Experiment card proportions on tablet

[manuelzomer]

Describe the bug
In portrait orientation on a tablet, the experiment cards within the landing page are more than twice as wide than their height, this can be a tricky aspect ratio for users to add a fitting cover photo.

To Reproduce
Steps to reproduce the behavior:

1. Create an experiment
2. Look at the experiments overview page (landing page)

Expected behavior
The height of the experiment card should grow according to the width to keep (about) the same aspect ratio as on a smaller phone screen. This is also the behaviour on iOS.

Screenshots
Android:

iOS: