How to get a fixed (small) size page?

Working on a plugin for an app, I need a fixed size html dialog for user input.

I set the project width to 500px. One blok, 2 columns. Form in first, image in second.
I can see everything alright if the browser page is more than 990px wide.
As soon as I try to narrow it to fit, the whole thing disappears.
What am I missing ?
Or can it be done with Blocs ?

Sounds like your content is only visible in the desktop. Check the visibility.

Did you succeed in doing this ?

No, but then again I didn’t try.

When I did try the form is stacked over the image, so I think maybe some bootstrap/blocsapp magic is at work.

I think perhaps fixing sizes would help. Trickier than I imagined.