.usecase #main .ttl_box .sub_ttl {
    font-family: "Microsoft YaHei", Arial, "Hiragino Sans GB", Sans-Serif;
    font-weight: bold;
}

.usecase #main {
    margin: 7.5rem 0.9375rem 9.375rem;
    letter-spacing: 0.1em;
}

.usecase #main .ttl_box .ttl img {
    height: 3.75rem;
}

.usecase #main .ttl_box .sub_ttl {
    color: #8517e5;
    font-size: 0.8125rem;
    letter-spacing: 0.1em;
    text-align: center;
    margin-top: 0.5rem;
}

.usecase #main .art .art_ttl {
    font-size: 1.4375rem;
    /*letter-spacing: 0.05em;*/
    font-family: "Microsoft YaHei", Arial, "Hiragino Sans GB", Sans-Serif;
    font-weight: bold;
    text-align: center;
    margin: 3.125rem 0 2.1875rem;
    line-height: 1;
}

.usecase #main .art .sec {
    margin-top: 1.875rem;
}

.usecase #main .art .sec .img_box span {
    display: block;
    background-color: #c8c6c6;
    background-image: url();
    background-repeat: no-repeat;
    background-position: center 0;
    background-size: cover;
    padding-top: 55%;
}

.usecase #main .art .sec .text_box .sec_ttl {
    margin: 1.25rem 0;
    font-size: 0.875rem;
    font-family: "Microsoft YaHei", Arial, "Hiragino Sans GB", Sans-Serif;
    font-weight: bold;
    line-height: 1;
}

.usecase #main .art .movie_wrap {
    display: block;
    padding: 3.125rem 0 0;
}

.usecase #main .art .movie_wrap .iframe {
    position: relative;
    width: 100%;
    padding-top: 55%;
}

.usecase #main .art .movie_wrap .iframe .iframe_container {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}

@media screen and (min-width: 768px) {
    .usecase #main {
        margin: 11.875rem auto 18.75rem;
        width: 80%;
    }

    .usecase #main .ttl_box .ttl img {
        height: 6.875rem;
    }

    .usecase #main .ttl_box .sub_ttl {
        font-size: 1.625rem;
        margin-top: 1.5625rem;
        line-height: 1;
    }

    .usecase #main .art .art_ttl {
        font-size: 2.8125rem;
        margin: 6.25rem 0 4.375rem;
    }

    .usecase #main .art .art_text {
        font-size: 1.875rem;
        text-align: center;
        line-height: 1.5;
    }

    .usecase #main .art .sec {
        margin-top: 5rem;
    }

    .usecase #main .art .sec .text_box .sec_ttl {
        margin: 3.125rem 0 2.5rem;
        font-size: 1.875rem;
    }

    .usecase #main .art .sec .text_box .sec_text {
        font-size: 1.7rem;
        line-height: 1.5;
    }

    .usecase #main .art .movie_wrap {
        padding: 6.5625rem 0 0;
    }
}