I don't do a lot of front-end stuff, but for this, you need a scripting language as the width's will vary depending on the tables' width. HTML alone cannot do this for you.
For example, for JQuery, try something of this sort:
var thewidth = $('#MyTable').width();
//Then add width to header and footer
//Then you can apply this width to the header and footer
Try something along those lines. JQuery really makes work easier
. Less code, more logic packed in.