.g-headbg {
    display: block;
}
.common_head {
    display: none;
}
@media screen and (min-width: 300px) and (max-width: 750px) {
    .g-headbg {
        display: none;
    }
    .common_head {
        display: flex;
        align-items: center;
        justify-content: center;
        background: #fff url(../images/c_topback.png) repeat-x center bottom;
        padding: 15px 0;
        position: relative;
        z-index: 90;
    }
    .common_head a{
        display: block;
        width: 90vw;
        margin: 0 auto;
    }
    .common_head a img {
        width: 100%;
    }
}