Show booked out dates as disabled

booking-calendar.css

#bta-calendar a.fc-event {
  background-color: #69903B;
  border: 0 none;
  border-radius: 0;
  border-right-width: 0;
  border-top-right-radius: 0;
  border-bottom-right-radius: 0;
  border-left-width: 0;
  border-top-left-radius: 0;
  border-bottom-left-radius: 0;  
}
#bta-calendar a, #bta-calendar a.fc-event.booked-out:hover {color: #EEE}
#bta-calendar a:hover {color:#FFF}
#bta-calendar a.fc-event.booked-out {background-color:#AAA; cursor: default}
#bta-calendar table tr td {border-top: 0}