Super and Sub script should have zero line height

This is a problem that can occur when superscript and subscript tags are used with a line height that is larger than the line-height of the paragraph. What it means is that the line gets pushed down causing inconsistency. Have a look at the following example.

Incorrect looking paragraph with a superscript tag

It's a little hard to see in the above image but the superscript tag is causing the line to be pushed down a littler further than all the other lines. If you compare the above picture to the one below, you will see a difference.

Correct looking paragraph with even line heights

This causes an inconsistency that is very noticeable when browsing a website. What we need to do is ensure that the line-height of the sup (superscript) and sub(subscript) tags are less than the paragraphs line-height. The easiest way to do this is to set the line-height of the sup (superscript) and sub (subscript) to zero.

sup, sub { line-height:0; }

Our paragraph lines should now even up with our new sup (superscript) and sub (subscript) CSS declaration.