Mmm kay, here's the latest WIP:
This is an attempt assuming a 100px grid. I've moved the stair railings further towards the edges of the causeway to make it work sensibly as a 10-foot-wide staircase rather than a 5-foot-wide staircase chopped in two by the grid. All the side chambers have half-squares around their borders, but oh well. Maybe those can be filled with props or something.
I used the Cunning Cartographer's water trick, and it's working reasonably well here.
As usual, the big problem is depth. I'm not satisfied with the sense of depth. The water looks like its simultaneously level with the upper floor and the lower floor, which is of course impossible. Likewise, the pillars in the pool should feel like they extend upwards, but at the moment they look more like big stone lilypads, level with the water.
It's also ... really, really rectilinear. That comes from the design of the actual real-world temple, of course, but I do get tired of 100% straight surfaces. Maybe I could swap in some round columns or something.
Meh! Gotta let it simmer a bit.
 Barring magic or a really oddly shaped aquarium.