, as you can see.</p>

CSS

p {
  outline: 2px solid;      /* Set the outline width and style */
  outline-color: #0000FF;  /* Make the outline blue */
  margin: 5px;
}

Accessibility concerns

Custom focus styles commonly involve making adjustments to the outline property. If the color of the outline is adjusted, it is important to ensure that the contrast ratio between it and the background the outline is placed over is high enough that people experiencing low vision conditions will be able to perceive it.

Color contrast ratio is determined by comparing the luminosity of the text and background color values. In order to meet current Web Content Accessibility Guidelines (WCAG), a ratio of 4.5:1 is required for text content and 3:1 for larger text such as headings. Large text is defined as 18.66px and bold or larger, or 24px or larger.

• WebAIM: Color Contrast Checker
• MDN Understanding WCAG, Guideline 1.4 explanations
• Understanding Success Criterion 1.4.3  | W3C Understanding WCAG 2.0

规范

Specification	Status	Comment
CSS Basic User Interface Module Level 3 outline-color	Recommendation	No change.
CSS Transitions outline-color	Working Draft	Defines outline-color as animatable.
CSS Level 2 (Revision 1) outline-color	Recommendation	Initial definition.

初始值	invert, for browsers supporting it, currentColor for the other
适用元素	all elements
是否是继承属性	否
计算值	For the keyword invert, the computed value is invert. For the color value, if the value is translucent, the computed value will be the rgba() corresponding one. If it isn't, it will be the rgb() corresponding one. The transparent keyword maps to rgba(0,0,0,0).
Animation type	a color

浏览器兼容性

BCD tables only load in the browser

The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

相关链接

• <color> 数据类型
• 其他与颜色有关的属性: color, background-color, border-color, text-decoration-color, text-emphasis-color, text-shadow, caret-color, 和column-rule-color
• Applying color to HTML elements using CSS