/*超大屏幕*/
@media screen and (min-width: 1900px) {
    .page_bg {
        height: 600px;
        background-size: 100% 600px;
    }
}

/*大屏幕*/
@media screen and (min-width: 769px) {
    .page_bg {
        height: 450px;
        background-size: 100% 450px;
    }

    .content {
        width: 90%;
        margin: 0 auto;
        letter-spacing: 1px;
    }

    .about_us_content {
        margin-top: 60px;
        color: #717171;
        line-height: 30px;
        font-size: 16px;
    }

    .div_art_head
    {
        margin: 60px 0;
        text-align: center;
        color: #00269a;
    }

    .div_title {
        font-size: 20px;
        font-weight: bold;
    }

    .sub_title {
        margin-top: 10px;
        font-size: 16px;
    }

    .div_hr {
        width: 50%;
    }

    .div_hr hr {
        background-color: #00269a;
        border: none;
        height: 1px;
        opacity: .8;
    }

    .div_files {
        font-size: 16px;
        line-height: 34px;
    }
}

.about_us_content img{display:block;margin:0 auto;}