实现代码如下：
<div class="wrap">
<div class="img"></div>
<div class="notice">1</div>
</div>
<div class="wrap">
<div class="img"></div>
<div class="notice">12</div>
</div>
<div class="wrap">
<div class="img"></div>
<div class="notice">13</div>
</div>
<style>
.wrap {
width:50px
margin-bottom:10px
position:relative
}
.img {
width:50px
height:50px
border:1px solid #000
}
.notice {
width:20px
height:20px
line-height:20px
font-size:10px
color:#fff
text-align:center
background-color:#f00
border-radius:50%
position:absolute
right:-10px
top:-10px
}
</style>
扩展资料：注意事项
主要用到position定位，CSS position属性用于指定一个元素在文档中的定位方式。top、right、bottom、left 属性则决定了该元素的最终位置。
static是position的默认值。
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>CSS-position-static</title>
<link rel="stylesheet" href="https://cdn.bootcss.com/normalize/8.0.0/normalize.css">
<style>
.container{
background-color: #868686
width: 100%
height: 300px
}
.content{
background-color: yellow
width: 100px
height: 100px
position: static
left: 10px/* 这个left没有起作用 */
}
</style>
</head>
<body>
<div class="container">
<div class="content">
</div>
</div>
</body>
</html>
上述样式一般通过取消默认的list标记，然后以图片的形式实现；但是，也可以直接设置li的样式实现，思路是在li标签下嵌套span标签，然后将li的样式设置为红色，字号较大，而span为正常的样式。下面给出后者的实例演示：
创建Html元素
<div class="box"><span>通过设置li及其子元素span的不同样式将li默认的黑色标记改为红色，且显示较大：</span><br>
<div class="content">
<ul class="test">
<li><span>Glen</span></li>
<li><span>Tane</span></li>
<li><span>John</span></li>
<li><span>Ralph</span></li>
</ul>
</div>
<div class="content">
<ul>
<li>Glen</li>
<li>Tane</li>
<li>John</li>
<li>Ralph</li>
</ul>
</div>
</div>
设置css样式
div.box{width:300pxpadding:20pxmargin:20pxborder:4px dashed #ccc}div.box>span{color:#999font-style:italic}
div.content{width:250pxmargin:10px 0padding:20pxborder:2px solid #ff6666}
li{margin:5px 0}
ul.test li{color:redfont-size:30px}
ul.test li span{display:inline-blockcolor:blackfont-size:16px}
观察对比效果
<!DOCTYPE HTML><html>
<meta charset="UTF-8">
<title>test</title>
<head>
<style type="text/css">
body {
margin: 0 auto
text-align: center
font-family: "微软雅黑"
}
.normal {
background: url(http://pic.58pic.com/58pic/14/82/90/81B58PIC52m_1024.jpg) no-repeat
background-size: 6px
background-position: 95% 45%
}
.error {
background: url(http://static7.depositphotos.com/1222693/712/i/170/depositphotos_7122979-Red-button.jpg) no-repeat
background-size: 9px
background-position: 95% 45%
border-color: red
}
.warning {
visibility: hidden
font-size: 12px
background: red
color: white
padding: 1px
margin-left: 5px
}
</style>
<script type="text/javascript">
window.onload = function() {
var myinput = document.getElementById('myinput')
var myspan = document.getElementById('myspan')
//失去焦点事件
myinput.onblur = function() {
if(!myinput.value || isNaN(myinput.value)) {
this.className = 'error'
this.title = '请输入此字段'
this.focus()
myspan.style.visibility = 'visible'
} else {
this.className = 'normal'
this.title = ''
myspan.style.visibility = 'hidden'
}
}
}
</script>
</head>
<body>
<div>
<input class="normal" type="text" id="myinput" /><span id="myspan" class="warning">请输入数字</span>
</div>
</body>
</html>
