Dexmaster / Custom Feedly Styles (+ Always Show Left Menu)

Hi Dexmaster. mark_all_fix originated in the past, at my request, thank you for that.
It would be possible to make its presentation to behave a little differently? Very fine for me it's a big button smaller than the original, and it is always at the bottom of the browser window, but in some occasions upset that is displayed at the same place every time, and in some cases that were not good, as shown in the preview :

Giant Mark all as read fixed
Giant Mark all as read original

Modified giant button takes up less space so that it's at the bottom, but otherwise, it would probably well to behave like the original button.
Yes, I know you there then added only another script recommended by me, but if you were his behavior, he managed to tweak a little bit, that would be great.. :-)

Big thanks, F.