Add horizontal scrollbars for messages that overflow - Keep chat window width clean when someone sends an unintelligible message

Add horizontal scrollbars for messages that overflow. This keeps the chat window width clean when someone sends an unintelligible message

Reproduction

In chatroom if send a message with this KaTeX:

$$-------------------------------------------------------------------$$

Before	After

In this example, I only used few characters, but would be worse with 4096 char - in rooms...