CSS all

<!DOCTYPE html>
<title>Example</title>	
<style>
body {
  background: gold;
  color: green;
  font-family: serif;
  font-size: 2em;
}
p {
  background: yellowgreen;
}
.parent {
  color: white;
  font-family: sans-serif;
  font-size: .7em;
  font-style: italic;
  padding: 5px;
  border: 1px solid black;
}
.c2 {
  all: inherit;
}
.c3 {
  all: unset;
}
.c4 {
  all: initial;
}
</style>

Body
  
<div class="parent">
  Parent
  <p>c1</p>
  <p>c1</p>
  <p class="c2">c2</p>
  <p class="c2">c2</p>
  <p class="c3">c3</p>
  <p class="c3">c3</p>
  <p class="c4">c4</p>
  <p class="c4">c4</p>
</div>

The CSS all property resets all CSS properties (except direction and unicode-bidi).

This property can be handy for styling items such as widgets, that need to be styled independently of the outer page. In such cases, styles from the outer page could ruin the display of the widget if they are allowed to cascade down.

Syntax

Possible Values

initial

Represents the value specified as the property's initial value.

This value effectively resets all properties and block all inheritance as if no styles had been applied to the content. It therefore blocks any style sheet from the page from cascading down to the element. It also blocks browser/user agent styles, as well as any user specified styles.

Because of this, you may need to re-establish certain styles, such as display: block on <p>, <div> and <blockquote> elements for example, as these are established at the user agent level.

inherit

Represents the computed value of the property on the element's parent (i.e. inherits property values from the parent).

unset

Acts as either inherit or initial, depending on whether the property is inherited or not (i.e. sets all properties to their parent value if they are inheritable or to their initial value if not inheritable).

Basic Property Information

Initial Value: See individual properties
Applies To: See individual properties
Inherited?: See individual properties
Media: See individual properties
Computed Value: See individual properties
Animatable: See individual properties

Example Code

Basic CSS

Working Example within an HTML Document

Try it

CSS Specifications

The all property is defined in the CSS Cascading and Inheritance Level 3 (W3C Candidate Recommendation, 19 May 2016)

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.