<style>
html, body {margin:0; padding:0; height:100%; width:100%; background-color:#fff;}
.conteiner {width:600px; background-color:#000; margin:0; padding:0; position:relative}
.div1 {width:300px; background-color:#ff0000; margin:0; padding:0; float:left;}
.div2 {width:300px; background-color:#00CCCC; margin:0; padding:0; float:left;}
</style>

prova e poi fammi sapere