The file has the first sqrt(1000) primes hardcoded in it.
If you wanted to find the first 100.000 prime numbers, you'd need to add all the prime numbers up to 313 in the css file.
You should look more closely: it doesn't. The CSS selectors are for 2, 3, 4, 5, 6, 7, 8, 9, ..., 32. The most you can say is that it has sqrt(1000) == 32 hardcoded into it, but there are no primes.
Ok, I get it. However, you still need to modify the source code to accomodate for larger inputs.