<!DOCTYPE html><html><head><meta charset="utf-8"><title>Bootstrap 辅助类</title><link rel="stylesheet" href="http://cdn.static.runoob.com/libs/bootstrap/3.3.7/css/bootstrap.min.css"> <style>div{width: 600px;height: 300px;}</style></head><body><div class="container"><div class="bg-primary">.bg-primary</div><div class="bg-success">.bg-success</div><div class="bg-info">.bg-info</div><div class="bg-w...