当之前有未使用的样式时，不应用Css样式

<div style="color: red;">This text will be red.</div>

<style>
    #myElement {
        color: blue;
    }
</style>

<div id="myElement">This text will be blue.</div>

<style>
    .myClass {
        font-size: 20px;
    }

    [type="text"] {
        background-color: yellow;
    }
</style>

<div class="myClass">This text will have a font size of 20 pixels.</div>

<input type="text" value="This text field will have a yellow background color." />

<style>
    p {
        color: green;
    }

    a:hover {
        text-decoration: underline;
    }
</style>

<p>This paragraph text will be green.</p>

<a href="#" title="Hover over me">This link will have underlined text when hovered over.</a>