* {
    margin: 0;
    padding: 0;
}
main {
    height: 1100px;
    background: url("img/background2.jpg") no-repeat center;
    background-size: cover;
    -webkit-background-size: cover;
    -o-background-size: cover;
}

/* 黑色半透明层 */
.black_background {
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
}

/* 导航栏 */
header {
    width: 100%;
    height: 60px;
}
.logo {
    height: 50px;
    margin: 5px 15px;
}
ul {
    float: right;
    height: 60px;
    margin: 0 30px;
}
li {
    float: left;
    width: 90px;
    height: 60px;
    line-height: 60px;
    margin: 0 5px;
    list-style-type: none;
    text-align: center;
    cursor: pointer;
    color: #ecb745;
    font-size: 15px;
}
header a {
    display: block;
    text-decoration: none;
    font-weight: bold;
}
header a:link, header a:visited {
    color: #ecb745;
    text-decoration: none;
}
header a:hover, header a:active {
    background-color: rgba(255, 255, 255, 0.2);
    border-bottom: 2px solid #ecb745;
}

/* 联系我们 */
.mytitle {
    height: 100px;
    margin: 150px 0;
    text-align: center;
}
.mytitle p {
    font-size: 30px;
    font-weight: bold;
    color: white;
    position: relative;
    z-index: 1;
}
.title_div {
    width: 150px;
    height: 20px;
    margin: 0 auto;
    background-color: #ecb745;
    position: relative;
    top: -15px;
    z-index: 0;
}
.contact_div {
    width: 800px;
    height: 350px;
    margin: 100px auto;
    padding: 50px 100px;
    background-color: rgba(255, 255, 255, 0.9);
    text-align: center;
}
.contact_div p {
    font-size: 15px;
    font-weight: bold;
    color: #444444;
    margin-top: 15px;
}

footer {
    width: 100%;
    height: 300px;
    background-color: #333333;
}
.footer_left_div {
    width: 600px;
    height: 200px;
    margin: 50px;
    float: left;
}

.footer_logo {
    height: 60px;
}
.footer_link_div {
    width: 300px;
    height: 50px;
    margin: 30px 0;
}
.linkedin_link {
    display: block;
    width: 50px;
    height: 50px;
    margin-right: 30px;
    background: url("img/领英.png") center no-repeat;
    background-size: 50px 50px;
    float: left;
}
.zhihu_link {
    display: block;
    width: 50px;
    height: 50px;
    background: url("img/知乎.png") center no-repeat;
    background-size: 50px 50px;
    float: left;
}
.footer_left_div p{
    clear: left;
    color: white;
    font-size: 15px;
}
.footer_right_div {
    width: 200px;
    height: 200px;
    margin: 50px;
    float: right;
    text-align: center;
}
.QRcode {
    width: 180px;
    height: 180px;
    margin-bottom: 10px;
}
.footer_right_div p{
    color: white;
    font-size: 15px;
}