One of the common gripes that web designers have is the limited selection of typefaces they can use. Although there are many different font-replacement methods that exist, there is no perfect way. That is when a decision needs to be made. Do you focus on design or search engine/user-friendliness?
Color is a crucial element to a website. But color can also be the downfall to a website. Where there is too much or too little color, the site looks flat (or too vibrant) and the user-friendliness of the site is lowered.
Internet Explorer was probably created because Microsoft hates developers, and here is yet another problem to prove it. IE6 and IE7 (thankfully not IE8) have problems when it comes to rendering overlapping absolutely positioned elements. Learn how to fix the bug that causes overlapping with absolutely positioned elements and z-indexes.