Unused CSS is a one of the issues most web applications suffer when it comes to performance and page load time.
Mentioning this is trivial as no one seems to notice this while using default JQuery show and hide methods to show or hide an element on a page. As you might have noticed this before when you use
hide(), the element gets a
display:none; style. The problem is when you use
show() to show the element again and here is when you see
display:block; is added to element styles.