<h1>This is a heading.</h1>
<p>This is paragraph.</p>
<p>This is paragraph.</p>
<style type="text/css">
h1 + p {margin-top:50px;}
</style>相邻兄弟选择器用 + 号连接
父级元素指向子集元素用><style>
.father{
color: yellow;
}
.father:hover>.son{
color: red;
}
.father:hover+.fatherB{
color: blue;
}
.father:hover+.fatherB>.sonB{
color: green;
}
</style>
<body>
<div class="father">father
<div class="son">son</div>
</div>
<div class="fatherB">父亲
<div class="sonB">儿子</div>
</div>
</body>
