ng-switch-when在切换div后保留前一个div空格

Question

这是我的代码：

      <div class="wh_box" ng-model="change_div" ng-switch on="change_div">
            <div ng-switch-when="unchanged">
            <ul class="shar_list">
                <li ng-repeat="dish_index in similar">
                    <h2><span>{{dish_index.Dish.name}}</span></h2>
                    <div>
                    <a><img no-image ng-src={{similarfull_image_url+dish_index.Dish.image}} alt=""></a>
                    </div>
                </li>
                <li ng-hide="similar.length" class="no_record">No record found</li>
            </ul>
                </div>
            <div ng-switch-when="changed">
                <div class="title">Comments</div>
                <div class = "line"></div>
                <ul class="comment_list">
                    <li ng-repeat="x in comments ">
                        <a><img no-image ng-src="{{profile_img_path.image_url_tiny+x.User.image}}" alt=""></a>
                        <div class="pro_deatil" >
                            <h2> {{x.User.name}} </h2>
                            <p>{{x.CommentDish.comment}}</p>
                        </div>
                        <div class="pro_like" >
                        </div>
                    </li>
                </ul>
                <div class="comment">
                    <textarea name="comment" rows="5" cols="10" ng-model="comment_data.comment" placeholder="Enter Comment" class="post_txt_area"  ng-blur="blurred()"  ></textarea>
                    <div> <a  ng-click="postComment()" class="event_btn">Comment</a> </div>
                </div>
            </div>
        </div>

我的问题： ng-switch工作正常但是当我切换到另一个div时，在新的切换div中仍然可以清楚地看到Previous div底部空间，请在这个问题上帮助我。