css 标签选择器、id选择器、类选择器实例

<code class="language-html">


<style>
p
{
background-color:yellow;
}
</style>



<h1>Welcome to My Homepage</h1>

<div>
<p id="firstname">My name is Donald.</p>
<p id="hometown">I live in Duckburg.</p>
</div>

<p>My best friend is Mickey.</p>


</code>

<code class="language-html">


<style>
#firstname
{
background-color:yellow;
}
</style>



<h1>Welcome to My Homepage</h1>

<div class="intro">
<p id="firstname">My name is Donald.</p>
<p id="hometown">I live in Duckburg.</p>
</div>

<p>My best friend is Mickey.</p>


</code>

<code class="language-html">


<style>
.intro
{
background-color:yellow;
}
</style>



<h1>Welcome to My Homepage</h1>

<div class="intro">
<p>My name is Donald.</p>
<p>I live in Duckburg.</p>
</div>

<p>My best friend is Mickey.</p>


</code>