header {
    background: url("../img/mockup.jpg");
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
    position: relative;
    overflow: hidden;
/*    -webkit-animation: sky_background 50s ease-out infinite;
    -moz-animation: sky_background 50s ease-out infinite;
    -o-animation: sky_background 50s ease-out infinite;
    -webkit-transform: translate3d(0, 0, 0);
    -moz-transform: translate3d(0, 0, 0);
    -o-transform: translate3d(0, 0, 0)*/
}
/*.clouds_one {
    background: url("../img/clouds/cloud_one.png");
    position: absolute;
    left: 0;
    top: 10%;
    height: 100%;
    width: 300%;
    -webkit-animation: cloud_one 50s linear infinite;
    -moz-animation: cloud_one 50s linear infinite;
    -o-animation: cloud_one 50s linear infinite;
    -webkit-transform: translate3d(0, 0, 0);
    -moz-transform: translate3d(0, 0, 0);
    -o-transform: translate3d(0, 0, 0)
}
.clouds_two {
    background: url("../img/clouds/cloud_two.png");
    position: absolute;
    left: 0;
    top: 30%;
    height: 100%;
    width: 300%;
    -webkit-animation: cloud_two 75s linear infinite;
    -moz-animation: cloud_two 75s linear infinite;
    -o-animation: cloud_two 75s linear infinite;
    -webkit-transform: translate3d(0, 0, 0);
    -moz-transform: translate3d(0, 0, 0);
    -o-transform: translate3d(0, 0, 0)
}
.clouds_three {
    background: url("../img/clouds/cloud_three.png");
    position: absolute;
    left: 0;
    top: 10%;
    height: 100%;
    width: 300%;
    -webkit-animation: cloud_three 100s linear infinite;
    -moz-animation: cloud_three 100s linear infinite;
    -o-animation: cloud_three 100s linear infinite;
    -webkit-transform: translate3d(0, 0, 0);
    -moz-transform: translate3d(0, 0, 0);
    -o-transform: translate3d(0, 0, 0)
}

@-webkit-keyframes cloud_one {
    0% {
        left: 0
    }
    100% {
        left: -200%
    }
}

@-webkit-keyframes cloud_two {
    0% {
        left: 0
    }
    100% {
        left: -200%
    }
}

@-webkit-keyframes cloud_three {
    0% {
        left: 0
    }
    100% {
        left: -200%
    }
}

@-moz-keyframes cloud_one {
    0% {
        left: 0
    }
    100% {
        left: -200%
    }
}

@-moz-keyframes cloud_two {
    0% {
        left: 0
    }
    100% {
        left: -200%
    }
}

@-moz-keyframes cloud_three {
    0% {
        left: 0
    }
    100% {
        left: -200%
    }
}*/