body.login {
background-image: url('../img/background/923-640x700.jpg');
background-position: center center;
background-repeat: no-repeat;
background-size: cover;
min-height: calc(100vh);
}
@media screen and (min-width: 640px){
body.login {
background-image: url('../img/background/923-960x700.jpg'); 
}
}	
@media screen and (min-width: 960px){
body.login {
background-image: url('../img/background/923-1200x900.jpg'); 
}
}	
@media screen and (min-width: 1200px){
body.login {
background-image: url('../img/background/923-1600x960.jpg'); 
}
}	
@media screen and (min-width: 1600px){
body.login {
background-image: url('../img/background/923-2000x1050.jpg'); 
}
}