Show promoted speaker avatar / placeholder bigger

[jancborchardt]

In our company calls the promoted speaker avatar / placeholder is shown as big as the other ones. It would be cool to show it a bit bigger. Twice the size seems good.

Additionally it would be cool for the avatar be also used in a blurred version to cover the whole background. Kind of like it’s on video platforms for portrait videos which are shown in landscape. Can be done entirely in CSS, I just need to have a second avatar container to do that with. :)

(Rescued from approach at #334, which didn’t seem to work.)

[jancborchardt]

Closing in favor of #309 which has basically the same points. :)