CSS Properties: How to set the opacity level for a division element

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HTML Code:

<!DOCTYPE html><!-- Declares the document type and version of HTML -->
<html><!-- Begins the HTML document -->
<head><!-- Contains metadata and links to external resources -->
<title>How to set the opacity level for a division element</title><!-- Sets the title of the document -->
<style type="text/css"> /* Starts CSS styling */
div {  /* Selects all div elements */
  background-color: #33C3FF; /* Sets the background color for all div elements */
	} /* Ends the styling for div */

.heavy { /* Selects elements with the class "heavy" */
  opacity: 0.9; /* Sets the opacity level for elements with the class "heavy" */
} /* Ends the styling for .heavy */
</style><!-- Ends CSS styling -->
</head><!-- Ends the head section -->
<body><!-- Begins the body of the document -->
<p>w3resource Tutorial</p><!-- Paragraph element with text content -->
<div class="heavy">The text and the background-color, both are affected by the opacity level but this is very easy to see.</div><!-- Div element with the class "heavy" -->
</body><!-- Ends the body section -->
</html><!-- Ends the HTML document -->


  • This HTML document demonstrates how to set the opacity level for a division element using CSS.
  • CSS comments are added to explain each section of the code.
  • All div elements have a background color of #33C3FF.
  • The class "heavy" is defined to set an opacity level of 0.9 for elements with this class.
  • The text and background color of elements with the "heavy" class are affected by the opacity level set.

Live Demo:

See the Pen opacity-answer by w3resource (@w3resource) on CodePen.

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