I have a container "div" with within 3 columns:
why the columns do not extend in vertical the container "div",
that is exactly that contains them
<html>
<head>
<style type="text/css">
body {
color: #000;
background-color: #99CCFF;
}
#contenitore
{
background:yellow;
color: #000;
border:10px solid green;
}
#colonna1 {
float: left;
width: 20%;
background:blue;
color: #000;
}
#colonna2 {
float: left;
width: 60%;
background:silver;
color: #000;
}
#colonna3 {
float: left;
width: 20%;
background:red;
color: #000;
}
</style>
</head>
<body>
<!---------------------------------------->
<div id="contenitore">
<!-- 1 -->
<div id="colonna1">
<ul>
<li>aaaaa</li>
<li>aaaaa</li>
<li>aaaaa</li>
<li>aaaaa</li>
<li>aaaaa</li>
<li>aaaaa</li>
</ul>
<ul>
<li>aaaaa</li>
<li>aaaaa</li>
<li>aaaaa</li>
<li>aaaaa</li>
<li>aaaaa</li>
<li>aaaaa</li>
</ul>
</div>
<!-- fine 1 -->
<!-- 2 -->
<div id="colonna2">
<ul>
<li>aaaaa</li>
<li>aaaaa</li>
<li>aaaaa</li>
<li>aaaaa</li>
<li>aaaaa</li>
<li>aaaaa</li>
</ul>
</div>
<!-- fine 2 -->
<!-- 3 -->
<div id="colonna3">
<ul>
<li>aaaaa</li>
<li>aaaaa</li>
</ul>
</div>
<!-- fine 3 -->
</div>
<!---------------------------------------->
</body>
</html>
