This plugin provide an easy and elegant solution to add and display your mathematical fourmula.
When the generated images are transparent, they are fit to any background. Otherwise, you need to use a LaTeX image service which supports custom background and foreground color.
http://l.wordpress.com/LaTeX.php?bg=ffffff&fg=000000&LaTeX= is a good candidate. The bg parameter defines background color and fg parameter defines foreground color, you can customize them to any RGB colors.