Chameleon theme in Drupal 6.15 defines color in insufficient manner.

Provided CSS defines color of links but misses background color definition. If user's web browser has incompatible implicit color schema (e.g. white on black), some parts of the web page can be difficult or impossible to read (e.g. dark red on black).

The same problem has mandatory form field marker (asterisk). Also main content misses any color definition.

Solution is to define background color for each class with redefined color and vice versa. The easiest way is to add following line into stylesheet:

html, body {color: black; background-color: white}

Note: I did not checked other Drupal themes but they may be affected too.