.dropdown {
    float: left;
    overflow: hidden;
}

    .dropdown .dropbtn {
        font-size: 16px;
        border: none;
        outline: none;
        color: #1b2336;
        padding: 14px 16px;
        background-color: inherit;
        font: inherit;
        margin: 0;
    }



.dropdown-content {
    display: none;
    position: absolute;
    background-color: #fff;
    width: 100%;
    left: 0;
    box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
    z-index: 1;
}

    .dropdown-content .header {
        background: red;
        padding: 16px;
        color: white;
    }

.dropdown:hover .dropdown-content {
    display: block;
}

.column {
    float: left;
    width: 33%;
    padding: 10px;
    background-color: #fff;
    height: 520px;
}

    .column a {
        float: none;
        color: black;
        padding: 16px;
        text-decoration: none;
        display: block;
        text-align: left;
    }

        .column a:hover {
            background-color:;
        }

/* Clear floats after the columns */
.row:after {
    content: "";
    display: table;
    clear: both;
}

.w500 {
    width: 500px;
}

#w500 {
    width: 600px;
}

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

    .w500 {
        width: 100%;
    }

    #w500 {
        width: 100%;
    }
}