2019年更新
现在最好的选择是- flexbox。多年来,所有东西都很好地支持它。去吧,不要回头。下面是一个flexbox的代码示例:
正文,HTML{宽度:100%;高度:100%;保证金:0;填充:0}
.row-container{显示:flex;宽度:100%;高度:100%;flex-direction:列;背景颜色:蓝色;溢出:隐藏;}
.第一行{background-color:石灰;}
.第二行{flex-grow: 1;边界:没有;保证金:0;填充:0;}
< div class = "行容器”>
< div class = "板凳”>
< / p > < p >一些文本
<p>和一些更多的文本</p>
< / div >
<iframe src="https://jsfiddle.net/about" class="second-row"></iframe>
< / div >
剩下的答案留给学习和历史原因。
关键是要明白这100%是什么。阅读CSS规范可以帮助你。
To make a long story short - there is such a thing as "containing block" - which is not necessary the parent element. Simply said, it is the first element up the hierarchy that has position:relative or position:absolute. Or the body element itself if there is nothing else. So, when you say "width: 100%", it checks the width of the "containing block" and sets the width of your element to the same size. If there was something else there, then you might get contents of a "containing block" that are larger than itself (thus "overflowing").
身高也有同样的作用。只有一个例外。你不能让高度达到浏览器窗口的100%。最顶层的元素是body(或html?)不确定)元素,并且该元素的延伸足以包含其内容。指定高度:100%对它没有影响,因为它没有“父元素”来测量100%。窗口本身不算数。;)
要让某样东西伸展到窗口的100%,你有两个选择:
使用JavaScript
Don't use DOCTYPE. This is not a good practice, but it puts the browsers in "quirks mode", in which you can do height="100%" on elements and it will stretch them to the window size. Do note, that the rest of your page will probably have to be changed too to accommodate for the DOCTYPE changes.
Update: I'm not sure if I wasn't wrong already when I posted this, but this certainly is outdated now. Today you can do this in your stylesheet: html, body { height: 100% } and it will actually stretch to the whole of your viewport. Even with a DOCTYPE. min-height: 100% could also be useful, depending on your situation.
And I wouldn't advise anyone to make a quirks-mode document anymore either, because it causes way more headaches than solves them. Every browser has a different quirks-mode, so getting your page to look consistently across browsers becomes two orders of magnitude more difficult. Use a DOCTYPE. Always. Preferably the HTML5 one - <!DOCTYPE html>. It's easy to remember and works like a charm in all browsers, even the 10 years old ones.
The only exception is when you have to support something like IE5 or something. If you're there, then you're on your own anyway. Those ancient browsers are nothing like the browsers today, and little advice that is given here will help you with them. On the bright side, if you're there, you probably just have to support ONE kind of browser, which gets rid of the compatibility problems.
Good luck!
Update 2: Hey, it's been a long time! 6 years later, new options are on the scene. I just had a discussion in the comments below, here are more tricks for you that work in today's browsers.
Option 1 - absolute positioning. Nice and clean for when you know the precise height of the first part.
body, html {width: 100%; height: 100%; margin: 0; padding: 0}
.first-row {position: absolute;top: 0; left: 0; right: 0; height: 100px; background-color: lime;}
.second-row {position: absolute; top: 100px; left: 0; right: 0; bottom: 0; background-color: red }
.second-row iframe {display: block; width: 100%; height: 100%; border: none;}
<div class="first-row">
<p>Some text</p>
<p>And some more text</p>
</div>
<div class="second-row">
<iframe src="https://jsfiddle.net/about"></iframe>
</div>
Some notes - the second-row container is needed because bottom: 0 and right: 0 doesn't work on iframes for some reason. Something to do with in being a "replaced" element. But width: 100% and height: 100% works just fine. display: block is needed because it's an inline element by default and whitespace starts creating weird overflows otherwise.
Option 2 - tables. Works when you don't know the height of the first part. You can use either actual <table> tags or do it the fancy way with display: table. I'll go for the latter because it seems to be in fashion these days.
body, html {width: 100%; height: 100%; margin: 0; padding: 0}
.row-container {display: table; empty-cells: show; border-collapse: collapse; width: 100%; height: 100%;}
.first-row {display: table-row; overflow: auto; background-color: lime;}
.second-row {display: table-row; height: 100%; background-color: red; overflow: hidden }
.second-row iframe {width: 100%; height: 100%; border: none; margin: 0; padding: 0; display: block;}
<div class="row-container">
<div class="first-row">
<p>Some text</p>
<p>And some more text</p>
</div>
<div class="second-row">
<iframe src="https://jsfiddle.net/about"></iframe>
</div>
</div>
Some notes - the overflow: auto makes sure that the row always includes all of its contents. Otherwise floating elements can sometimes overflow. The height: 100% on the second row makes sure it expands as much as it can squeezing the first row as small as it gets.
Recommended: Option 3 - flexbox - The cleanest one of them all.
body, html {width: 100%; height: 100%; margin: 0; padding: 0}
.row-container {display: flex; width: 100%; height: 100%; flex-direction: column; background-color: blue; overflow: hidden;}
.first-row {background-color: lime; }
.second-row { flex-grow: 1; border: none; margin: 0; padding: 0; }
<div class="row-container">
<div class="first-row">
<p>Some text</p>
<p>And some more text</p>
</div>
<iframe src="https://jsfiddle.net/about" class="second-row"></iframe>
</div>
Some notes - the overflow: hidden is because the iframe still generates some sort of overflow even with display: block in this case. It isn't visible in the fullscreen view or the snippet editor, but the small preview window gets an extra scrollbar. No idea what that is, iframes are weird.