Superscripts & Subscripts

Big Symbol (like \sum_{i=0}^n) CSS work: http://jsfiddle.net/YfYmk/1/

The baseline of an 'inline-block' is the baseline of its last line box in the normal flow, unless it has either no in-flow line boxes or if its 'overflow' property has a computed value other than 'visible', in which case the baseline is the bottom margin edge.

CSS 2.1, Section 10 Visual formatting model details