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CSS CSS Basics (2014) Understanding Values and Units Styling the Intro Paragraph

For CSS multiple selectors, when do you need a comma and when you only need a space?

selector1, selector2 { }

vs

selector1 selector2 { }

index.html
<!DOCTYPE html>
<html>
  <head>
    <title>Lake Tahoe</title>
    <link rel="stylesheet" href="page.css">
    <link rel="stylesheet" href="style.css">
  </head>
  <body> 
    <header id="top" class="main-header">
      <span class="title">Journey Through the Sierra Nevada Mountains</span>
      <h1>Lake Tahoe, California</h1>
    </header>
    <div class="primary-content t-border">
      <p class="intro">
        Lake Tahoe is one of the most <span>breathtaking attractions</span> located in California. It's home to a number of ski resorts, summer outdoor recreation, and tourist attractions. Snow and skiing are a significant part of the area's reputation.
      </p>
      <a href="#more">Find out more</a>
    </div>
    <footer class="main-footer">
      <p>All rights reserved to the state of <a href="#">California</a>.</p>
      <a href="#top">Back to top &raquo;</a>
    </footer>
  </body>
</html>
style.css
/* Complete the challenge by writing CSS below */

.intro {
  font-size: 1.25em;
  line-height: 1.6;
}

.intro, span {
  font-weight: bold;
  font-style: italic;
}

1 Answer

A space is used to select elements nested within other elements. For example, the following CSS rule selects any paragraph elements that are located inside of a div:

div p {

}

While the comma is used to select multiple elements. The following rule makes each of the heading elements selected the color blue:

h1, h2, h3 {
    color: blue;
}

Let me know if this helps!

So,

div p {

}

and

p div {

}

would match different things?

Yes. The first rule selects any and all paragraph elements that are nested within a div. Like the p element here:

<div>
    <p>hi</p>
</div>

The second rule selects any div elements that are nested within a paragraph element. Like the div element here:

<p>
    <div>yo</div>
</p>