.cross table {
    border-spacing: 0;
    border-collapse: collapse;
}
.cross td {
    height: 25px;
    width: 25px;
    font-size: 16px;
    text-align: center;
    font-family: sans-serif;
}

.cross td.let{
    border: 1px solid black;
}
.cross .num .rnd{
    cursor: pointer;
}