The site is not giving hashed server seed in advance. You view server seed and hash of server seed only after placing bet so there is no way to know hash of server seed in advance.
Also, code snippet in "Validation" section of each bet is wrong. It's always shows different roll number and who have a little bit understanding of programming know that this line:
Code:
return lucky % 10000;
Please, fix your provably fair ASAP