Too wide

I made my game 1280 x 720. I used this because it is a 16:9 ratio resolution.

I tried uploading my game to the Scirra arcade but I got the following message:

"Sorry :( This game is too wide. Max width is 800px"

If I try to change the window size then the display is zoomed in too much. How to I shrink the entire game but keep the aspect ratio the same so that it is not zoomed in too much?

Protip: you could use the "Pode HTML Pack" plugin (link) and have it render your current game project within a project that has the proper width and scale it down (this should be possible, however you should expect performance drops).

you could also look into the layout scale if needed