The vertical-align property sets the vertical alignment of an element. Elements with a 'display' value of 'block' ignore the vertical-align property, but their inline children (if any) will inherit the vertical-align value. Tip: if you set the 'display' property to 'table-cell' you may find that vertical-align works in the way you expect (the same goes for applying vertical align on actual table cells). This tutorial on vertical-align is worth reading.
Value
Description
baseline
Align the baseline of the element with the baseline of the parent element. This is default
length
Raises or lower an element by the specified length. Negative values are allowed
%
Raises or lower an element in a percent of the 'line-height' property. Negative values are allowed
sub
Aligns the element as if it was subscript
super
Aligns the element as if it was superscript
top
The top of the element is aligned with the top of the tallest element on the line
text-top
The top of the element is aligned with the top of the parent element's font
middle
The element is placed in the middle of the parent element
bottom
The bottom of the element is aligned with the lowest element on the line
text-bottom
The bottom of the element is aligned with the bottom of the parent element's font
Vertical Align
The vertical-align property sets the vertical alignment of an element. Elements with a 'display' value of 'block' ignore the vertical-align property, but their inline children (if any) will inherit the vertical-align value. Tip: if you set the 'display' property to 'table-cell' you may find that vertical-align works in the way you expect (the same goes for applying vertical align on actual table cells). This tutorial on vertical-align is worth reading.
Themeover CSS Reference
Online CSS References: Vertical Align
Online CSS Tutorials: Vertical Align