How do I set the height of the header and footer?
I've tried:

@page {
size A4;
@top-left { height: 10pt; }
}

but it doesn't work.

Mong

Looks like my original reply was lost due to server maintenance, so I'll repeat it. The height of the headers/footers depends on the height of the page margin boxes, which can be specified like this:

@page {
    margin-top: 10pt;
    margin-bottom: 20pt
}