table, th, td {
    border: solid 2px black;
    border-collapse: collapse;
}

table {
    margin: auto;
}


td {
    color: white;
    background-color: #424242 ;
    min-width: 50px;
    text-align: center;
}

.empty {
    background-color: darkgray;
}

.table-header {
    color: white;
    background-color: lightblue;
}

.table-header .blank {
    background-color: lightgray;
}

h2 {
    text-align: center;
    text-decoration: underline;
}