body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    background: none;
}

.sphere {
    position: relative;
    width: 400px;
    height: 400px;
    border-radius: 50%;
    transform-style: preserve-3d;
    animation: spin 50s linear 1;
    animation-fill-mode: forwards;
    will-change: transform;
}

@media screen and (max-width: 445px) {

    /* ここに横幅が990px以下の時に発動するスタイルを記述 */
    /* topでは画面の1/2でiframeのため半分の閾値で調整の必要あり */
    .sphere {
        width: 200px;
        height: 200px;
    }

    .single.sphere {
        width: calc(100vw - 20px);
        height: calc(100vw - 20px);
    }
}

/* 経線 */
.sphere .meridian {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border: 1px dotted rgba(255, 255, 255, 0.4);
    border-radius: 50%;
}

/* 緯線 */
.sphere .parallel {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border: 1px dotted rgba(255, 255, 255, 0.4);
    border-radius: 50%;
}