Hi,
The new messages style means I can no longer add staff colour to my own posts in messages as they are already highlighted in blue which is --tertiary-very-low colour.
Being able to highlight your own messages is useful. Lets say two users are having a heated argument in a PM and a flag arises and a moderator steps in and reminds them of the rules I think staff should be able to highlight their reply.
This is our staff colour as seen in image above