Shower pan failed - tore out the old pan and about half of the tile (about
three feet up on each wall) - new tile and pan installed by a contractor -
I'm reinstalling the old shower door, and it looks like the width of the
shower sill (where the bottom runner of the shower door goes) is about 1/2
inch wider than where the top rail of the shower door goes. Not sure if it
was like this previously, or if the hardiboard the tile guy used on the
repair would be different from the original crap put in when the house was
built 20+ years ago.

1 - if I just center the bottom rail on the sill, will some extra caulking
at each end of the bottom rail take care of the width problem and prevent
leaks?

2 - I'm assuming that the vertical rails need to be true (straight up and
down) so the door hangs correctly - since the walls aren't square, could I
just shim the vertical rails slightly at the bottom to make sure they're
lined up correctly - guess I'd have to use some additional caulk there, too?

Using a bar of soap standing out in the rain is looking pretty good right
now!

Thanks!