HTML <sub> style Attribute

A style attribute on a <sub> tag assigns a unique style to the element.

Its value is CSS that defines the appearance of the sub element.



A style attribute on a <sub> tag.

The formula for water is H2O.

  The formula for water is 
  H<sub style="color:red;font-weight:bold;">2</sub>O.

Using style

The style attribute specifies the style, i.e. look and feel, of the <sub> element.

A style contains any number of CSS property/value pairs, separated by semicolons (;).

The style attribute overrides any other style that was defined in a <style> tag or an external CSS file.

This inline styling affects the current <sub> element only.


<sub style="CSS-styles">



Value Description
CSS-styles One or more CSS property/value pairs separated by semicolons (;).

More Examples

A style attribute on a <sub> tag.
Clicking the button toggles the text color.

The formula for water is H2O.

  The formula for water is 
  H<sub id="mysub" style="color:red; font-weight:bold;">2</sub>O.

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

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

    if ( === "red") { = "teal";
    } else { = "red";

Code explanation

The style attribute assigns a text color to the <sub> element.

Clicking the button calls JavaScript which toggles the text color to another color.

Browser support

Here is when style 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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Author: Jack Poorte
Published: Jun 20 2021
Last Reviewed: Sep 30 2023

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