.mobile_top_pic{display:none;width:100%;}
.mobile_top_pic img{width:100%;}
@media screen and (max-width: 900px) {
#carousel-example-generic,.left_img {
    display: none;
    }
 .mobile_top_pic{display:block;}
}
/*限制幻灯片高度*/
.carousel{height: 200px;}
.carousel .item{height: 200px;}
/*图片可跟随窗口缩放*/
.carousel img{width: 100%;}
.footer {
    background-color: #222222;
    padding: 20px 0;
    color: rgba(255, 255, 255, 0.3);
    text-align: center;
}

.footer p {
    font-size: 14px;
    margin: 0;
}
.btn-group a:hover{text-decoration:none;}
.nav>li{text-align:center}
.navbar-nav>li>a {margin: 0 15px;}

.btn{margin: 0 0 5px 0;}