如何将CSS属性分别应用于多个元素

<style>
    .my-class {
        background-color: #f1f1f1;
    }
</style>

<div class="my-class">Element 1</div>
<div class="my-class">Element 2</div>
<div class="my-class">Element 3</div>

<style>
    p {
        color: red;
    }
</style>

<p>Paragraph 1</p>
<p>Paragraph 2</p>
<p>Paragraph 3</p>

<style>
    #my-element {
        font-size: 20px;
    }
</style>

<div id="my-element">This element has a font size of 20px.</div>

<style>
    a[target="_blank"] {
        color: blue;
    }
</style>

<a href="https://www.example.com" target="_blank">Link 1</a>
<a href="https://www.example.com" target="_self">Link 2</a>
<a href="https://www.example.com" target="_blank">Link 3</a>