sur "smoothness/jquery-ui.css", modifier:

.ui-widget-header {
	color: #222222;
	font-weight: bold;
}

.ui-widget-header .ui-state-default {
	border: 1px solid #ddd;
	background:linear-gradient(180deg,#fff,#f1f1f1);
	font-weight: normal;
	color: #555555;
}



sur "ui-darkness/jquery-ui.css", modifier:

.ui-widget-header {
	color: #ffffff;
	font-weight: bold;
}

.ui-widget-header .ui-state-default {
	border: 1px solid #444;
	background:linear-gradient(180deg,#444,#222);
	font-weight: bold;
	color: #eeeeee;
}