I've done this myself as well, and for similar reason (not wanting to install additional add-ons). Mine is: https://github.com/nuchi/gmail-inbox-high-contrast-

I've done this myself as well, and for similar reason (not wanting to install additional add-ons). Mine is: https://github.com/nuchi/gmail-inbox-high-contrast-restoration https://github.com/nuchi/gmail-inbox-high-contrast-restorati... It restores the appearance of Gmail from before the recent (~2 years ago) layout change.