I would like to create div like this picture:

So far I created this:
<div style="width: 300px; height: 200px; left:20px; top: 40px;">
<div style="width: 300px; height: 20px; top: 0px; background-color: #76b900; border-radius: 3px; "/>
</div>
How I can add color gradient like the picture. And also how I can add 45 degree angle like the picture?
The idea is to use a pseudo element with the same gradient as the main element, but diagonally across, then rotate it 45 degrees:
Here’s a demo: http://codepen.io/JosephSilber/pen/bFfqn
P.S. Don’t forget vendor prefixes in production…