.image-left,
.image-right {
    position: absolute;
    position: fixed;
    top: 0;
    height: 200vh;
    width: 200px;
    background-size: cover;
    background-position: center;
    z-index: 20;
}

.image-left {
    left: 0;
    background-image: url("/assets/img/left.jpg");
}

.image-right {
    right: 0;
    background-image: url("/assets/img/right.jpg");
}

@media (max-width: 1700px) {
    .image-left,
    .image-right {
        width: 100px;
        display: block;
    }
}
@media (min-width: 1200px) {
    .image-left,
    .image-right {
        width: 80px;
        display: block;
    }
}
@media (min-width: 1350px) {
    .image-left,
    .image-right {
        width: 110px;
        display: block;
    }
}
@media (min-width: 1500px) {
    .image-left,
    .image-right {
        width: 200px;
        display: block;
    }
}
@media (max-width: 600px) {
    .image-left,
    .image-right {
        width: 40px;
        display: block;
    }
}
/* 1700px以下でも600px以下の条件を優先したい場合 */
@media (max-width: 600px) {
    @media (max-width: 1700px) {
        .image-left,
        .image-right {
            display: block;
        }
    }
}