h(x) = 398a87c004951654b7cce89b3d0e59775c2bee34411f7eb146a23cdabdd67ab6
author: unknown
h(x) looks like a cryptographic hash, and refreshing the page shows it changes every 5s. We find that the SHA256 hash of the unix time (floored by 5 seconds) gives us the same hash. Thus the answer is the current unix time (and values within ± a minute are accepted).