.button {
    /* margin and padding is not necessary, but I want something to be here (and use BEM) */
    margin: 0;
    padding: 0;
}

.button--big {
    width: 300px;
    height: 100px;
}

.button--big:active {
    color: #00f
}

.button--approve {
    width: 200px;
    height: 50px;
}

.button--approve:hover {
    color: brown;
}