#mainImg {
    display: -webkit-box;
    display: -ms-flexbox;
    display: flex;
    -webkit-box-pack: center;
    -ms-flex-pack: center;
    justify-content: center;
    -webkit-box-align: center;
    -ms-flex-align: center;
    align-items: center;
    position: relative;
    background-image: url(../img/contents/flow-bil-bg-l.png), url(../img/contents/flow-bil-bg-r.png);
    background-position: left bottom, right bottom;
    background-repeat: no-repeat;
}

#mainImg:before {
    content: "";
    position: absolute;
    height: 80%;
    background-repeat: no-repeat;
    background-size: contain;
    bottom: 0;
    right: 0;
}

.qa #mainImg:before {
    background-image: url(../img/contents/qa-bil-bg.png);
}

/* 767px 未満 */
@media screen and (max-width: 767px) {

    #mainImg {
        height: 100px;
        background-size: auto 20%;
    }

    #mainImg:before {
        width: 100px;
    }

    .qa #mainImg:before {
        background-position: right bottom;
    }
}

/* End max 767px */

/* 幅 768px 以上 */
@media screen and (min-width: 48em) {

    /* ビルボ */
    #mainImg {
        height: 200px;
        background-size: 45%;
    }

    #mainImg:before {
        width: 324px;
    }

    .line #mainImg:before {
        background-position: left 3em bottom;
    }

}

/* End min 768px */

/* 幅 880px 以上 */
@media screen and (min-width: 55em) {}

/* End min 880px */

/* 幅 1072px 以上 */
@media screen and (min-width: 67em) {

    #mainImg:before {
        right: calc((100vw - 1000px) / 2);
    }

}

/* End min 1072px */

/* 幅 1264px 以上 */
@media screen and (min-width: 79em) {
    #mainImg {
        background-size: auto;
    }

}

/* End min 1264px */

/* 幅 1600px 以上 */
@media screen and (min-width: 1600px) {}