Dirke, you can use Safari to find the item to adjust in your CSS. Just do the following:
1) Open Safari
2) Go to Safari Preferences and go to the advanced tab and check the box that says "Show Developer Menu in the Menu Bar".
3) Now you can right click (control click) on any item on the page your on and you'll see an option that says "Inspect Element". You can now see the CSS for every item and can even change the values in the CSS inspector to see what it would look like. It even shows you what line the CSS is on.
4) Then just change those values in the CSS, save, and you should be good.