If I may, why not Firefox? Been running flawlessly for me on a wide variety of distros. Including Pop!_OS.
To be fair, Vivaldi is a good browser but the Chromium base is a difficult pill for me.
Understood! Would you feel up to telling us what customisation you applied and what you particularly like about the mail?
If you don't feel like it, forgive me and ignore this message.
I've changed V-logo to burger and switched menu item to the right. I've craeated my own theme for Sweet that I use in @gnome (https://www.gnome-look.org/p/1253385) and I've hidden most of the panels. I've changed 1Password logo to be monochrome in the toolbar. 👍
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