Can't close side panel in Google Voice

[BGM]

I like to run Google Voice in Vivaldi (or Rambox). How can I hide the right-panel? It takes up a lot of room, and there doesn't seem to be any toggle.

Anybody know how to get that panel to toggle closed?  I can't find any control to do that. 
It didn't use to be there; one day it appeared and now I can't close it.  And I can't seem to google up any solution.

If I run the browser in full screen, it's not so bad, but if I run it in a smaller window, I can't hardly see the typing area it is so small, the space is hogged up by the side panel.

Ad blocker is off.  Javascript is enabled.

Can't close side panel in Google Voice

[Deozaan]

Which side panel are you talking about? Got any screenshots to show what you mean?

[BGM]

Deozaan - okay, I added a screenshot.

What is supposed to happen is that when the browser window shrinks, the panel should turn off.  When I use Rambox, this never happens.  When I use Vivaldi, it does turn off when the window gets shrunk.  But when I use Waterfox, the panel doesn't even appear - and it never used to appear on the other applications.  I'm trying to turn it off because I never use it and it takes up too much room.

[Deozaan]

As you've stated, it uses a responsive design so if you make the width of your browser a little smaller, it will normally go away.

Another possible workaround is to block the side panel element with an ad blocker or just remove it (until the page is reloaded/refreshed) by right-clicking the page and clicking the option that should be something like "Inspect Element" and selecting it and deleting it. Look for the <gv-call-sidebar> element. But I'm not sure if that will also have the side-effect of disabling your ability to make or receive phone calls from the website.