The "!important" was missing in darkgreen.css. As a result the inline color wasn't overruled. (probably in more color sets)
body[class*=preset-dark] section.dexp-section {
background-color: #292929 !important;
}
Hello Edwin,
We have fixed this bug on latest version but it was only a setting bug. You can fix it by accessing to http://yoursiteurl.com/admin/appearance/settings/jollyness
At layout Shop Layout 1, 2,3 tab click on gear of Featured Product section, delete #292929 at background color textfield and input class greybg to Custom class textfield.
and save all changes.
Sorry about this issue.
Thanks,