可以有很多种位置
<style>
#third{height: 20px;width: 120px;background-color: violet;}
</style>
<link rel="stylesheet" href="./4.kb.css">
</head>
<body>
<div onclick="this.style.width='1000px';this.style.height='760px'" style="height: 120px;width: 200px;background-image: url('http://5b0988e595225.cdn.sohucs.com/images/20170920/e4832a83543f4fc7a5db9550ac297ccc.jpeg');border: 2px solid khaki;transition: 1.5s;"></div>
<div style="height: 50px;width:70px;border:2px solid yellowgreen;">行间样式</div>
<div id="third">内部样式</div>
<div id="fourth">外部样式</div>
<script>
var third=document.getElementById('third');
third.onclick=function(){alert('我排行第三!')}
</script>
<script src="./4.kb.js"></script>
</body>