a.topic-link {margin: 10px auto;display: block;width: 600px;}.topic-box {width: 600px;height: 75px;background: url("//tu.duoduocdn.com /上传/day_160627/201606271101388748.png") 重复-x;margin: 0 auto;position: 相对；}.topic-thumb {position:...