How to auto adjust the <div> height according to content in it?

I have a <div> which needs to be auto adjusted according to the content in it. How can I do this? Right now my content is coming out of the <div>

The class I have used for the div is as follows

box-centerside  {
background:url("../images/greybox-center-bg1.jpg") repeat-x scroll center top transparent;
float:left;
height:100px;
width:260px;
}

Just write "min-height: XXX;" And "overflow: hidden;" & you will be out of this problem Like this

min-height: 100px;
overflow: hidden;

Try with the following mark-up instead of directly specifying height:

.box-centerside {
  background: url("../images/greybox-center-bg1.jpg") repeat-x scroll center top transparent;
  float: left;
  min-height: 100px;
  width: 260px;
}

<div class="box-centerside">
  This is sample content<br>
  This is sample content<br>
  This is sample content<br>
  This is sample content<br>
  This is sample content<br>
  This is sample content<br>
  This is sample content<br>
  This is sample content<br>
  This is sample content<br>
  This is sample content<br>
  This is sample content<br>
  This is sample content<br>
</div>

Just write:

min-height: xxx;
overflow: hidden;

then div will automatically take the height of the content.