Expand a div to fill the remaining width

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I want a two-column div layout, where each one can have variable width e.g.

div {
  float: left;
}

.second {
  background: #ccc;
}
<div>Tree</div>
<div class="second">View</div>

I want the ‘view’ div to expand to the whole width available after ‘tree’ div has filled needed space.

Currently, my ‘view’ div is resized to content it contains
It will also be good if both divs take up the whole height.

Not duplicate disclaimer:

  • Expand div to max width when float:left is set
    because there the left one has a fixed width.
  • Help with div – make div fit the remaining width
    because I need two columns both aligned to left

2Best Answer
21

The solution to this is actually very easy, but not at all obvious. You have to trigger something called a “block formatting context” (BFC), which interacts with floats in a specific way.

Just take that second div, remove the float, and give it overflow:hidden instead. Any overflow value other than visible makes the block it’s set on become a BFC. BFCs don’t allow descendant floats to escape them, nor do they allow sibling/ancestor floats to intrude into them. The net effect here is that the floated div will do its thing, then the second div will be an ordinary block, taking up all available width except that occupied by the float.

This should work across all current browsers, though you may have to trigger hasLayout in IE6 and 7. I can’t recall.

Demos:

  • Fixed Left: http://jsfiddle.net/A8zLY/5/
  • Fixed Right: http://jsfiddle.net/A8zLY/2/
div {
  float: left;
}

.second {
  background: #ccc;
  float: none;
  overflow: hidden;
}
<div>Tree</div>
<div class="second">View</div>

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