DOCTYPE is hosed. Looks like a bug in the JS.
Switch to Blueprint. Get everything layed out on a grid. Things should line up with each other. This takes programming, not design talent.
Use Blueprint typography. You have no discretion in font sizes anymore. Just let it do its thing.
Stop setting background colors. On anything. They aren't your friend. If they were an ice cream flavor, they'd be pralines and dick. If you lay your site out on a grid, you won't need the background colors to distinguish elements.
Work with three colors: black, grey, and an accent color:
* Most things will be black
* Things that aren't important --- like all your timestamps --- are in grey. Look at the header on this comment. Metadata fades into the background.
* For very important things, use an accent color sparingly. Maybe it's the most important comment on the page.
* Count the number of ways in which any two pieces of text differ. Bold vs. not bold: 1 point. Grey vs. black: 1 point. Big vs. little: 1 point. Things should differ by the minimal effective number of points. That means don't set <h2> text in accent red.
Just do those things and, instead of springing for a designer, you can go to 99designs and ask for a $250 logo. That'll be money better spent.
Your colors do nothing to improve the site. Ditch them. Use black, white, grey, and a single accent color of your choice for text only.
What's the deal with the DOCTYPE?