[html] How to split page into 4 equal parts?

Some good answers here but just adding an approach that won't be affected by borders and padding:

<style type="text/css">
html, body{width: 100%; height: 100%; padding: 0; margin: 0}
div{position: absolute; padding: 1em; border: 1px solid #000}
#nw{background: #f09; top: 0; left: 0; right: 50%; bottom: 50%}
#ne{background: #f90; top: 0; left: 50%; right: 0; bottom: 50%}
#sw{background: #009; top: 50%; left: 0; right: 50%; bottom: 0}
#se{background: #090; top: 50%; left: 50%; right: 0; bottom: 0}
</style>

<div id="nw">test</div>
<div id="ne">test</div>
<div id="sw">test</div>
<div id="se">test</div>