cubicweb-brainomics #3501794 Facets CSS [validation pending]

The facets CSS should be modified to have a cleaner display.

prioritynormal
typebug
done in0.8.0
load0.100
load left0.000
closed by#f039b32e9a9e [facets] Fix facets box display, closes #3501794
patch[facets] Fix facets box display [applied]