For some time I borrowed @ChrisBeach’s CSS snippet, so I converted it into a theme component, find the result here:
What it does
It changes the appearance of the page when a personal message is being read:
- the head banner color (with a gradient),
- the font color,
- the background color,
- the title color,
- by adding some text after reply.
All these changes are optional and can be toggled with their on/off setting. The main «personal messages» color can also be changed with a setting. To tweak the different colors, edit the top part of the CSS file.