#mask {
    position: relative;
    margin-bottom: 20px;
    overflow-x: hidden
}

#mask::after {
    background: transparent;
    background: -moz-linear-gradient(left, rgb(229, 229, 229) 0%, rgba(229, 229, 229, 0.8) 100%);
    background: -webkit-linear-gradient(left, rgb(229, 229, 229) 0%, rgba(229, 229, 229, 0.8) 100%);
    background: -o-linear-gradient(left, rgb(229, 229, 229) 0%, rgba(229, 229, 229, 0.8) 100%);
    background: -ms-linear-gradient(left, rgb(229, 229, 229) 0%, rgba(229, 229, 229, 0.8) 100%);
    background: linear-gradient(to left, rgb(229, 229, 229) 0%, rgba(229, 229, 229, 0.8) 100%);
    content: "";
    display: block;
    height: 100%;
    width: calc((100% - 1210px) / 2);
    position: absolute;
    top: 0;
    right: 0;
}

#mask .container {
    background: transparent;
}

#mask .container::after {
    background: transparent;
    background: -moz-linear-gradient(right, rgb(229, 229, 229) 0%, rgba(229, 229, 229, 0.8) 100%);
    background: -webkit-linear-gradient(right, rgb(229, 229, 229) 0%, rgba(229, 229, 229, 0.8) 100%);
    background: -o-linear-gradient(right, rgb(229, 229, 229) 0%, rgba(229, 229, 229, 0.8) 100%);
    background: -ms-linear-gradient(right, rgb(229, 229, 229) 0%, rgba(229, 229, 229, 0.8) 100%);
    background: linear-gradient(to right, rgb(229, 229, 229) 0%, rgba(229, 229, 229, 0.8) 100%);
    content: "";
    display: block;
    height: 100%;
    width: calc((100% - 1210px) / 2);
    position: absolute;
    top: 0;
    left: 0;
}

@media (max-width: 559px) {
    #mask::after, #mask .container::after {
        width: 2.5%;
    }
}

@media (min-width: 560px) and (max-width: 767px) {
    #mask::after, #mask .container::after {
        width: /*7.5%*/ calc((100% - 540px) / 2);
    }
}

@media (min-width: 768px) and (max-width: 991px) {
    #mask::after, #mask .container::after {
        width: calc((100% - 728px) / 2);
    }
}

@media (min-width: 992px) and (max-width: 1299px) {
    #mask::after, #mask .container::after {
        width: calc((100% - 896px) / 2);
    }
}