A place for discussion about skinning and design. Before posting questions here you should review the documentation about creating skins.
Reading the docs, it appears that the CSS for this button was originally in stylelayout.css, and then later several CSS files were combined into style.css.
Looking into style.css I am not seeing the addthisbutton section.
So... I am sure I am overlooking something here. Where do I go to modify the position of the addthis button in my skin?
If all else fails you can wrap it in a div in layout.master, put your own class name on the div and use that for positioning. If it already has a div with a class, you can always add the class to your css and apply positioning.
Hope it helps,
Joe