Ever wonder how many of those CSS rules your page isn't using?
The Audit tab in Chrome Developer Tools will analyze the page and tell you which selectors are not used.
Large amounts of unused CSS are particularly common when using a modern UI framework like Bootstrap or Foundation. The report may show that over 90% don't apply.
By the same token, non-Webkit browser prefix properties show up in this list because they don't get used when Chrome renders the page.