Div extends beyond screen

[kellie]

Goodevening!My problem is fairly simply, my div extends beyond the screen.I have this div:\[code\]<div id="button">Button-text</div>\[/code\]My CSS looks like:\[code\]#button { background-color: grey; text-align:center; padding:10px; margin:15px; width:100%;}\[/code\]I could solve it with box-sizing(but that won't work on older browsers), and it have to be responsive. Any solutions?I also have set up a jsfiddle: http://jsfiddle.net/2k9Cd/