theme-customizations.css

/*
* Node-RED Dashboard
*/
.nr-db-sb-group-list li {
  border-bottom-color: var(--red-ui-secondary-background) !important;
}

.nr-db-sb-list-handle {
  color: var(--red-ui-primary-text-color) !important;
}

.nr-db-sb-list-header,
.nr-db-sb-tab-list-item {
  color: var(--red-ui-primary-text-color) !important;
}

.nr-db-sb-list-header:hover,
.nr-db-sb-group-list-header:hover,
.nr-db-sb-widget-list-header:hover {
  background-color: var(--red-ui-primary-background) !important;
  color: var(--red-ui-primary-text-color) !important;
}

.nr-db-sb-tab-list-header {
  background-color: var(--red-ui-secondary-background) !important;
}