Style scores and seeds seen as tiles

Add color and chaos to the scores and seeds-seen boxes -- though I may
make an exception for zero later, at the moment it's too amusing.
undo holdover bad code from previous pull request. 

maybe this makes the merge clean and easy?  I hope?
less redundant CSS for backgrounds
sprite, for testing
Merge branch 'master' of https://github.com/alexfink/alexfink.github.io
forgot the sevens and elevens
use sprite for tile overlays
now primes up to 367
generate styling for higher primes
non-integral sizes seem to bother css background-position in some browsers
fix merge conflict
Merge branch 'VynceMontgomery-score-amusement'
Merge pull request #3 from alexfink/master

Sync alex's work to Vynce's fork