/* sp */

@media screen and (max-width: 520px) {
    .book-midashi {
        background: #fff9dd;
        border-left: 8px solid #bbe08c;
        padding: 8px 0 8px 10px;
        font-size: 16px;
    }

    .book-intro-width {
        width: 200px;
    }

    .book-width {
        width: 250px;
    }



   



}


@media screen and (min-width: 521px) {
    .book-midashi {
        background: #fff9dd;
        border-left: 12px solid #bbe08c;
        padding: 10px 0 10px 13px;
        font-size: 20px;
    }

    .book-intro-width {
        width: 300px;
    }

    .book-width {
        width: 350px;
    }


}

.youtube-container {
    position: relative;
    width: 100%;
    padding-bottom: 56.25%;
    /* 16:9の比率 (高さ/幅=9/16) */
    height: 0;
    overflow: hidden;
}

.youtube-container iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}