In my opinion, this is the best cross-browser method of clearing floated elements in a container. Remember to add .clear-fix{zoom:1;} to an IE specific stylesheet, otherwise IE 7 will complain.
.clear-fix:after {
clear: both;
content: '.';
display: block;
line-height: 0;
height: 0;
visibility: hidden;
}
.clear-fix {
zoom: 1;
}