.ui-datepicker{ font-size: 12px; width: 220px; }
.ui-datepicker select.ui-datepicker-month{ width:35%; font-size: 12px; }
.ui-datepicker select.ui-datepicker-year{ width:35%; font-size: 12px; }

/*
.ui-datepicker-week-end {color:red;}
.ui-datepicker-week-end .ui-state-default {color:red;}
*/
.ui-datepicker-calendar > tbody td.ui-datepicker-week-end:first-child a { color:#f00; } 
.ui-datepicker-calendar > tbody td.ui-datepicker-week-end:last-child a { color:#00f; }