anchor.diff:          .form-control {
               margin-bottom: 20px;
           }
  -        .col-md-6{
  +
  +        .col-md-6 {
               margin-top: 1em;
           }
       </style>
  
positive.code:         <form class="form-signin" method="post" action="${basePath }login">
              <h2 class="form-signin-heading">请登录：<p style="color: red" id="errorinfo_id">${returninfo }</p></h2>
              <div class="form-group" id="Id_div">
                  <input type="number" name="username" class="form-control" id="inputID" placeholder="学号" required
                         autofocus>
                  <span class="glyphicon glyphicon-remove form-control-feedback" aria-hidden="true"></span>
              </div>
  
negative.code:                 </label>
              </div>
              <div class="row">
                  <div class="col-md-6">
                      <button class="btn btn-lg btn-primary btn-block" type="button" id="submit_id">登录</button>
                  </div>
                  <div class="col-md-6">
                      <button onclick="window.open('${basePath }qqLogin','_self');" type="button"
                              class="btn btn-lg btn-primary btn-block">使用QQ账户登录
                      </button>
                  </div>
              </div>
          </form>
          <p style="height: 8px"></p>
  