Observed behaviour
a thread's initial message (for a thread that was started from a message in the channel)'s layout box includes the horizontal line below it that separates the initial message with the rest of the thread's messages, thus, when hovering over the message, the h-line also gets highlighted
Reproduction steps
- make a thread from a message
- hover over the initial message in the thread
Build information
Canary Web 2026.1008.22643, Chrome OS (x86), Chrome 152.0.0.0, Locale en-US
Platform
Web