.fade-bg {
    height: 40vh;
    width: 100%;
    overflow: hidden;
    /* 背景画像暗くする */
    background: linear-gradient(to bottom, rgba(0, 0, 0, 0.1), rgba(0, 0, 0, 0.1));
    background-size: cover;
}
.fade-bg__inner {
    position: relative;
    z-index: -100;
}
.fade-bg__inner div {
    opacity: 0;
    transition: 4s;
}
.fade-bg__inner div.show-img {
    opacity: 1;
}
.fade-bg__inner .bg-img {
    position: absolute;
    top: 20vh;
    left: 50%;
    transform: translate(-50%, -50%);
    max-height: initial;
    max-width: initial;
    min-height: 40vh;
    min-width: 100%;
}