css question

I know. I will fix it in about an hour when I get home.

As usual it is actually IE that is getting it wrong. The border is on #wrap and the content inside it is floated. You therefore have to clear the floats to get #wrap to wrap around the floated content. Thats what all those clearer divs you see in PunBB do.

Try

#wrap:after {
    content: "";
    display: block;
    font-size: 0;
    height: 0;
    line-height: 0.0;
    overflow:hidden;
    visibility: hidden;
    clear: both;
    }