#bg-slider {
    position: relative;
    width: 100%;
    height: 150vw;
}

@media (min-width: 769px) {
    #bg-slider {
        height: 100vh;
    }
}

.slide {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-size: cover;
    background-position: center;
    transition: opacity 1.5s ease-in-out;
}

.slide {
    background-image: url('../img/mv/01.webp');
}

@media (max-width: 768px) {
    .slide {
        background-image: url('../img/mv/01-sp.webp');
    }
}

@media screen and (min-width: 769px) {
    main #bg-slider {
        position: absolute;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        z-index: 1;
        background: #000;
    }

    main #bg-slider div {
        position: absolute;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        background-size: cover;
        background-position: center;
        opacity: 0;
        transition: opacity 2s ease-in-out;
    }

    main #bg-slider .slide {
        position: absolute;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        background-size: cover;
        background-position: center;
    }

    main #bg-slider div.is-active {
        opacity: .8;
    }
}

@media screen and (max-width: 768px) {
    main #bg-slider {
        position: absolute;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        z-index: 1;
        background: #000;
        aspect-ratio: 9 / 16;
        background-color: #f0f0f0;
        position: relative;
        overflow: hidden;
    }

    main #bg-slider div {
        position: absolute;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        background-size: cover;
        background-position: center;
        opacity: 0;
        transition: opacity 2s ease-in-out;
    }

    main #bg-slider div.is-active {
        opacity: .8;
    }
}