繼承

摘要

每個 CSS property definition 都寫道是否這個屬性預設有繼承: ("Inherited: Yes") 或是 預設沒有繼承: ("Inherited: no"). 這個設定將會在沒有位屬性標註值時發生.

繼承屬性

When no value for an inherited property has been specified on an element, the element gets the computed value of that property on its parent element. Only the root element of the document gets the initial value given in the property's summary.

A typical example of an inherited property is the color property. Given the style rules:

p { color: green }

HTML:

<p>This paragraph has <em>emphasized text</em> in it.</p>

the words "emphasized text" will appear green, since the em element has inherited the value of the color property from the p element. It does not get the initial value of the property (which is the color that is used for the root element when the page specifies no color).

非繼承屬性

When no value for an non-inherited property (sometimes called a reset property in Mozilla code) has been specified on an element, the element gets the initial value of that property (as specified in the property's summary).

A typical example of a non-inherited property is the border property. Given the style rules:

 p { border: medium solid }

HTML:

  <p>This paragraph has <em>emphasized text</em> in it.</p>

the words "emphasized text" will not have a border (since the initial value of border-style is none).

註

inherit 關鍵字允許作者準確地去標註. 這個在繼承和非繼承屬性都是有效的.

參見

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