.main {
     height: 100vh;
     width: 100vw;
     position: relative;
     background-color: #2f2f2f;
}
 #login_center, .alert {
     z-index: 9999;
}
 .d1 {
     position: absolute;
     background-image: url(https://images.unsplash.com/photo-1464822759023-fed622ff2c3b?ixlib=rb-4.0.3&ixid=MnwxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8&auto=format&fit=crop&w=2070&q=80);
     background-size: 2700px 1500px;
     height: 30vh;
     width: 15vw;
     background-position: 0 50%;
     box-shadow: 0px 0px 25px rgba(0, 0, 0, 0.8);
     top: 50%;
     transform: translateY(-50%);
     z-index: 2;
     animation: dd1 10s 1, dd12 10s 1;
     animation-delay: 4s, 14s;
}
 .d2 {
     position: absolute;
     background-image: url(https://images.unsplash.com/photo-1464822759023-fed622ff2c3b?ixlib=rb-4.0.3&ixid=MnwxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8&auto=format&fit=crop&w=2070&q=80);
     background-size: 2700px 1500px;
     height: 50vh;
     width: 25vw;
     background-position: -10vw 50%;
     left: 10vw;
     top: 50%;
     transform: translateY(-50%);
     z-index: 1;
     animation: dd2 10s 2;
     animation-delay: 4s;
}
 .d3 {
     position: absolute;
     background-image: url(https://images.unsplash.com/photo-1464822759023-fed622ff2c3b?ixlib=rb-4.0.3&ixid=MnwxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8&auto=format&fit=crop&w=2070&q=80);
     background-size: 2700px 1500px;
     overflow: hidden;
     height: 100vh;
     width: 40vw;
     left: 25vw;
     box-shadow: 0px 0px 25px rgba(0, 0, 0, 0.8);
     background-position: -35vw 50%;
     top: 50%;
     transform: translateY(-50%);
     z-index: 3;
     animation: dd3 10s 2;
     animation-delay: 4s;
}
 .d4 {
     position: absolute;
     overflow: hidden;
     background-image: url(https://images.unsplash.com/photo-1464822759023-fed622ff2c3b?ixlib=rb-4.0.3&ixid=MnwxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8&auto=format&fit=crop&w=2070&q=80);
     background-size: 2700px 1500px;
     height: 80vh;
     width: 25vw;
     left: 60vw;
     background-position: -70vw 50%;
     top: 50%;
     transform: translateY(-50%);
     z-index: 1;
     animation: dd4 10s 2;
     animation-delay: 4s;
}
 @keyframes dd1 {
     0% {
    }
     50% {
         width: 95vw;
    }
}
 @keyframes dd12 {
     0% {
    }
     50% {
         background-position: Calc(0vw - 40px) 50%;
    }
}
 @keyframes dd2 {
     0% {
    }
     50% {
         background-position: Calc(-10vw - 40px) 50%;
    }
}
 @keyframes dd3 {
     0% {
    }
     50% {
         background-position: Calc(-35vw - 40px) 50%;
    }
}
 @keyframes dd4 {
     0% {
    }
     50% {
         background-position: Calc(-70vw - 40px) 50%;
    }
}