Use full opacity for online state icons

The green now fully shines while I made the full black ring border a
dark grey.

To increase contrast, on suggestion by @grote.
3 jobs for online-state-transparency in 3 minutes and 25 seconds (queued for 1 minute and 47 seconds)
Status Job ID Name Coverage
  Test
passed #6032
pycodestyle

00:01:19

passed #6033
pylint

00:02:05

manual #6034
allowed to fail manual
pytest