proton-ambiance is a ProtonMail Themes aimed to imitate the look and feel of the GTK Ambiance Theme. Looks best on Ubuntu, especially when paired with Firefox.
- Pick the theme you like from the themes folder in the repository.
- Select the theme and select the code view.
- Select everything, make sure you have absolutely everything selected, and copy the code.
- On ProtonMail's website, click on Settings, then click the Appearance tab.
- Paste the code under the Custom Theme section and press save.
- Finally, make sure to refresh the page so all the changes can take effect.