I get this too. The button is out of frame, you have to zoom in your browser and go fullscreen to make it appear.
The frame of the game is quite small even in fullscreen, at least in the Web version. This frame is too small to show the full comic. I was able to see the button by zooming in with the browser to 170% and using Itch's fullscreen option. Even with that, in the main game the edges were cut out.