[#75943444] refactoring & update modal CSS
[#75943444] refactoring modal related CSS
[#75943444] Merge remote-tracking branch 'origin/master' into 75943444-workbench
[#75943444] udpate Grunt build gengo.css & gengo-bootstrap-theme.css
Merge pull request #48 from gengo/75943444-workbench

[#75943444] Workbench related CSS changes