.history{
    background: #d3d3d3;
    border: 30px solid #add8e6;
}
.parallex{
    min-height: 500px; 
    background-attachment: fixed;
    background-position: center;
    background-repeat: no-repeat;
    background-size: cover;
    margin: 5rem 0;
}
.iframe {
    position: relative;
    overflow: hidden;
    width: 100%;
    padding-top: 56.25%;
}
.responsive-iframe {
    position: absolute;
    top: 0;
    left: 0;
    bottom: 0;
    right: 0;
    width: 100%;
    height: 100%;
}


@media only screen and (max-width:768px){

}

@media only screen and (max-width:576px){

}

@media only screen and (max-width:400px){
.parallex{
min-height: 200px;
}
}

@media only screen and (max-width:280px){

}