*{
    padding:0;
    margin:0;
}
table{
    width:1000px;
    margin:100px;
    border-collapse:collapse;/*边框合并模式*/
    text-align:center;
}
td,th{
    border:1px solid #333;
}
thead tr{
    height:40px;
    background-color: #cccccc;
}