.left-column-settings-page {
    float: left;
    width: 65%;
    width: calc(100% - 350px);
}

.right-column-settings-page {
    max-width: 306px;
    float: right;
}

.right-column-settings-page img {
    max-width: 100%;
}

.metabox-holder .postbox h3 {
    padding-left: 10px;
}

@media screen and (max-width: 640px) {

    .left-column-settings-page {
        width: 100%;
    }

    .right-column-settings-page {
        float: left;
        clear: both;
        margin-top: 10px;
    }
}