Tryit Editor v1.8

Source Code:
<!DOCTYPE html> <html> <head> <style> div.container { width:30em; border:1em solid; } div.box { box-sizing:border-box; -moz-box-sizing:border-box; /* Firefox */ width:50%; border:1em solid red; float:left; } </style> </head> <body> <div class="container"> <div class="box">This div occupies the left half.</div> <div class="box">This div occupies the right half.</div> </div> </body> </html>
Result:
W3Schools.com - Try it yourself