Its should be working fine ,please recheck you have targeted right ID everytime,if this doesn't solve your problem please provide your code so other's can take a look and find what's wrong.
Try to make sure you have called right event on every position like onMouseUp, onMouseDown.
Recheck your code ,if it doesn't solve it please provide your code so others can take a decent look into your problem.
you can manually find error in css file by check which section is not working Or you can use this website to find syntax error in css file:http://beautifytools.com/css-validator.php
For js you can use
in firefox.