I sent these instructions to uglyskunk, but he couldn't get it to work for him, maybe somebody else can confirm it works or can spot if I made a mistake transcribing or has some advice for uglyskunk:
This should allow you to change the colors for potential if you are using Firefox.
First you need to locate the chrome directory under your Firefox profile. Open Windows Explorer and type %APPDATA% in the Address bar. Then drill into the Mozilla directory and then the Firefox directory and then the Profiles directory. Next will be a directory with a random name followed by 'default'. Drill into that one. From there you will find the chrome directory.
Copy the existing userContent-example.css file and rename the result userContent.css. Open the userContent.css file in Notepad and add the following to the end:
@-moz-document url-prefix(http://www.whatifsports.com/hd/) {
.potential_low {
color: #FF00FF !important;
}
.potential_high {
color: #FFFF00 !important;
}
}
Save and close Notepad. Now restart Firefox. (You have to be sure Firefox closes, use File->Exit or Ctrl-Q.) You should see low potential as purple and high potential as yellow now.