I'm following this tutorial on creating buttons with CSS. http://www.secondpicture.com/tutorials/web_design/css_ul_li_horizontal_css_menu.html
The background for the buttons is set in the UL element. What I've noticed is if I remove the height and width attributes of the UL element the background image disappears as if the UL size goes to zero. This doesn't make sense to me from a box model perspective. The children elements( LI ) have set dimensions and should be stretching out the size of the UL accordingly. Can someone explain what is going on?
ul {
list-style-type: none;
background-image: url(navi_bg.png);
height: 80px;
width: 663px;
margin: auto;
}