.masthead {
    height: 2vh;
    min-height: 350px;
    background-image: url('./img-9913-rz.jpg');
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
}

.datepicker {
    font-size: 0.875em;
}

/* solution 2: the original datepicker use 20px so replace with the following:*/

.datepicker td,
.datepicker th {
    width: 1.5em;
    height: 1.5em;
}