Need help with max width of gallery in Flatiron

Site URL: http://be4media.com/#/motion/

Hello everyone! I know there is a solution out there and have searched and read some cool css codes but can not seem to apply it to this application. I would like the image gallery to either resize or scale with different display sizes or just increase the maximum with from 1200 to at least 1600. The issue is that the gallery does not center to most displays I have seen, it move justified left, even if it were just centered I would be happy. Any help would be so greatly appreciated. Thank you for your time. cheers ed

Add to Home > Design > Custom CSS

div#detail_57bd3c33f7e0ab7f80479e4e {
    max-width: 80% !important;
    margin: 0 auto !important;
}

THANK YOU SO MUCH TUANPHAN!!!!!