percent width

Percent is a measurement unit relative to the containing block. It's great for images: here we make an image that is always 50% the width of its container. Try shrinking down the page to see what happens!

article img {
  float: right;
  width: 50%;
<article class="clearfix"> an image

You could even use min-width and max-width to limit how big or small the image can get!


percent width layout

You can use percent for layout, but this can require more work. In this example, the nav content starts to wrap in a displeasing way when the window is too narrow. It comes down to what works for your content.

nav {
  float: left;
  width: 25%;
section {
  margin-left: 25%;
<div class="container">

When this layout is too narrow, the nav gets squished. Worse, you can't use min-width on the nav to fix it, because the right column wouldn't respect it.


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