a topic-link {margin: 10px auto;display: block;width: 600px;} topic-box {width: 600px;height: 75px;b

a.topic-link {margin: 10px auto;display: block;width: 600px;}.topic-box {width: 600px;height: 75px;background: url("//tu.duoduocdn.com/uploads/d