main {
    border: 5px lightgrey solid;
    background-image: url(bg_check.png)
}
main .left {
    margin: 2.5% 0;
    display: block;
    width: 100%;
    min-height: 25%;
    text-align: left;
}
.left img {
    padding: 0 2.5%;
    height: auto;
    max-width:50%;
    float: left;
}
main .right {
    margin: 2.5% 0;
    display: block;
    width: 100%;
    min-height: 25%;
    text-align: right;
}
.right img {
    padding: 0 2.5%;
    height: auto;
    max-width:50%;
    float: right;
}