Plain bars for free performance

Hi,

While focused, this site uses too much CPU. Chromium's timeline functionality shows that it has to repaint all the bars few times a second, which takes around 40% of my old CPU. However, if I disable striped+active progressbars, it takes virtually no CPU cycles and only updates on refresh (which is great and doesn't use that much CPU).

In this PR I disable striped bars. While they don't look so fancy, they're still pretty cool :D.