* {
    box-sizing: border-box;
}

article {
    float: left;
    padding: 20%;
    width: 70%;
    height: 300px;
}

section::after {
    content: "";
    display: table;
    clear: both;
}


.column {
    float: left;
    width: 33.33%;
    padding: 15px;
    color: chartreuse;
    border: 5px unset black;
}

.row::after {
    content: "";
    display: table;
    clear: both;
    border: 5px unset black;

}

@media screen and (max-width: 600px) {
    .column {
        width: 100%;
    }
    
}