New design for the @ mention pills

[DantrazTrev]

Is your suggestion related to a problem? Please describe.

The @ mention pills and the room reference look nearly identical to the room reference

There is only one visible distinction of a trailing : that is added if the mention is at the start and is removable.

Describe the solution you'd like.

A redesign for the @ pills that are a bit more distinguishable maybe remove the background and make it bolder?

Describe alternatives you've considered.

Not really sure about the designs so there should be better ones than the suggested

[MadLittleMods]

This may only be a problem with dark theme.

The contrast and differentiation in the light theme seems adequate to me.

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For reference, pills just got a fresh new update: matrix-org/matrix-react-sdk#10417 but I don't think that addressed dark theme colors/contrast.

[weeman1337]

Recent changes did only update the pill logic not the UI.
As far as I know, pills should get a new UI when iterating Element X designs.