I had a similar issue. After redefining .ui-priority-secondary as mentioned in your post, I added this
.ui-state-highlight, .ui-widget-content .ui-state-highlight {border: 1px solid #fad42e; background: #fbec88 50% 50% repeat-x; color: #363636; }
.ui-state-highlight:hover, .ui-widget-content .ui-state-highlight:hover {border: 1px solid #fad42e; background: #fbec88 50% 50% repeat-x; color: #363636; }
This seems to work.