Thanks!

[edit]
Hmmm... I can't seem to find a way to convert my tileset to 256 colors.
Who uses Photoshop? Can someone gimme a tip?

[edit 2]
Whee! I succeeded!
But when I converted it, the colors were srambled, and when I started the game, Jazz looked weird too!

Grrr.. I hate Photoshop. And I hate MSPaint too.
Ya see, I made the tiles and mask with PS, then saved them in 256 colors using MSPaint.
Result: the background color changes slightly and all blocks are totally solid.