Why do my image background disappear on float: left?
I want to create a navbar with images on each end to make it purty.
So, I created the HTML and CSS below and it worked great. My menu items are in a ul/li list.
When I style the list to put the items all on one line, the images on the ends disappear. What's up with that? How do I fix it?
The culprit is float: left; below.
--- test.html ---
<html>
<head>
<link rel="stylesheet" href="test.css" type="text/css">
</head>
<body>
<div id="container">
<div id="header-usernav" class="span-6 last large">
<div id="header-usernav-leftside"><div id="header-usernav-rightside">
<ul>
<li>Register</li>
<li>Signin</li>
<li>Signout</li>
</ul>
</div></div>
</div>
</div>
</body>
</html>
--- test.CSS ---
#container #header-usernav {
background: url('http://www.webcredible.co.uk/i/bg-i-resources.gif'开发者_如何学JAVA);
height: 28px;
background-repeat: repeat;
}
#container #header-usernav-leftside {
background: url('http://www.webcredible.co.uk/i/nav-l-h.gif');
background-position: top left;
background-repeat: no-repeat;
}
#container #header-usernav-rightside {
background: url('http://www.webcredible.co.uk/i/nav-r-h.gif');
background-position: top right;
background-repeat: no-repeat;
}
#container #header-usernav ul {
list-style: none;
padding: 0;
margin: 0;
margin-left: 10px;
}
#container #header-usernav li {
float: left;
padding: 0;
margin: 0 0.2em;
}
The images are different so the html/css can be copied pasted to test it.
What's the deal? What am I doing wrong?
I'd recommend adding overflow:hidden; (and zoom: 1; to maintain cross browser compatability for IE6) to the container div rather than adding a clearing div. Clear adds bloat to your source code.
#container #header-usernav ul {
list-style: none;
padding: 0;
margin: 0;
margin-left: 10px;
overflow: hidden;
zoom: 1;
height: 28px; /* This is needed to ensure that the height of the rounded corners matches up with the rest of the bg.
}
With only floated children, your outter container will return a height of 0px. As such, you can place the following immediately after the floated element(s):
<div class="clear"></div>
And add the following rules:
.clear { clear:both; }
For example:
<div id="container">
<div id="header-usernav" class="span-6 last large">
<div id="header-usernav-leftside">
<div id="header-usernav-rightside">
<ul>
<li>Register</li>
<li>Signin</li>
<li>Signout</li>
</ul>
<div class="clear"></div>
</div>
</div>
</div>
</div>
It's happening because your divs have no height. You can add an empty div with clear: both immediately after your UL. Or you can add these styles to UL
width: 100%;
overflow: auto;
See this for an explanation.
Add a height: 28px; to your ul in your css. Jonathan and Chetan have already given a very good explanation of why this works, but to reiterate, parents of floated elements are not affected by the height of their floated children.
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