.square {
    width: 10rem;
    height: 10rem;
    background-color: #eee;
    margin: 1rem;
    float: left; /* place next to each other */
}
.first {
    border: 2px red solid
}

.second {
    border-left: 16px blue double;
    border-right: 16px blue double;
    border-top: 4px blue dashed;
    border-bottom: 4px blue dashed;
}

.third {
    border-left: 24px green dotted;
}

.fourth {
    border: 16px orange groove;
}

.fifth {
    border-right: 8px grey solid;
    border-bottom: 16px purple solid;
}