Removed 0 length units in dark css.
Removed 0 length units in dark css.

Units for zero length values should be removed
https://www.hack23.com/sonar/coding_rules?activation=true&open=css%3Azero-units&qprofile=AV24ged_ZY6yaUNwuVuK
duzun/jstree,iCasa/jstree,Project-TF/jstree,iCasa/jstree,vakata/jstree,vakata/jstree,iCasa/jstree,Project-TF/jstree,duzun/jstree