.main_div {
    width: 940px;
    margin: 10px auto;
    border: 1px solid #ececec;
}

.top_div {
    width: 900px;
    height: 40px;
    font-weight : bold;
    line-height: 40px;
    margin: 10px auto;
}
.nav_div {
    width: 800px;
    height: 40px;
    margin: 10px auto;
    line-height: 40px;
}

.nav_div ul li {
    text-align: center;
    float: left;
    width: 160px;
    height: 25px;
    line-height: 20px;
    list-style-type: none;
    border: 1px solid #0180B5;
    font-size: 14px;
    font-weight: bold;
}

.nav_div a {
    display: block;
}

.sell_div {
    display: block;
    width: 860px;
    margin: 20px auto;
}

.buy_title_div, .sell_title_div, .rent_title_div, .wanted_title_div {
    height: 30px;
    line-height: 30px;
    font-size: 14px;
    font-weight: bold;
    text-align: center;
}

.buy_content_div, .sell_content_div, .rent_content_div, .wanted_content_div {
    width: 860px;
    background-color: #F6F7FC;
}

.buy_content_div form, .sell_content_div form, .rent_content_div form, .wanted_content_div form {
    width: 800px;
    line-height: 50px;
    margin: 10px auto;
}

.buy_main_content_div, .sell_main_content_div, .rent_main_content_div, .want_main_content_div {
    text-align: center;
    width: 700px;
    margin: 0 auto;
}

.button_div {
    width: 300px;
    margin: 10px auto;
}

.button_div input {
    height: 30px;
    line-height: 20px;
}