Channel name is not shown properly with long topics in new UX

Description:

In RC 7.6.0 with the new UX on small screens with long topics the channel name gets cut too early in the channel top bar. Without visual reminder of the channel name people reply into wrong channel more easily.

Long topics are often caused by the need to include lots of wiki links etc. in them, so this issue happens easily on older environments where the users are used to do this.

Steps to reproduce:

1. Make a channel with very long topic
2. Make RC window smaller

Expected behavior:

Actual behavior:

Server Setup Information:

• Version of Rocket.Chat Server: 7.6.0
• License Type: Premium
• Number of Users: 500+
• Operating System: RHEL8
• Deployment Method: docker
• Number of Running Instances: 4
• DB Replicaset Oplog: Yes
• NodeJS Version: 22.13.1
• MongoDB Version: 6.0

Client Setup Information

• Desktop App or Browser Version: Any

Additional context

As a workaround we applied this custom CSS:

div.rcx-box.rcx-box--full.rcx-css-1banssg.rcx-css-f2vsf1 {
   flex-shrink: 0 !important;
}

Design comment:
The new design is bit cumbersome regarding that topic length and visibility too, but I suppose announcement bar can be used as a base for quick links now. So it may be better this way in the long run.

Reproduce the issue in Rocket.Chat 7.6.0 by opening a channel with a long topic and narrowing the window. Inspect the channel top bar and its layout behavior, then verify that the channel name remains sufficiently visible on small screens without breaking topic display.