弹出框

 html

        <div id="pop_out">
            <div id="pop">
                <h2>绑定会员卡</h2>
                <div class="pop_input">
                    <label>会员卡号</label>
                    <input type="number" placeholder="请输入会员卡号">
                </div>
                <button class="sure_btn">确定</button>
            </div>
        </div>

 css

#pop_out{
   width: 100%;
   background-color: rgba(0,0,0,.6);
   position: absolute;
   top: 0;
   left: 0;
   bottom: 0;
   z-index: 2;
}
#pop{
   width: 8.8rem;
   height: 8.6rem;
   margin: 0 auto;
   display: flex;
   flex-direction: column;
   align-items: center;
   background: linear-gradient(to bottom, #AB2622, #890301);
   position: fixed;
   top:50%;
   left: 50%;
   transform:translate(-50%,-50%);
   z-index: 2;
}