[mobile] gray writing implies inactivity

[mbohlender]

problem: the writing in the drop down menu on the right (' ... ') is gray for all inactive features and the active features are marked in black. 'x close' is also an active feature but shown in gray writing which implies inactivity

https://git.kolab.org/file/data/xg2kqhto5qhqqzb7jqqo/PHID-FILE-qhr45bpzkuzsbg64qw46/grafik.png

solution: change colour of 'x close' to black

[alecpl]

This is waiting for a designer. I though we may even change the header background color on phones. So, the text color would become white.

[alecpl]

Duplicate of #113.