Well, technically you need a degree of some sort, but if you want to be good you need to know the basics and some advanced. knowing how to do stuff like properly use -web-kit-transitions and hover attributes, also stuff like proper use of the "onMouseove r" or "onMouseout "
If you know all about html/css tags, their working and how they are supported in different browser. Also if somebody ask you to create a design you quickly break it into divisions and apply css to it then you can call yourself as a expertise.
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