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CSS inheritance propagates property values from a parent element to a child when the property's defaulting rules call for it. For an inherited property, the child normally receives the parent's CSS computed value if it has no applicable declaration supplying another value. A property that is not inherited instead normally uses its CSS initial value. The root has no parent from which to inherit.^[ref]

Suppose a parent has font-size: 20px and a child specifies font-size: 150%. The child computes to 30 CSS pixels. If a grandchild merely inherits font size, it receives 30 pixels; it does not multiply the original 150 percent again. This is why inheriting a computed value differs from copying the parent's source text.

The keyword inherit can request inheritance even for a property that does not normally inherit. Thus a width declaration with that keyword is a deliberate instruction, whereas omitting width does not automatically copy the parent's width. The exact result still depends on that property's value-processing rules.^[ref]

Importance does not spread down the tree as selector priority. If a parent obtains red from an important color declaration, a child with its own ordinary blue color declaration can be blue. The parent contributed a possible inherited value; it did not create an important declaration on the child. Distinguishing CSS inheritance from the CSS cascade explains both shared styling and local overrides.

A CSS initial value is the value defined as a property's starting point by its specification. It participates in defaulting when an element has no other specified value under the applicable rules. It is distinct from a browser's default stylesheet declaration and from the value obtained by CSS inheritance.^[ref]

For example, the initial value of display is inline, while a browser normally supplies styling that makes a paragraph block-level. Setting p { display: initial; } requests the property's initial value, rather than restoring the browser's usual paragraph appearance. The paragraph's HTML element semantics remain separate from that display choice.

The keyword initial explicitly requests this starting value. inherit requests the parent's computed value instead, and unset chooses inheritance for inherited properties and the initial value for non-inherited properties. Thus these keywords can produce different results even when they appear in the same selector and win the same CSS cascade comparison.^[ref]

Initial values also need their normal processing. A width initially set to auto still requires the appropriate sizing algorithm; initial does not mean that every property begins as zero or already has a final pixel size. The sequence from defaulting through computation to the CSS used value explains how a specification-defined starting value becomes a concrete rendering.