有一个直接的CSS方法，使一个元素的边界半透明的东西像这样?
border-opacity: 0.7;
如果没有，有没有人知道我如何在不使用图像的情况下做到这一点?
当前回答
试试这个:
<h2>Snippet for making borders transparent</h2>
<div>
<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer nec odio. Praesent libero. Sed cursus ante dapibus diam. Sed nisi. Nulla quis sem at nibh elementum imperdiet. Duis sagittis ipsum. Praesent mauris. Fusce nec tellus sed augue semper porta.
Mauris massa. Vestibulum lacinia arcu eget nulla. <b>Lorem ipsum dolor sit amet, consectetur adipiscing elit</b>. Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos. Curabitur sodales ligula in libero. Sed dignissim
lacinia nunc. <i>Lorem ipsum dolor sit amet, consectetur adipiscing elit</i>. Curabitur tortor. Pellentesque nibh. Aenean quam. In scelerisque sem at dolor. Maecenas mattis. Sed convallis tristique sem. Proin ut ligula vel nunc egestas porttitor.
<i>Lorem ipsum dolor sit amet, consectetur adipiscing elit</i>. Morbi lectus risus, iaculis vel, suscipit quis, luctus non, massa. Fusce ac turpis quis ligula lacinia aliquet. Mauris ipsum. Nulla metus metus, ullamcorper vel, tincidunt sed, euismod
in, nibh. Quisque volutpat condimentum velit. Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos. Nam nec ante. Sed lacinia, urna non tincidunt mattis, tortor neque adipiscing diam, a cursus ipsum ante quis
turpis. Nulla facilisi. Ut fringilla. Suspendisse potenti. Nunc feugiat mi a tellus consequat imperdiet. Vestibulum sapien. Proin quam. Etiam ultrices. <b>Nam nec ante</b>. Suspendisse in justo eu magna luctus suscipit. Sed lectus. <i>Sed convallis tristique sem</i>.
Integer euismod lacus luctus magna. <b>Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos</b>. Quisque cursus, metus vitae pharetra auctor, sem massa mattis sem, at interdum magna augue eget diam. Vestibulum
ante ipsum primis in faucibus orci luctus et ultrices posuere cubilia Curae; Morbi lacinia molestie dui. Praesent blandit dolor. Sed non quam. In vel mi sit amet augue congue elementum. Morbi in ipsum sit amet pede facilisis laoreet. Donec lacus nunc,
viverra nec, blandit vel, egestas et, augue. Vestibulum tincidunt malesuada tellus. Ut ultrices ultrices enim. <b>Suspendisse in justo eu magna luctus suscipit</b>. Curabitur sit amet mauris. Morbi in dui quis est pulvinar ullamcorper. </p>
</div>
<div id="transparentBorder">
This <div> has transparent borders.
</div>
这里是我们神奇的CSS..
* {
padding: 10pt;
font: 13px/1.5 Helvetica Neue, Arial, Helvetica, 'Liberation Sans', FreeSans, sans-serif;
}
b {
font-weight: bold;
}
i {
font-style: oblique;
}
H2 {
font-size: 2em;
}
div[id='transparentBorder'] {
height: 100px;
width: 200px;
padding: 10px;
position: absolute;
top: 40%;
left: 30%;
text-align: center;
background: Black;
border-radius: 4px;
border: 10pt solid rgba(0, 0, 0, 0.5);
-moz-background-clip: border;
/* Firefox 3.6 */
-webkit-background-clip: border;
/* Safari 4? Chrome 6? */
background-clip: border-box;
/* Firefox 4, Safari 5, Opera 10, IE 9 */
-moz-background-clip: padding;
/* Firefox 3.6 */
-webkit-background-clip: padding;
/* Safari 4? Chrome 6? */
background-clip: padding-box;
/* Firefox 4, Safari 5, Opera 10, IE 9 */
text-align: center;
margin: 0;
color: #fff;
cursor: pointer;
}
点击这里查看演示。
其他回答
你也可以考虑其他的边框样式(虚线，虚线)来让边框部分完全透明:
http://jsfiddle.net/c1rvp3ga
身体{ 背景:url (http://i.imgur.com/pr86mh.jpg); ｝ # foo { 边框:5px虚线#b00; 背景:# ddd; background-clip: padding-box; 填充:8 px; 宽度:100 px; 保证金:30 px; ｝ <p id=foo>一些内容</p>
试试这个:
<h2>Snippet for making borders transparent</h2>
<div>
<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer nec odio. Praesent libero. Sed cursus ante dapibus diam. Sed nisi. Nulla quis sem at nibh elementum imperdiet. Duis sagittis ipsum. Praesent mauris. Fusce nec tellus sed augue semper porta.
Mauris massa. Vestibulum lacinia arcu eget nulla. <b>Lorem ipsum dolor sit amet, consectetur adipiscing elit</b>. Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos. Curabitur sodales ligula in libero. Sed dignissim
lacinia nunc. <i>Lorem ipsum dolor sit amet, consectetur adipiscing elit</i>. Curabitur tortor. Pellentesque nibh. Aenean quam. In scelerisque sem at dolor. Maecenas mattis. Sed convallis tristique sem. Proin ut ligula vel nunc egestas porttitor.
