css at rule descriptor

`fallback` CSS at-rule descriptor

The fallback descriptor of the @counter-style at-rule can be used to specify a counter style to fall back to if the counter style being defined cannot create a marker representation for a particular counter value.

Syntax

/* Keyword values */
fallback: lower-alpha;
fallback: custom-gangnam-style;

Value

The descriptor takes a single <counter-style-name> as its value:

<counter-style-name>
- : Provides the name of the counter style to be used as the fallback, which is either the case-sensitive <custom-ident> of a custom CSS counter style (without quotes) or a case-insensitive list-style-type property value such as decimal, disc, and so on.

If omitted, the counter fallback defaults to decimal.

Description

The counter style provided as the value of the fallback descriptor is used when a range descriptor is specified for a counter style; the fallback style is used to represent all the values that fall outside the range. The fallback style is also used when the fixed system is used and there are not enough symbols to cover all the list items; the fallback style is used to represent all the values beyond the scope of the fixed system. In both these cases, and any other time the defined counter cannot create a specific counter value, the fallback style is used.

If the specified fallback style is also unable to construct a representation, then the fallback value of that fallback counter is used. If that fallback style’s fallback is also unable to construct a representation, then that fallback’s fallback is used. This falling back continues until a fallback is found that can construct the counter-representation. If no fallback fallback value is able to construct a representation―if a fallback style doesn’t have a fallback value set, or if a fallback value is not specified or invalid―the fallback defaults to decimal.

Formal definition

Formal syntax

Examples

Specifying a fallback counter style

HTML

<ul class="list">
  <li>One</li>
  <li>Two</li>
  <li>Three</li>
  <li>Four</li>
  <li>Five</li>
</ul>

CSS

@counter-style fallback-example {
  system: fixed;
  symbols: "\24B6" "\24B7" "\24B8";
  fallback: upper-alpha;
}

.list {
  list-style: fallback-example;
}

Result

Interactive exampleOpen the canonical MDN source to run this embedded demo.

Specifications

SpecificationsStandards references are available on the canonical MDN page.

Browser compatibility

Browser compatibilityCompatibility data is available on the canonical MDN page.