.BlackButton {
    font-size: 16px;
    line-height: 24px;
    vertical-align: top;
    background-color: black;
    color: white;
    transition-property: background-color, color;
    transition-duration: 0.3s;
    transition-timing-function: ease-in-out;
    font-size: 18px;
    border: 1px solid black;
    padding: 5px;
}
.BlackButton:hover {
    background-color: white;
    color: black;
}