Font color of MessageTimestamp different between main timeline and right panel (TimelineCard, ThreadView, ThreadPanel)

[luixxiul]

Steps to reproduce

1. Compare timestamp font color on the main timeline and the right panel

Outcome

What did you expect?

The color should be consistent.

What happened instead?

The font color of the timestamp on right panel (ThreadsList, ThreadView, and TimelineCard) has been specified on this line based on #19669.

Main timeline	Right panel
↑ Inherited from the default value	↑ Specified on on this line

Probably should the default color be replaced?

Operating system

Debian

Browser information

Firefox ESR 91

URL for webapp

app.element.io

Application version

No response

Homeserver

No response

Will you send logs?

No

[turt2live]

Let's converge on the colour from the main timeline.

[luixxiul]

matrix-org/matrix-react-sdk#10016 seems to have fixed the issue. There should be a percy test about possible color change due to cascading.

The problem is that percy would complain every time you run the test due to the change of timestamp string. I'm adding a test which checks a CSS variable of the timestamp color instead.