请问一个简单的样式有关问题

body{
    font-size:12px;
    font-family:"黑体", Arial;
}
a:link {
    color: #999;
}
a:visited {
    color: #999;
}
a:hover {
    color: #999;
}
a:active {
    color: #999;
}
.body_area{
    width:1240px;
}
.main_area{
    float:left; width:960px;
}
.friend_area{
    float:left; width:100%; overflow:auto; height:530px;
}
.friend_card{
    float:left; width:300px; height:50px; margin:5px;border:solid #B8D4E8 1px;
}
.friend_grade{
    float:left; width:50px; height:100%; background-color: #B8D4E8; color:#FFFFFF; font-size:24px; text-align:center;line-height:50px;
}
.friend_detail{
    float:left; width:200px; height:100%;
}
.friend_param{
    float:left; width:50px; height:15px; background-color:#F0F5F8; text-align:center; line-height:15px;
}
.friend_param_bottom_slave{
    float:left; width:50px; height:15px; background-color: #EC7000; text-align:center; line-height:15px;
}
.friend_param_bottom_master{
    float:left; width:50px; height:15px; background-color: #ADDC0E; text-align:center; line-height:15px;
}
.friend_param_content{
    float:left; width:50px; height:20px; text-align:center; line-height:20px;
}
.friend_headPic{
    float:left; width:50px;height:100%;
}
.friend_headPic_img{
    width:50px; height:50px;
}
.friend_data{
    float:left; width:140px;
}
.person_area{
    float:left; display: none;
}
.person_param{
    float:left; width:110px;height:70px; margin:5px;
}
.person_head{
    height:20px;text-align:center; line-height:20px; background-color:#B8D4E8; font-size:14px; color:#FFFFFF;
}
.person_body{
    height:50px;text-align:center; line-height:50px; background-color:#F0F5F8; font-size:20px; font-weight:bold; color:#B8D4E8;
}
.ctrl_area{
    float:left; width:100%; margin:5px; display: none;
}
.task_area{
    float:left; width:260px; margin-left:5px; display:none;
}
.task_target{
    width:100%;margin-top:5px;
}
.task_target_title{
    float:left; background-color:#B8D4E8;font-size:18px; height:30px; color:#FFFFFF;width:60px; font-size:18px; text-align:center; line-height:30px; margin-bottom:5px;
}
.task_target_body{
    float:left; background-color:#F0F5F8;font-size:18px; height:30px; color:#B8D4E8;width:200px; font-size:16px; text-align:center; line-height:30px;margin-bottom:5px;
}
.task_head{
    margin-top:10px;border-bottom: #B8D4E8 solid 2px;color: #09C;height:20px;line-height:20px; text-align:center;
}
.task_head_no{
    float:left;width:30px;
}
.task_head_user{
    float:left; width:40px;
}
.task_head_name{
    float:left;width:40px; 
}
.task_head_time{
    float:left;width:150px; 
}
.task_param{
    float:left; width:100%;height:35px; line-height:35px;text-align:center; border-bottom:#B8D4E8 solid 1px;
}
.task_param_no{
    float:left; background-color:#F0F5F8; color:#B8D4E8; width:30px; font-size:18px; font-weight:bold;
}
.task_param_user{
    float:left; width:40px;
}
.task_param_name{
    float:left; width:40px;
}
.task_param_time{
    float:left; width:150px;
}
.login_dialog{
    border: #B8D4E8 solid 1px;
    text-align:center;
    width:300px;
    height:320px;
    top: 50%;
    left: 50%;
    margin-left:-150px;
    margin-top:-180px;
    background-color: #F0F5F8;
    position: absolute;
    position:fixed;
}

.login_text{
    float:left;
    height:25px;
    width:170px;
    border:1px #B8D4E8 solid;
    display:inline-block;
    background-color:#FFF
}

.login_text_id{
    width:135px;
    height:20px;
    border:none;
    vertical-align: top;
    line-height:20px;
    font-size:14px;
}

.login_text_pwd{
    width:160px;
    height:20px;
    line-height:20px;
    font-size:14px;
    border:none;
}

.login_user{
    padding:5px;
    cursor:pointer;
}

.login_select_user{
    border:none;
    width:25px;
    height:25px;
    cursor:pointer;
}

.login_user_list{
    width:170px; 
    display:none;
    font-size:14px;
    text-align:left;
    position:absolute;
    background-color:#FFF; 
    border:1px #B8D4E8 solid; 
    border-top:0px;
    margin:-4px 0px 0px -261px; 
}

.login_btn{
    border:none;
    width:150px;
    height:30px;
    color:#FFF;
    background-color:#369;
}

.login_error{
    color: #F00;
}

.login_msg{
    text-align:right;
    width:270px;
}

.ctrl_area{
    float:left;width:100%;height:40px; line-height:40px;
}

.ctrl_btn{
    border:none;width:100px;height:30px;color:#FFF;margin-left:-5px;background-color:#369;
}

.dialog_area{
    border: #B8D4E8 solid 1px;
    background-color: #F0F5F8;
    top: 50%;
    left: 50%;
    margin-left:-155px;
    margin-top:-50px;
    width:300px;
    height:100px;
    position: absolute;
    position:fixed;
    padding:5px;
    display:none;
}
.dialog_user{
    float:left;
    width:80px;
    height:65px;
    border-right: #B8D4E8 solid 1px;
}
.dialog_user_pic{
    text-align:center;
}
.dialog_user_name{
    height:10px;
    width:100%;
    text-align:center;
}
.dialog_detail{
    float:left;
    width:200px;
    height:60px;
    margin-left:10px;
}
.dialog_detail_title{
    float:left;
    width:40px;
    height:20px;
    text-align:center;
    line-height:20px;
}
.dialog_detail_param{
    float:left;
    width:150px;
    height:20px;
    line-height:20px;
    border-bottom: #EAEAEA solid 1px;
}
.prog_bar{
    background-color:#B8D4E8;
    text-align:center;
    color:#FFF;
}
.log_area{
    float:left;
    width:100%;
    width:1225px;
    height:230px;
    display:none;
}

.log_msg{
    text-align:center;
}
.log_head_tr{
    color:#FFF;
    height:15px;
    line-height:15px;
    font-size:14px;
    text-align:center;
    background-color:#B8D4E8;
}
.setting_dialog_area{
    border: #B8D4E8 solid 1px;
    background-color: #F0F5F8;
    top:50%;
    left:50%;
    margin-left:-200px;
    margin-top:-230px;
    width:400px;
    height:460px;
    position: absolute;
    position:fixed;
    display:none;
}
.setting_dialog_title{
    background-color: #B8D4E8;
    height:20px;
    color:#369;
    padding-left:5px;
    line-height:20px;
    font-size:14px;
    font-weight:bold;
}