title: sizing DOM elements with HTML & CSS
body: <p>When creating a <code>&lt;header&gt;</code> within a HTML document is there a standard way of setting the size of the <code>&lt;header&gt;</code> tag in CSS?  For example, Stack Overflow's header is set at 31px, and many other sites use values such as 107px or 117px sizes that are not even numbers.  Is there a method behind determining these heights?</p>