I don't think the lava bubbles work so great as a border. It looks less sideview now, but the lava looks like a bubbling mass of stuff instead of being a level below in elevation. What I had in mind was a simpler fix like this:
I like your fix, but I also like having full borders with perspective in spite of me wanting to keep things simple. The edge borders need redrawn from the ground up, to be narrower, and the bottom bubbles should be slightly more visible imo. All I did was rotate the bubbles, and edit them very slightly. To me though, these tiles shine in motion. I seriously think it might be the best animation I've done in a long time, if not ever. There's a subtle glow effect on the original bubbles, and it just looks so cool. /suckingmyowndick.