Hi everyone,
I've just released version 1.5.2 of this extension, which attempts to make it easy to choose custom colors for the extension!
By default, messages that you send now use the forum's primary background color and text color, and messages that you receive use a green background color with a black text color:

To change this, open your forum's administrator page, open the Private Messages panel, check the "Enable custom colors" checkbox, choose some custom colors, and click "Save Changes":

This is a breaking change for two reasons:
- The default colors have changed.
- The default CSS selectors have changed slightly, so if you're overriding the colors via CSS, you might need to rework your CSS selectors, although I hope not!
My apologies for introducing a breaking change. I try not to do this often, but in this case, I felt it was worth it.
Another big improvement is that emails are now HTML, so they look a lot better. Thank you to @erictfbat for this change! :D
Emails should now look something like this, although this can vary a lot between different email clients:

I've tested the email functionality with Outlook but haven't been able to test on Gmail, as I don't have a Gmail account. If someone upgrades and tests with Gmail, please let me know how the emails look!
I'd be grateful for any brave testers to update to the latest version and let me know how it goes 🙂
I'm also happy to add additional color customization options, if people want to be able to customize other parts of the extension.