Question: I've got a list with list-style-none which needs to be able to add new items to itself via Ajax and have the background expand appropriately when it does. Adding via Ajax is easy, but every solution I try for the background fails me. I don't know if it's even possible; is it? I'm using a grid like this one:

<http://jqueryui.com/demos/sortable/#display-grid>

Both WebKit and Firebug are showing me skinny, empty bars when I hover over the enclosing divs and/or the enclosing ul tag. It appears that the minute you set a list loose with list-style-none and float:wherever, you give up control over its background. But that can't be right.

Answer: 
This is something I've run into a number of times. The problem is that floated elements aren't part of the normal box model, so they don't cause their parent elements to expand **unless** their parent elements are also floated. So if possible, float the ul or containing div.

Edit:
See [quirksmode](http://www.quirksmode.org/css/clearing.html) for another css-only workaround.
For dealing with the float element, maybe you should know it's characteristic, gotcha, and how to deal with it.
See the links below, it also have demo, so you can understand the concept:

1. <http://www.smashingmagazine.com/2009/10/19/the-mystery-of-css-float-property/>
2. <http://www.smashingmagazine.com/2007/05/01/css-float-theory-things-you-should-know/>
3. <http://aloestudios.com/2009/12/goodbye-overflow-clearing-hack/>
and
<http://aloestudios.com/misc/overflow/>