Css3 transitions don't start for the first time in Firefox 4

Question

I am experimenting with some css3 transitions. I put together a quick slider test and it works well in the webkit family. In Firefox 4, when you click the left link, the slider is supposed to move to the left, however, the css transition does not happen until you click the link. I put the demo on jsfiddle - http://jsfiddle.net/mrleroylee/ctY68/

Is this the result of something in my code or is it a mistake?

Answer 1

Set left: 0 in your styles for ul ; which made it work on the fiddle for me: http://jsfiddle.net/ctY68/4/

It seems that Gecko is not considering your first transition change style because there was no initial value.