CSS Horizontal Menu: Firefox whitespace bug
So I came across the most baffling bug the other day that locked me up for a good three hours. I thought maybe I’d just put down what I discovered here on the outer reaches of the blogosphere in case anyone else happens to hit that magical combination of Google keywords and a link to this page comes up.
To describe the problem succinctly: when you’re trying to create a horizontal menu using unordered lists (<ul> and inline <li>), for some reason, in Firefox (2 - I don’t know about 3 which just came out last week), if there is any whitespace between a closing </li> tag and the opening <li> tag of the next item, that whitespace actually displays. At first it looks like a margin spacing issue, but after some tests it’s clearly not. In fact, what baffles me is that ANY text between the closing </li> and the opening <li>, that text actually gets displayed inline! Which makes no sense, because I didn’t think that the <ul> element could have a text node as a direct child. Apparently it can, in Firefox at any rate.
The solution, as I have discovered is to set your <ul>’s display attribute to “table”. I don’t believe IE7 and certainly not IE6 understand display:table, so this is a non-IE fix, but then again, IE wasn’t exhibiting the whitespace behaviour. Here’s some sample code.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Untitled Document</title>
<style type="text/css">
* { margin:0; padding:0; }
ul {
list-style-type:none;
list-style-position:inside;
margin:0px; padding:0px;
display:table; /* This is used for firefox */
/* to avoid the horizontal whitespace bug */
}
li {
border:1px solid black;
display:inline;
margin:0px; padding:0px;
border-collapse:collapse;
}
a {
}
</style>
</head>
<body>
<ul>
<li><a href="#">Line 1</a></li>
<li><a href="#">Line 2</a></li>
<li><a href="#">Line 3</a></li>
</ul>
<p>Other stuff....</p>
</body>
</html>