Add support for prefers-color-scheme: dark in banner

Header now also supports dark theme. To enable that add a monochrome
version of the eclipse logo. The logo is dark on light background in
the light theme and light on dark background in the dark theme.

Change-Id: I047348532f74a95dae7014c1b1e69e1ffe3af534
Signed-off-by: Matthias Becker <ma.becker@sap.com>
3 files changed