Some dark theme related UI issues

[Jerome-Herbinet]

Describe the bug
Some UI's parts don't fit Nextcloud dark theme.

To Reproduce
Steps to reproduce the behavior:

1. Set your user with dark theme
2. Go to BBB connector
3. Notice the issues illustrated by my screenshots

Expected behavior
Outlined elements should fit dark theme

Screenshots

System (please complete the following information):

• Browser Firefox 147.0.1
• App version 2.9.1
• Nextcloud version 32.0.5
• BigBlueButton version N/A
• Is your BigBlueButton instance working with Greenligh? N/A
• Did you enter your BBB API url and secret? yes
• Are you using a load balancer, like Scalelite? N/A

Nextcloud log:

Can be provided if necessary

Javascript log:

Can be provided if necessary

Additional context
Can be provided if necessary