Hi all, We are actively moving away from GWT and towards react [https://reactjs.org/] in webadmin, so the CSS needs to be in a place where both can access it. Moving forward, please avoid using any and all of GWT's CSS features when working in webadmin. This new(ish) place is sass: [ https://github.com/oVirt/ovirt-engine/tree/master/frontend/brands/ovirt-bran... ] Sass is easy to use, and hopefully the structure makes sense. So -- don't use <ui:style> nor addStyleNames="{style.whatever}"> instead, <g:FlowPanel ui:field="xyz" addStyleNames="prefix_className"> more examples here [1] (prefix == the sass file name) For programmatic manipulation, simply hardcode style names in Java code and don't use GWT's Style: widget.addClassName("notif_someClassName") etc. Best wishes, Greg [1] https://github.com/oVirt/ovirt-engine/blob/f14587eb9deab300c31247b6941a2d67d... Sass package: https://github.com/oVirt/ovirt-engine/tree/master/frontend/brands/ovirt-bran... -- GREG SHEREMETA SENIOR SOFTWARE ENGINEER - TEAM LEAD - RHV UX Red Hat NA <https://www.redhat.com/> gshereme@redhat.com IRC: gshereme <https://red.ht/sig>