I came across what I think are a couple issues in the CSS framework.  In the Button section:

1. .ui-button-text-icon .ui-icon-primary, .ui-button-text-icons .ui-icon-primary, .ui-button-icons-only .ui-icon-primary { left: .5em; }

.ui-icon-primary doesn't exist and should be changed to .ui-button-icon-primary (corresponding to .ui-button-icon-secondary).  the icon will then be correctly spaced from the left edge.

This next one isn't so much a bug, but if you are trying to have consistent button sizes across all widgets, you'll want to comment out the padding and line-height parts of the dialog buttonpane CSS (width, overflow, and cursor I think are redundant, too):

1. .ui-dialog .ui-dialog-buttonpane button { float: right; margin: .5em .4em .5em 0; cursor: pointer; padding: .2em .6em .3em .6em; line-height: 1.4em; width:auto; overflow:visible; }