padding box与定位数值为0的绝对定位

HTML

<a href="javascript:" class="list"> <img src="book-cover.svg" class="cover">
<div class="cell">
    <h4 class="title">标题1</h4>
    <p class="desc">点击下面的按钮改变列表padding大小会发现右上角红色几个标签依然固定在那个位置，具有更强的是适应性。</p>
</div>
<span class="tag">标签1</span> </a> <a href="javascript:" class="list"> <img src="book-cover.svg" class="cover">
<div class="cell">
    <h4 class="title">标题2</h4>
    <p class="desc">这是很长的一段描述内容，为什么会这么长纯粹是为了多点文字撑场面。</p>
</div>
<span class="tag">标签2</span> </a> <a href="javascript:" class="list"> <img src="book-cover.svg" class="cover">
<div class="cell">
    <h4 class="title">标题3</h4>
    <p class="desc">这是很长的一段描述内容，为什么会这么长纯粹是为了多点文字撑场面+1。</p>
</div>
<span class="tag">标签3</span> </a>

					    

CSS

body { width: auto; }
.list {
    display: block;
    max-width: 600px;
    margin: auto;
    padding: 1rem;
    color: #333;
    box-shadow: 0 1px #f0f1f2;
    overflow: hidden;
    position: relative;
    -webkit-tap-highlight-color: rgba(0,0,0,.1);
}
.cover {
    width: 60px;
    height: 80px;
    background-color: #eee;
    float: left;
    margin-right: .75rem;
}
.cell { overflow: hidden; }
.title {
    margin: 0 0 .25rem;
    font-size: 1rem;
}
.desc {
    margin: 0;
    color: gray;
}
.tag {
    font-size: 12px;
    font-weight: 300;
    line-height: 16px;
    position: absolute;
    right: 0;
    top: 0;
    height: 16px;
    padding: 0 .5rem 0 3px;
    background-color: #e00;
}
.tag::first-line { color: #fff; }
.tag::before {
    top: 0;
    content: "";
    position: absolute;
    left: -12px;
    border-width: 8px 6px;
    border-style: solid;
    border-color: #e00 #e00 transparent transparent;
}
.btn-test {
    display: block;
    margin: 2em auto;
    width: 280px;
    height: 2rem;
    font-size: 100%;
}
a img { border: none; }
a { text-decoration:none;}

					    

JS

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