Signed-off-by: Norman Ziegner <norman.ziegner@ufz.de>

- Use image overlays for the cards
- Use mix-blend-mode to make contrast high enough
- Show post image if one is defined

- Restructure the introduced components a little
- Fix links on the mission page
- Remove unused file consulting-iframe

- Also make use of the {%- syntax to reduce whitespace in the generated
HTML for the team member includes
- Fix alignment of title in the section part

https://www.helmholtz.de/fileadmin/user_upload/04_mediathek/Logos_2017/2017_H_Logo_RGB_untereinander_EN.png