initial floating gallery configuration
much simplified css
 centered plot and code with a table
better looking code, everything is left-aligned
 titles and h1 with the example name
 gridplots now compute and set width and height based on the sum of the width's and heights of all the constituent plots
 more rome for the gridplot toolbar,  the plots no longer overlap the button (which was causing them to intercept clicks)
per example classnames for the css, this allows setting specifc heights to avoid the flash of content
 tightened up vertical separation
 merged in gallery_refactor