Different outputs in Workspaces

I’m not sure if that’s the correct place for the following, so please move it, if not.

Depending on using devtools to increase the size of the output window or not, I get different results in workspaces.
The upper part of the page looks perfect if I use devtools:

Not using devtools there is a black gap on the right side:

With the lower part of the page it’s the other way round:
Using devtools, a row of textfields is pushed to the left side:

Without devtools it looks more or less how I want it:

I have the feeling I maybe use workspaces not the way it’s meant to be used?
What’s your opinion to this?