For the life of me I can’t figure out how to get a theme to install in Thunderbird (52.9.1 on Windows 10). I open the add-on manager in Thunderbird, click one of the themes, it opens up in Firefox, and when I click add, it gets installed in Firefox, not in Thunderbird.
All of the how-tos I’ve found online are about downloading the xpi and installing it that way, but there is no download button on any of the themes I’ve found on addons.thunderbird.net.
Can anyone tell me what I’m missing?