.datepicker > div > table > thead th {
  background: none;
  padding: 0%;
}

.calendar-form {
  /*margin-top: 12px;*/
  font-size: 12px;
  color: #73879C;
  font-family: Roboto-Medium;
}

.calendar-title {
  margin-right: 10px;
  margin-top: 17px;
}

.date-input {
  width: 100px;
  text-align: center;
  height: 23px;
  border: 2px #73879C solid;
}

.go-button {
  height: 25px;
  color: #FFFFFF;
  background: #73879C;
  padding-top: 3px;
}

.datepicker > div > table > thead th {
  background: none;
  padding: 0%;
}

.calendar-form {
  /*margin-top: 12px;*/
  font-size: 12px;
  color: #73879C;
  font-family: Roboto-Medium;
}

.calendar-title {
  margin-right: 10px;
  margin-top: 17px;
}

.date-input {
  width: 100px;
  text-align: center;
  height: 23px;
  border: 2px #73879C solid;
}

.go-button {
  height: 22px;
  color: #FFFFFF;
  background: #73879C;
  padding-top: 2px;
  padding-bottom: 19px;
  border: 1px #73879C solid;
}

Modify css to 'GO' button
Modify css to 'GO' button
