header {  
    background-image: url(../assets/robot.jpeg);
}
.intro .img {
    background-image: url(../assets/study_robot.png);
}
.products .img.img1{
    background-image: url(../assets/products/47.jpg);
}
.products .img.img2 {
    background-image: url(../assets/products/35.jpg);
}
.products .img.img3 {
    background-image: url(../assets/products/57.png);
}
.products .img.img4 {
    background-image: url(../assets/products/67.jpg);
}