#calendar {
  width: 100%;
  border-collapse: collapse;
}

#calendar tbody td {
  border: 1px solid black;
  text-align: right;
  vertical-align: top;
  width: 14%;
}

/* Styles for the day boxes, in order of importance */
#calendar td.weekday {
   background-color: LightGreen;
}

#calendar td.weekend {
  background-color: yellow;
}

#calendar td.holiday {
  background-color: orange;
}

#calendar td.invalid {
   background-color: LightGray
}

#calendar td.invalid.holiday {
   background-color: LightGray;
   text-decoration: underline;  /* This style to show that there is a holiday on an invalid day. */
   cursor: pointer;
}