Indicates the width of the slider. Initially, the slider has the 100% of witdh of html tag that contains it!
Suppose you have two slider on the same page, and you want one takes the width of the parent html tag and the other one takes just 70% of parent's width. A simple way to achieve this is to pass the measure in '%'. Another way to get it is to pass the width in 'px'.
Note that the height of the slider is automatically set depending on the size of the images!
