CSS: wrapper background does not extend to all divs contained therein - html

Question

I have the following html:
<div class="wrapper">
<h1>Ipods</h1>
<div class="main-topright-bottom">
<h1>Related Products</h1>
<div>Check items to add to the cart or select all.</div>
<div class="relatedproduct">
<div class="relatedproductimage">
<img src="https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcR-YiokcA1U38PFCbIYklGbbqu-4E7gj6p-c4txmJjZxblroYu40A" />
</div>
<div class="relatedproducttext">
<div class="relatedproductheading">A red ipod nano.</div>
<div class="price">$140.00</div>
<div class="addtowishlist">Add to Wishlist</div>
</div>
</div>
<div class="relatedproduct">
<div class="relatedproductimage">
<img src="https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcR-YiokcA1U38PFCbIYklGbbqu-4E7gj6p-c4txmJjZxblroYu40A" />
</div>
<div class="relatedproducttext">
<div class="relatedproductheading">A blue ipod nano.</div>
<div class="price">$140.00</div>
<div class="addtowishlist">Add to Wishlist</div>
</div>
</div>
</div>
</div>
and css:
.wrapper { background: blue; }
.relatedproduct { clear: both; }
.relatedproductimage { float: left; }
.relatedproducttext { float: left; }
I want to know how come the blue background does not extend to the bottom div.
What am I doin wrong?
http://jsfiddle.net/johngoche99/C9NKP/2/
Thanks.

Answer 1

Floats aren't contained by default. You make it do this by floating the wrapper too, or giving it an overflow property.
.wrapper {
overflow: hidden;
}
jsfiddle demo
Read http://colinaarts.com/articles/float-containment/ for another (better) alternative if you don't want to hide overflow as a side-effect.
More information at https://developer.mozilla.org/en-US/docs/Web/CSS/Block_formatting_context

Answer 2

change
.wrapper { background: blue; }
To
.wrapper { background: blue;overflow:hidden;}