Why DIVS are collapsing with windows size reduction?

[Authetmup]

I don't know why the text in my HTML page is collapsing inside the menu, here you can find my page in jsfidle.Some of my HTML file:\[code\]<div class="menu"> item 1 item 2 ...</div><div class="content"> text text text</div>\[/code\]Some of my CSS file:\[code\].menu{float: left;padding-top: 100px;width: 20%;position: relative;}.content{float: right;padding-top: 100px;width: 80%;color: #dddddd;position: relative;}\[/code\]Is it a css problem with the width %? Or something else?