It looks like the quickest way to change that, and only that, could be to add the following to your /wp-content/theme/custom-community/style.css:
#header div.widgetarea {
background-color:transparent !important;
}
(you can also put background-color: #fff; for white)
This assumes that the theme is truly custom (e.g. no automatic updates, etc). If that theme’s instructions ask to put custom CSS someplace else, follow that instruction for location.
Hope that helps!
Ah, on the refresh, looks like you found it via .ccwidget too.
Good job.