Can I put a SPAN inside a DIV?

I’m trying to build a site where a series of icons are displayed inside a white box, with a footer below them, but whenever i make my browser window thinner, the icons which are contained within a DIV cllapse down the page so they still fit, but the background DIV they are in doesn’t expand with them. What am I doing wrong?

HTML Code:
<div class=“container”>
<!—- begin icons—>
<span class=“bookmark”><a href= ‘http://google.com’ target=‘_blank’>
<img src=‘images/icon.png’ border=0 id=‘ico_15’ width=‘160’ height=‘145’><br>google.com</a></span>
<span class=“bookmark”><a href= ‘http://google.com’ target=‘_blank’>
<img src=‘images/icon.png’ border=0 id=‘ico_15’ width=‘160’ height=‘145’><br>google.com</a></span>
<span class=“bookmark”><a href= ‘http://google.com’ target=‘_blank’>
<img src=‘images/icon.png’ border=0 id=‘ico_15’ width=‘160’ height=‘145’><br>google.com</a></span>
</div>

CSS Code:
.container {
min-height: 300px;
background-color: #FFFFFF;
text-align: center;
}

.bookmark {
color: #00A4D5;
font-size: 12px;
left: 5%;
right: 5%;
float: left;
}

This is my first foray into DIV and CSS so I’m probably doing something stupid…