body {
  margin: 0;
}

#links {
    float: left;
    width: 20%;
    padding: 15px;
}

#iframe {
    float: left;
    width: 75%;
    height: 900px;
}

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

@media screen and (max-width: 1075px) {
    #links {
        width: 100%;
    }

    #sectionA {
        float: left;
        width: 40%;
        padding: 15px;
    }

    #sectionB {
        float: left;
        width: 40%;
        padding: 15px;
    }

    #iframe {
        width: 100%;
        height: 900px;
    }
}