I noticed some CSS issues on my site, and narrowed it down to the AddThis styles that are injected into the page... specifically file http://s7.addthis.com/static/r07/widget088.css
The problem that I found is the line #at3wintoolbox a:hover,a:focus{background-color:#3dadfc;text-decoration:none;color:#fff;font-weight:normal;text-shadow:none;opacity:1;filter:alpha(opacity=100);cursor:pointer;}
It looks like someone forgot to put the #at3wintoolbox selector in front of the a:focus style, which is overwriting our local styles.
I can get around this by setting ui_use_css to false and putting in your styles that I have corrected... but would rather use your styles if possible, so I can get any changes or fixed you put into it. Just wanted to share this bug
Thanks