Why can't I make my div 100% height if I use an HTML5 doctype? How do I get it 100% height

I am working on getting the layout sorted for a pretty simple gallery webapp, but when I use an HTML5 doctype declaration, the height of some of my divs (which were 100%) get shrunk right down, and I can't seem to plump them back up using CSS.

My HTML is at https://dl.dropbox.com/u/16178847/eyewitness/b/index.html and css is at https://dl.dropbox.com/u/16178847/eyewitness/b/style.css

If I remove the HTML5 doctype declaration, all is as I want it to be, but I really want to use the proper HTML5 doctype declaration.
If I set the doctype to HTML5 and make no changes, the div with the photo and the footer divs are not visible, presumably because they are 0px high.
If I set the doctype to HTML5 and make the body { height: 100px } and .container { height: 100px } or .container { height: 100% }, it becomes visible, but what I need is it to be is full height rather than a height in pixels.
If I try to do the same as above, but with the body { height: 100% } the photo and footer divs are not visible again.

What do I need to do to get it 100% in height so that my photo and footer divs are full height?

Only if the parent element has a defined height, i..e not a value of auto. If that has 100% height, the parent's parent height must be defined, too. This could go until to the html root element.

So set the height of the html and the body element to 100%, as well as every single ancestor element of that element that you wish to have the 100% height in the first place.

Indeed, to make it work do as follow:

<!DOCTYPE html>
<html>
<head>
  <title>Vertical Scrolling Demo</title>
  <style>
    html, body {
      width: 100%;
      height: 100%;
      background: white;
      margin:0;
      padding:0;
    }
    .page {
      min-height: 100%;
      width: 100%;
    }
  </style>
</head>
<body>
  <div id="nav" class="page">
    <ul>
      <li><a href="#about">About</a></li>
      <li><a href="#portfolio">Portfolio</a></li>
      <li><a href="#contact">Contact</a></li>
    </ul>
  </div>
  <div id="page1" class="page">
    <h1><a name="about">about</a></h1>
    About page content goes here.
  </div>
  <div id="page2" class="page">
    <h1><a name="portfolio">portfolio</a></h1>
    Portfolio page content goes here.
  </div>
  <div id="page3" class="page">
    <h1><a name="contact">contact</a></h1>
    Contact page content goes here.
  </div>
</body>
</html>

I got stuck into a similar problema to size a canvas, so here is what i did and worked perfectly.

Besides doing the:

body{ width: 100%; heigh: 100%;}

Set the desired element like this:

.desired-element{ width: 100vw; heigh: 100vh}

In that way you are assured to have 100% of the view port in width and height. vw stands for viewwidth and vh stands for viewheight

I hope this helps someone

来源：https://stackoverflow.com/questions/10871898/why-cant-i-make-my-div-100-height-if-i-use-an-html5-doctype-how-do-i-get-it-1

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