HTML <h1>-<h6> class Attribute

The class attribute assigns one or more classnames to the <h1> to <h6> tags.

Classnames are defined in a stylesheet or in a local <style> element.

Classes, i.e. classnames, are used to style elements.



A class attribute styling an <h3> element.

The Innocence Project

  .heading-3 {display:inline-block; 
      border-bottom:3px solid #808cf8; padding-bottom:5px;}

  <h3 class="heading-3">The Innocence Project</h3>

Using class

Classes (i.e. classnames) are used for styling the h1-h6 elements.

Multiple classnames are separated by a space.

JavaScript uses classes to access elements by classname.

Tip:  class is a global attribute that can be applied to any HTML element.


<h1 class="classnames">



Value Description
classnames One or more space-separated class names.

More Examples

A class attribute styling an <h3> element.
Clicking the button toggles a classname that changes the bottom border color.

The Paris-Dakar rally

  .heading-3 {display:inline-block; 
      border-bottom:3px solid #808cf8; padding-bottom:5px;}  
  .border-red { border-bottom-color: orangered; }

  <h3 id="myheading" class="heading-3">The Paris-Dakar rally</h3>

<button onclick="toggle();">Toggle class</button>

  let toggle = () => {
    let element = document.getElementById("myheading");

Code explanation

Two CSS classes are defined in the <style> element.

The class attribute in <h3> assigns a single classname.

Repeatedly clicking the button toggles another class, changing the border color of the element.

Browser support

Here is when class support started for each browser:

1.0 Sep 2008
1.0 Sep 2002
1.0 Aug 1995
1.0 Jan 2006
1.0 Jan 2003

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 Back to <h1 to h6>

Author: Jack Poorte
Published: Jun 20 2021
Last Reviewed: Sep 30 2023

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