MTP20_H5_PLUS/src/components/base/mask/index.less

.app-mask {
    top   : 0;
    left  : 0;
    width : 100%;
    height: 100%;

    &__block {
        position           : absolute;
        top                : 0;
        left               : 0;
        width              : 100%;
        height             : 100%;
        background-color   : rgba(0, 0, 0, .35);
        transition-property: opacity;

        &:not(.is-show) {
            opacity: 0;
        }
    }
}