3.2 CSS3边框颜色属性
3.2.1 border-color
属性的语法及参数
border-color
的语法看上去和CSS1中的完全相同,但为了避免与border-color
属性的原功能发生冲突,CSS3在这个属性上做出了一定的修改。语法如下:
border-color : [ <color> | transparent ] { 1, 4} | inherit
换句话说,如果使用border-color
这种缩写语法,将不会有任何效果,必须将这个border-color
标准写法拆分成四个边框,使用多颜色才会有效果。
border-top-colors : [ <color> | transparent ] { 1, 4} | inherit
border-right-colors : [ <color> | transparent ] { 1, 4} | inherit
;border-bottom-colors : [ <color> | transparent ] { 1, 4} | inherit
;border-left-colors : [ <color> | transparent ] { 1, 4} | inherit
;
以上四个属性中color 是复数colors,如果在书写过程中要是少了s
字母是错误的,没有任何反应。由于CSS3的border-color
属性还没有成为标准规范,为了让不同的浏览器都能正常渲染,有必要加上浏览器前缀。
border-color
属性的参数其实很简单,就是颜色值<color>
,可以为任意合法的颜色值或者颜色值列表。当只设置一个颜色时,效果和CSS1中的border-color
效果一样。只有设置了n个颜色,并且边框宽度也为n像素,就可以使用CSS3的border-color
属性设置n个颜色,每种颜色显示1像素,如果宽度值大于颜色数量的值,最后一种颜色用于显示剩下的宽度。
3.2.2 浏览器兼容性
目前(2016年12月8日)仅有firefox支持,需要带-moz-
前缀。
3.2.3 border-color
属性的优势
在CSS2中实现多颜色的边框效果,无外乎两种方法,其一通过添加额外的标签,在每个标签上设置不同的颜色,其二就是通过背景图片来制作。这两种方法和CSS3的border-color
相比都略显弊端,第一种多了标签,使结构冗余,第二种方法背景图片不好维护,特别是在改变边框颜色之时更是麻烦。
3.2.4 实现体检:立体渐变边框效果
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>border-color 制作立体渐变边框效果</title>
<style>
div{
width: 500px;
height: 100px;
border: 10px solid transparent;
border-radius: 15px 0 15px;
-moz-border-top-colors: #a0a #909 #808 #707 #606 #505 #404 #303;
-moz-border-right-colors: #a0a #909 #808 #707 #606 #505 #404 #303;
-moz-border-bottom-colors: #a0a #909 #808 #707 #606 #505 #404 #303;
-moz-border-left-colors: #a0a #909 #808 #707 #606 #505 #404 #303;
}
</style>
</head>
<body>
<div></div>
</body>
</html>
*:first-child {
margin-top: 0 !important;
}
body>*:last-child {
margin-bottom: 0 !important;
}
/* BLOCKS
=============================================================================*/
p, blockquote, ul, ol, dl, table, pre {
margin: 15px 0;
}
/* HEADERS
=============================================================================*/
h1, h2, h3, h4, h5, h6 {
margin: 20px 0 10px;
padding: 0;
font-weight: bold;
-webkit-font-smoothing: antialiased;
}
h1 tt, h1 code, h2 tt, h2 code, h3 tt, h3 code, h4 tt, h4 code, h5 tt, h5 code, h6 tt, h6 code {
font-size: inherit;
}
h1 {
font-size: 28px;
color: #000;
}
h2 {
font-size: 24px;
border-bottom: 1px solid #ccc;
color: #000;
}
h3 {
font-size: 18px;
}
h4 {
font-size: 16px;
}
h5 {
font-size: 14px;
}
h6 {
color: #777;
font-size: 14px;
}
body>h2:first-child, body>h1:first-child, body>h1:first-child+h2, body>h3:first-child, body>h4:first-child, body>h5:first-child, body>h6:first-child {
margin-top: 0;
padding-top: 0;
}
a:first-child h1, a:first-child h2, a:first-child h3, a:first-child h4, a:first-child h5, a:first-child h6 {
margin-top: 0;
padding-top: 0;
}
h1+p, h2+p, h3+p, h4+p, h5+p, h6+p {
margin-top: 10px;
}
/* LINKS
=============================================================================*/
a {
color: #4183C4;
text-decoration: none;
}
a:hover {
text-decoration: underline;
}
/* LISTS
=============================================================================*/
ul, ol {
padding-left: 30px;
}
ul li > :first-child,
ol li > :first-child,
ul li ul:first-of-type,
ol li ol:first-of-type,
ul li ol:first-of-type,
ol li ul:first-of-type {
margin-top: 0px;
}
ul ul, ul ol, ol ol, ol ul {
margin-bottom: 0;
}
dl {
padding: 0;
}
dl dt {
font-size: 14px;
font-weight: bold;
font-style: italic;
padding: 0;
margin: 15px 0 5px;
}
dl dt:first-child {
padding: 0;
}
dl dt>:first-child {
margin-top: 0px;
}
dl dt>:last-child {
margin-bottom: 0px;
}
dl dd {
margin: 0 0 15px;
padding: 0 15px;
}
dl dd>:first-child {
margin-top: 0px;
}
dl dd>:last-child {
margin-bottom: 0px;
}
/* CODE
=============================================================================*/
pre, code, tt {
font-size: 12px;
font-family: Consolas, "Liberation Mono", Courier, monospace;
}
code, tt {
margin: 0 0px;
padding: 0px 0px;
white-space: nowrap;
border: 1px solid #eaeaea;
background-color: #f8f8f8;
border-radius: 3px;
}
pre>code {
margin: 0;
padding: 0;
white-space: pre;
border: none;
background: transparent;
}
pre {
background-color: #f8f8f8;
border: 1px solid #ccc;
font-size: 13px;
line-height: 19px;
overflow: auto;
padding: 6px 10px;
border-radius: 3px;
}
pre code, pre tt {
background-color: transparent;
border: none;
}
kbd {
-moz-border-bottom-colors: none;
-moz-border-left-colors: none;
-moz-border-right-colors: none;
-moz-border-top-colors: none;
background-color: #DDDDDD;
background-image: linear-gradient(#F1F1F1, #DDDDDD);
background-repeat: repeat-x;
border-color: #DDDDDD #CCCCCC #CCCCCC #DDDDDD;
border-image: none;
border-radius: 2px 2px 2px 2px;
border-style: solid;
border-width: 1px;
font-family: "Helvetica Neue",Helvetica,Arial,sans-serif;
line-height: 10px;
padding: 1px 4px;
}
/* QUOTES
=============================================================================*/
blockquote {
border-left: 4px solid #DDD;
padding: 0 15px;
color: #777;
}
blockquote>:first-child {
margin-top: 0px;
}
blockquote>:last-child {
margin-bottom: 0px;
}
/* HORIZONTAL RULES
=============================================================================*/
hr {
clear: both;
margin: 15px 0;
height: 0px;
overflow: hidden;
border: none;
background: transparent;
border-bottom: 4px solid #ddd;
padding: 0;
}
/* TABLES
=============================================================================*/
table th {
font-weight: bold;
}
table th, table td {
border: 1px solid #ccc;
padding: 6px 13px;
}
table tr {
border-top: 1px solid #ccc;
background-color: #fff;
}
table tr:nth-child(2n) {
background-color: #f8f8f8;
}
/* IMAGES
=============================================================================*/
img {
max-width: 100%
}
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