While learning CSS, the one thing I kept (and keep) messing up was the ability to position elements correctly.  I found I had a hard time getting the correct way to use position absolute and relative.  The trick that I was taught was when you use position: absolute to define your specific co-ordinates (ie top: 10, left: 20), you need to make sure that element’s parent CSS class (ie a container class or ul tag) is defined with the position: relative) and then you’ll find you can position the children element much easier.

Good luck with it!