.img1 {
    width: 150px;
    height: 130px;
    background-image: url(img/perpertuum.png);
    background-size: cover;
    float: right;
    margin: 1em;
}

.img2 {
    width: 250px;
    height: 250px;
    background-image: url(img/machine.jpg);
    background-size: cover;
    float: right;
    margin: 1em;
}

.img3 {
    width: 350px;
    height: 197px;
    background-image: url(img/speedup.jpg);
    background-size: cover;
    float: right;
    margin: 1em;
}

.img4 {
    width: 530px;
    height: 308px;
    background-image: url(img/sheme.png);
    margin: 1em;
    display: inline-block;
}