1. Under draw_basic is where the outlines are drawn (lines 190-191 for example). Just change them to match the size of the actual bars (should be 100x12), and add 1 to the x and y position.
2. Pretty much any time you see (0...@psize).each, replace with (1...@psize)each. You will have to change a few things in the create_positions methods too to keep it centered.