div with no content have a width/height
.shape-round{
width: 40px;
min-height: 40px;
background: #FF0000;
border-radius: 50%;
}
<! --- While using CSS, to style the div (content-less), the min-height property must be
set to "n"px to make the div visible (works with webkits and chrome, while not sure if this
trick will work on IE6 and lower) --->