@media screen and (min-width: 1102px) {

}
@media screen and (max-width: 1101px) {
    #web_app{width:990px; margin: 0 calc(100% - 990px) 0 0;}
}

@media screen and (max-width: 993px) {
    #web_app{width:760px; margin: 0 calc(100% - 760px) 0 0;}
}

@media screen and (max-width: 769px) {
    #web_app{width:480px; margin: 0 calc(100% - 480px) 0 0;}
}

@media screen and (max-width: 481px) {

}