Div collapse after float css

问题:

I have a div called NAV and inside of NAV I have an UL with 5 li which I float to the left, the li's that is but when I do that the NAV collapses. I know this because I put a border around NAV to see if it collapses and it does. Here is the example.

collapsed http://img401.imageshack.us/img401/8867/collapsedze4.png

no collapsed http://img71.imageshack.us/img71/879/nocollapsedkx7.png

as you can see in the first image, the links in the NAV div are floated left and that black border ontop is the actual div called NAV.

in this image you can see how it has top and bottom border and it not collapsed.

here is some of the html and css I used.

alt text http://img301.imageshack.us/img301/5514/codejc8.png

#nav #ulListNavi  a  {
    float: left;
}

回答1:

Add any overflow value other than visible to your container:

div#nav { overflow:auto; }

Then add width to restore the width

div#nav { width: 100%; overflow:auto; }

回答2:

One solution is to add a "clear:both" style to an element after the last floated anchor, for instance:

<div id="nav">
  <ul id="ulListNavi">
    <li><a href="#">Home</a></li>
    <li><a href="#">Search</a></li>
    <li><a href="#">Flowers</a></li>
    <li><a href="#">My Account</a></li>
    <li><a href="#">Contact Us</a></li>
  </ul>
  <div style="clear:both;"></div>
</div>

This causes the containing element to clear all floating elements before closing the containing box.

回答3:

A few other options for clearing floats here:

http://www.quirksmode.org/css/clearing.html

http://www.sitepoint.com/blogs/2005/02/26/simple-clearing-of-floats/

As to the best way of doing it, that's almost a holy war, the purists would freak about the extra div, if you are not fussed by a little extra markup, the addition of the cleared div as suggested by Joshua and AJ will work fine, and is a reliable technique, but there are at least 17 other ways of doing it...

回答4:

add this code after your ul:

<div style="clear: both"></div> 

回答5:

Try floating the containing element to the left too.

回答6:

Don't bother with clearing elements or overflow. Add this:

#nav {
    float: left;
}

When you float the LI's, the #nav no longer "contains" anything so it collapses. But if the #nav is floated also, it contains anything floated inside it, so it expands again.

(Also consider removing the #nav div and just applying the same styles to the UL.)

回答7:

Your problem is because you are floating the <A> elements, but each of them is inside an <LI> element. LIs display as blocks by default, so each <LI> is forcing it's child <A> to begin on a new line.

If you float the <LI>s, I think you'll solve your problem.

#nav #ulListNavi  li  {
    float: left;
}

回答8:

The quickest solution would be to add overflow:hidden to clear the float on the parent element:

#nav{overflow:hidden;}

回答9:

Without changing your HTML:

#nav
{
    width: 100%;
    overflow: auto;
    border: solid 1px red;
}
#ulListNavi
{
    margin: 0;
    padding: 0;
    list-style: none;
}
#nav #ulListNavi li
{
    float: left;
}
#nav #ulListNavi li a
{
    margin-left: 5px;
}

Works in IE8 and FF 3.5