Yes, none of the suggested tags seem to remove the border or centre the slideshow, it remains black and aligned left whatever.
Slickr Flickr uses no CSS at all when you use the Galleria: and the styling is controlled by the Galleria ‘theme’ and any CSS that your WordPress theme imposes
Galleria has several themes: classic (the default), fullscreen, folio, twelve, miniml or azur.
To customize the galleria styling you have two options:
1) add overrides to the various elements in your style.css to get the desired background color and alignment
2) copy the ‘classic’ folder and create a galleria themes folder OUTSIDE the plugin root, then rename the folder to ‘classic-white’, rename the galleria.classic.css file to galleria.classic-white.css, and edit this file to change the background color and alignment. Finally, in the Slickr Flickr Admin Galleria section set the theme to be “classic-white”.
I have it on my TODO list to go for the second option, but up until now I have just used first option, as it a bit less work
