user-groups: Add css for user-group-mention class.
user-groups: Add css for user-group-mention class.

dhcrzf/zulip,hackerkid/zulip,timabbott/zulip,tommyip/zulip,shubhamdhama/zulip,zulip/zulip,dhcrzf/zulip,tommyip/zulip,rht/zulip,punchagan/zulip,brainwane/zulip,punchagan/zulip,hackerkid/zulip,eeshangarg/zulip,tommyip/zulip,shubhamdhama/zulip,dhcrzf/zulip,punchagan/zulip,jackrzhang/zulip,punchagan/zulip,zulip/zulip,mahim97/zulip,hackerkid/zulip,andersk/zulip,rishig/zulip,shubhamdhama/zulip,eeshangarg/zulip,synicalsyntax/zulip,eeshangarg/zulip,shubhamdhama/zulip,mahim97/zulip,punchagan/zulip,kou/zulip,brainwane/zulip,rishig/zulip,rishig/zulip,brainwane/zulip,andersk/zulip,jackrzhang/zulip,zulip/zulip,tommyip/zulip,andersk/zulip,showell/zulip,rishig/zulip,showell/zulip,timabbott/zulip,jackrzhang/zulip,brainwane/zulip,shubhamdhama/zulip,showell/zulip,kou/zulip,jackrzhang/zulip,tommyip/zulip,brainwane/zulip,shubhamdhama/zulip,dhcrzf/zulip,eeshangarg/zulip,synicalsyntax/zulip,rht/zulip,rishig/zulip,jackrzhang/zulip,jackrzhang/zulip,eeshangarg/zulip,rht/zulip,timabbott/zulip,rht/zulip,kou/zulip,synicalsyntax/zulip,andersk/zulip,brainwane/zulip,kou/zulip,hackerkid/zulip,andersk/zulip,brainwane/zulip,zulip/zulip,timabbott/zulip,zulip/zulip,eeshangarg/zulip,zulip/zulip,tommyip/zulip,timabbott/zulip,zulip/zulip,hackerkid/zulip,showell/zulip,mahim97/zulip,dhcrzf/zulip,synicalsyntax/zulip,rht/zulip,rishig/zulip,rht/zulip,rht/zulip,eeshangarg/zulip,synicalsyntax/zulip,kou/zulip,rishig/zulip,hackerkid/zulip,tommyip/zulip,jackrzhang/zulip,mahim97/zulip,synicalsyntax/zulip,timabbott/zulip,kou/zulip,synicalsyntax/zulip,showell/zulip,mahim97/zulip,dhcrzf/zulip,punchagan/zulip,punchagan/zulip,andersk/zulip,timabbott/zulip,dhcrzf/zulip,mahim97/zulip,showell/zulip,hackerkid/zulip,kou/zulip,andersk/zulip,showell/zulip,shubhamdhama/zulip