Actual value - CSS: Cascading Style Sheets 编辑

The actual value of a CSS property is the used value of that property after any necessary approximations have been applied. For example, a user agent that can only render borders with a whole-number pixel width may round the thickness of the border to the nearest integer.

Calculating a property's actual value

The user agent performs four steps to calculate a property's actual (final) value:

1. First, the specified value is determined based on the result of cascading, inheritance, or using the initial value.
2. Next, the computed value is calculated according to the specification (for example, a span with position: absolute will have its computed display changed to block).
3. Then, layout is calculated, resulting in the used value.
4. Finally, the used value is transformed according to the limitations of the local environment, resulting in the actual value.

Specifications

See also

• CSS Key Concepts: CSS syntax, at-rule, comments, specificity and inheritance, the box, layout modes and visual formatting models, and margin collapsing, or the initial, computed, resolved, specified, used, and actual values. Definitions of value syntax, shorthand properties and replaced elements.