CSS RGBA边框/背景alpha双 [英] CSS RGBA border / background alpha double
问题描述
我在一个有很多透明度的网站上工作，我想我会尝试完全在RGBA构建它，然后做回退的IE。我需要一个facebox样式的边框效果，其中外部边框是圆形的，并且比它包围的框的背景不透明。
I'm working on a website that has a lot of transparency involved, and I thought I would try to build it entirely in RGBA and then do fallbacks for IE. I need a "facebox" style border effect, where the outer border is rounded and is less opaque than the background of the box it surrounds.
最后一个例子从 http://24ways.org/2009/working-with-rgba-colour 似乎建议这是可能的，但我似乎无法得到它的工作。当我尝试以下：
The last example from http://24ways.org/2009/working-with-rgba-colour seems to suggest that it's possible, but I can't seem to get it to work. When I try the following:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<title>RGBA Test</title>
<style type='text/css'>
body {
background: #000;
color: #fff;
}
#container {
width: 700px;
margin: 0 auto;
background: rgba(255, 255, 255, 0.2);
border: 10px solid rgba(255, 255, 255, 0.1);
padding: 20px;
}
</style>
</head>
<body>
<div id='container'>
This should look like a facebox.
</div>
</body></html>
看起来像是元素边框下方的背景extends，这会导致像素值得到加在一起。因此，当背景和边界都是半透明的时，边界总是比元素的背景更不透明。这正好与我想实现的相反，但它似乎应该是可能的基于我看到的例子。
It seems like the background "extends" underneath the border of the element, which causes the pixel values to get added together. Thus, when both the background and the border are semi-transparent, the border will ALWAYS be more opaque than the background of the element. This is exactly the opposite of what I am trying to achieve, but it seems like it should be possible based on the examples I've seen.
我还应该添加我不能使用容器内的另一个元素，因为我也要在容器上使用border-radius来获取圆角，而webkit如果分配了一个背景，就会对子元素的角落进行平方，
I should also add that I can't use another element inside the container, because I'm also going to use a border-radius on the container to get rounded corners, and webkit squares the corners of the child elements if they have a background assigned, which would essentially mean a rounded outer border with square contents.
对不起，我不能发布此图片...显然我没有足够的代表来发布图片。
Sorry I can't post an image of this... Apparently I don't have enough rep to post an image.
推荐答案
您可以使用新的 background-clip：padding-box; 属性来得到这个。它计算背景从框中开始的位置。
有关更多详细信息和示例，请查看此处
You can use the new background-clip: padding-box; property to get this going. It calculates where from should the background start within a box.
For more details and examples, check here
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