请问下面“立即选购”这边内外边距都没加，为什么会自动显示有空隙啊

请问下面立即选购这边内外边距都没加，外面的盒子也没加，为什么会自动显示有空隙啊求解答555

img


```css
* {
        margin: 0px;
        padding: 0px;
      }
      .box {
        box-sizing: border-box;
        width: 260px;
        height: 450px;
        margin: 50px auto;
        border: 1px solid black;
      }
      .pic {
        padding-top: 10px;
        text-align: center;
      }
      img {
        width: 50%;
      }
      .info {
        height: 40px;
        line-height: 20px;
        color: gray;
        font-size: 14px;
        margin: 0px 10px;
      }
      .jiage {
        height: 20px;
        line-height: 20px;
        margin-top: 30px;
        color: red;
        font-size: 25px;
        margin: 30px 10px 0px;
      }
      .jiage span {
        color: gray;
        font-size: 14px;
        text-decoration: line-through;
      }
      .xiaoshou {
        height: 15px;
        font-size: 12px;
        color: gray;
        line-height: 15px;
        margin-top: 15px;
        padding: 0px 10px;
      }
      .box3 {
        display: inline-block;
        width: 120px;
        height: 12px;
        line-height: 15px;
        border: 1px solid red;
        border-radius: 7px;
        padding: 1px;
      }
      .box3 .jdt {
        width: 87%;
        height: 100%;
        background-color: red;
        border-radius: 6px 0 0 6px;
        transition: width 1s;
      }
      .box3:hover .jdt {
        width: 100%;
        border-radius: 6px;
      }
      .footer {
        margin-top: 10px;
        width: 100%;
        height: 40px;
        background-color: red;
        line-height: 40px;
        text-align: center;
      }
      .footer a {
        text-decoration: none;
        color: white;
        font-size: 20px;
      }


 <body>
    <div class="box">
      <div class="pic"><img src="images/111.png" alt="" />div>
      <div class="info">
        Apple苹果iphone X (A1699) 32G 金色 移动联通电信4G手机
      div>
      <div class="jiage">
        ￥6088
        <span>￥6988span>
      div>
      <div class="xiaoshou">
        已售<e>87%e>
        <div class="box3"><div class="jdt">div>div>
        剩余<e>29e>件
        <div class="footer"><a href="#">立即抢购a>div>
      div>
    div>
  body>

```

img

因为你最外层设置了width: 260px，有用margin: 50px auto来水平居中了


 .footer {
                     margin-top: 10px;
                     width: 100%;
                     height: 40px;
                     background-color: red;
                     line-height: 40px;
                     text-align: center;
                     position: fixed;
                     bottom: 0;
                     left: 0;
                     z-index: 1000;
                   }

直接这么写吧，反正也是定到最下面