CSS text-underline-position

<!DOCTYPE html>
<title>Example</title>
<style>
h1 {
  font: 100 3em sans-serif;
  text-decoration: underline;
  text-underline-position: under;
}
</style>

<h1>Example</h1>

The CSS text-underline-position property sets the position of an underline specified on the element.

The text-underline-position property is used in conjunction with the text-decoration-line property (or the text-decoration shorthand property) to determine where the line should appear.

If left or right is specified, under is implied.

Syntax

Possible Values

auto: The browser/user agent may use any algorithm to determine the underline's position; however it must be placed at or under the alphabetic baseline.
under: The underline is positioned under the element's text content. In this case the underline usually does not cross the descenders. This is sometimes referred to as "accounting" underline. It is lower than a normal "alphabetic" underline. This value can be combined with left or right if a particular side is preferred in vertical writing modes.
left: Used when presenting text in a vertical writing mode (eg, the text reads vertically from top to bottom or vice versa).
In vertical writing modes, the underline is aligned as for under, except it is always aligned to the left edge of the text. If this causes the underline to be drawn on the "over" side of the text, then an overline also switches sides and is drawn on the "under" side.
right: Used when presenting text in a vertical writing mode (eg, the text reads vertically from top to bottom or vice versa).
In vertical writing modes, the underline is aligned as for under, except it is always aligned to the right edge of the text. If this causes the underline to be drawn on the "over" side of the text, then an overline also switches sides and is drawn on the "under" side.

In addition, all CSS properties also accept the following CSS-wide keyword values as the sole component of their property value:

initial: Represents the value specified as the property's initial value.
inherit: Represents the computed value of the property on the element's parent.
unset: This value acts as either inherit or initial, depending on whether the property is inherited or not. In other words, it sets all properties to their parent value if they are inheritable or to their initial value if not inheritable.

Basic Property Information

Initial Value: auto
Applies To: All elements
Inherited?: Yes
Media: Visual
Animatable: No

Example Code

Basic CSS

Here's an example of a basic declaration. A declaration consists of the property and its value.

Working Example within an HTML Document

Try it

CSS Specifications

The text-underline-position property is defined in CSS Text Decoration Module Level 3 (W3C Candidate Recommendation 1 August 2013).

Browser Support

The following table provided by Caniuse.com shows the level of browser support for this feature.

Vendor Prefixes

For maximum browser compatibility many web developers add browser-specific properties by using extensions such as -webkit- for Safari, Google Chrome, and Opera (newer versions), -ms- for Internet Explorer, -moz- for Firefox, -o- for older versions of Opera etc. As with any CSS property, if a browser doesn't support a proprietary extension, it will simply ignore it.

This practice is not recommended by the W3C, however in many cases, the only way you can test a property is to include the CSS extension that is compatible with your browser.

The major browser manufacturers generally strive to adhere to the W3C specifications, and when they support a non-prefixed property, they typically remove the prefixed version. Also, W3C advises vendors to remove their prefixes for properties that reach Candidate Recommendation status.

Many developers use Autoprefixer, which is a postprocessor for CSS. Autoprefixer automatically adds vendor prefixes to your CSS so that you don't need to. It also removes old, unnecessary prefixes from your CSS.

You can also use Autoprefixer with preprocessors such as Less and Sass.

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