Fix wrong display of motion/amendment

[Elblinator]

Current behaviour:
If a small enough width is reached the motion text + reason is below the meta-information + votes, but the meta-information and votes do not fill the whole width

Reproduction:

1. navigate to motions > motion-detail
2. width between 977px and 960px
3. the text and reason move to the end of the page, the meta-info stay squished at the left side:
   

Wanted behaviour:
The moment the text + reason move below the rest, the meta-information should fill the whole width

[Elblinator]

fixed by #2774