<i>Lorem ipsum dolor sit amet, consectetur adipiscing elit</i>. Morbi lectus risus, iaculis vel, suscipit quis, luctus non, massa. Fusce ac turpis quis ligula lacinia aliquet. Mauris ipsum. Nulla metus metus, ullamcorper vel, tincidunt sed, euismod
in, nibh. Quisque volutpat condimentum velit. Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos. Nam nec ante. Sed lacinia, urna non tincidunt mattis, tortor neque adipiscing diam, a cursus ipsum ante quis
turpis. Nulla facilisi. Ut fringilla. Suspendisse potenti. Nunc feugiat mi a tellus consequat imperdiet. Vestibulum sapien. Proin quam. Etiam ultrices. <b>Nam nec ante</b>. Suspendisse in justo eu magna luctus suscipit. Sed lectus. <i>Sed convallis tristique sem</i>.
Integer euismod lacus luctus magna. <b>Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos</b>. Quisque cursus, metus vitae pharetra auctor, sem massa mattis sem, at interdum magna augue eget diam. Vestibulum
ante ipsum primis in faucibus orci luctus et ultrices posuere cubilia Curae; Morbi lacinia molestie dui. Praesent blandit dolor. Sed non quam. In vel mi sit amet augue congue elementum. Morbi in ipsum sit amet pede facilisis laoreet. Donec lacus nunc,
viverra nec, blandit vel, egestas et, augue. Vestibulum tincidunt malesuada tellus. Ut ultrices ultrices enim. <b>Suspendisse in justo eu magna luctus suscipit</b>. Curabitur sit amet mauris. Morbi in dui quis est pulvinar ullamcorper. </p>
</div>
<div id="transparentBorder">
This <div> has transparent borders.
</div>
这里是我们神奇的CSS..
* {
padding: 10pt;
font: 13px/1.5 Helvetica Neue, Arial, Helvetica, 'Liberation Sans', FreeSans, sans-serif;
}
b {
font-weight: bold;
}
i {
font-style: oblique;
}
H2 {
font-size: 2em;
}
div[id='transparentBorder'] {
height: 100px;
width: 200px;
padding: 10px;
position: absolute;
top: 40%;
left: 30%;
text-align: center;
background: Black;
border-radius: 4px;
border: 10pt solid rgba(0, 0, 0, 0.5);
-moz-background-clip: border;
/* Firefox 3.6 */
-webkit-background-clip: border;
/* Safari 4? Chrome 6? */
background-clip: border-box;
/* Firefox 4, Safari 5, Opera 10, IE 9 */
-moz-background-clip: padding;
/* Firefox 3.6 */
-webkit-background-clip: padding;
/* Safari 4? Chrome 6? */
background-clip: padding-box;
/* Firefox 4, Safari 5, Opera 10, IE 9 */
text-align: center;
margin: 0;
color: #fff;
cursor: pointer;
}
点击这里查看演示。
在这里稍微跳出框框思考一下:如果您正在使用SVG基本形状，您可以使用笔画、笔画宽度(浏览器支持> 97%)和笔画不透明度(浏览器支持> 99%)的组合来完成基本上与OP要求的相同的事情。
例如，这样的声明:
circle {
stroke: blue;
stroke-width: 5px;
stroke-opacity: 0.4
}
将在<circle>的周长添加一个半透明的蓝色晕，填充#000。
这个JSFiddle提供了几个SVG基本形状的演示。小提琴使用红色填充和蓝色描边来突出描边和边框之间的主要区别-一半的描边宽度在基本形状的周长内。
这就给出了一个“双边框”外观(从外部到每个基本形状的中心:蓝色->(蓝色+红色=紫色)->红色)，这是不可能仅用CSS边框实现的(但边框+轮廓可以-参见上面的JSFiddle，使用<div>的例子)，并且很难实现(在径向基本形状的情况下)用径向梯度()。
正如其他人所提到的，CSS3支持rgba(…)语法来指定带有不透明度(alpha)值的边框颜色。
这里有一个快速的JSFiddle演示，如果你想检查它。
它适用于Safari和Chrome(可能适用于所有webkit浏览器)。 它可以在Firefox中运行 我怀疑它在IE中是否能正常工作，但我怀疑有一些过滤器或行为可以使它工作。
还有CSS RGBA边框/背景alpha double，这表明了一些其他问题——即，边框呈现在您指定的任何背景颜色(或背景图像)之上;因此在许多情况下限制了边界alpha的有用性。
这很简单，使用一个0偏移量的实体阴影:
#foo {
border-radius: 1px;
box-shadow: 0px 0px 0px 8px rgba(0,0,0,0.3);
}
此外，如果您为元素设置一个边界半径，它会为您提供非常圆润的边界
jsFiddle演示
