窗口大小调整时的CSS topnav对齐问题

I'm having a bit of trouble keeping the topnav on my Web site (if you'll see the link below, the "Home," "Archive," and "About" buttons) aligned with where I'd like to keep it on browser resizing, which is at the right edge of my banner. Originally, I had four buttons and managed to keep everything in order, but things got a little wonky after I dropped one button.I'm having a bit of trouble keeping the topnav