CRTs with snes controllers sounds fantastic.
I did have trouble centering the image on screen due to the frame being wide with borders. First I set my desktop resolution to 320x224 but when I went full screen this produced:
Lovely to see it was pixel perfect but I lost a third of the screen to the border. I saw in the page source that the embedded app has dimensions of 796x448 (398x224 x2) so I added a modeline in CRTEmudriver and set my resolution to 400x224 (it rejected 398 for some reason). This gave me a full screen squished to the right side. I couldn't adjust the monitor above anywhere near centre, so I moved to a different cab and got it close-ish by tweaking the horizontal pots as much as I could.
I don't suppose the game area could be changed to a 4:3 resolution? Or maybe a downloadable version would make life easier?