This style will stretch the "New Tab" button to it's maximum available width. Great if that empty space in the tab bar has been bothering you all this time.

I did not find, or initially code the CSS for it. Greg K. Nicholson of AMO did, though, this is just the userstyles.org modification of his CSS. Thought I'd take his addon "Big New Tab button and check it out. It occured to me, it's just some CSS wrapped up to go, figured it'd work just as well in Stylish.

And guess what? It did! His code has been dissected and torn down to the absolute minimum required for this to work. Decomment min-width if you'd really like to keep it a "Big" button.