#my_container {
    width: 100%;
    border: 1px solid #000000;
}

#my_container .my_container_row_1 {
    height: 50px;
    background: #FF0000;
}

#my_container .my_container_row_2 {
    height: 50px;
    background: #00FF00;
}

#my_container .my_container_row_3 {
    height: 50px;
    background: #0000FF;
}

#my_container .my_container_row_4 {
    display: block;
    width: 100%;
    margin: 5px; /* give this row a gap from the others */
    text-align: center; /* center it's contents */
}

/* NOTE: I am stling the image tag here, no css class specified, it will only affect the img tag in the CSS path #my_container .my_container_row_4 */
#my_container .my_container_row_4 img {
    border: 3px solid #000000;
}