header {
    background-image: url("Ti_cut.jpg"); 
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;

    padding: 100px 20px;
    text-align: center;
    color: white;
}
#about {
    background-image: url("Ti_lattice_inverted.jpg");
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
    
    color: #ffffff;
    padding: 80px 40px;
    min-height: 600px;
}
/* body {
    margin: 0;
    background-image: url("Ti_lattice.jpg");
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
    background-attachment: fixed; 
} */