[Bug] Left sidebar leaves gab when modal is open

[hhyyrylainen]

Describe the bug When a modal is open the left sidebar and the top bar (both that are sticky) don't position themselves correctly.

To Reproduce Steps to reproduce the behavior:

1. I created a reproduction case based on the WASM sample, repo here: https://github.com/hhyyrylainen/Modal (here's what I changed: https://github.com/hhyyrylainen/Modal/commit/50055e22b5d7fc49232ba98bca3ce0f5ac0e0158)
2. dotnet run in samples/BlazorWebAssembly
3. Open browser to http://localhost:5000/
4. Scroll down a bit so that the "Show Modal" button is visible but the page is scrolled down at least a little bit
5. Click on the "Show Modal" and pay attention to the bottom left. Now close the modal. See how the left side bar jumps around

update: I just tested with chrome, and noticed that this only happens with Firefox. Tested versions: Google Chrome 90.0.4430.72 Mozilla Firefox 87.0

Expected behavior I expect modals opening not messing with the site navigation bar.

Screenshots Modal is open: Then literally the only thing I do is click the modal X to close it (notice all the other changes that happened on the page):

Hosting Model (is this issue happening with a certain hosting model?):

• Blazor WebAssembly

Additional context Happens both with the default and bootstrap themes.

[larsk2009]

Ah the update you mentioned in the issue seems to be why I couldn't reproduce it, I was using chrome. I can see why it happens.

It happens because of this line. Not sure why it only happens in Firefox and if it is a bug in Firefox or by design.

@chrissainty what do you think?

[chrissainty]

This is linked to #315

[chrissainty]

This now appears to be fixed with the changes to the focus trap