Background color widgets | Community Development | Sandbox ConnAct

 First, specify your CSS class in the Advanced tab of your widget, in this case I called mine mywidgetclass:

Second, use Chrome Developer tools or any css friendly tool to look at the CSS classes available to modify, in the example below i'm going to change the widget header background color to Yellow:

Third, add your CSS code to Control Panel > System > CSS Overrides

Fourth, enjoy your results:

NOTTE: to use whits smoke background i have added follwoign css code to css override:

.mywidgetbackground .container-fluid {background-color: whitesmoke; }

in the widget class just type: mywidgetbackrgound