August 2015
Beginner to intermediate
718 pages
20h 46m
English
Content preview from CSS: The Missing Manual, 4th EditionBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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Chapter 4. Saving Time with Style Inheritance
Children inherit traits from their parents—eye color, height, male-pattern baldness, and so on. Sometimes we inherit traits from more distant ancestors, like grandparents or great-grandparents. As you saw in the previous chapter, the metaphor of family relations is part of the structure of HTML as well. And just like humans, HTML tags can inherit CSS properties from their ancestors.
What Is Inheritance?
Inheritance is the process by which some CSS properties applied to one tag are passed on to nested tags. For example, a <p> tag is always nested inside of the <body> tag, so properties applied to the <body> tag get inherited by the <p> tag. Say you created a type selector style (Creating an External Style Sheet) for the <body> tag that sets the color property to a dark red. Tags that are descendants of the <body> tag—that is, the ones inside the <body> tag—will inherit that color property. That means that any text in those tags —<h1>, <h2>, <p>, or whatever—will appear in that same dark red color.
Inheritance works through multiple generations as well. If a tag like the <em> or <strong> tag appears inside of a <p> tag, then the <em> and the <strong> tags also inherit properties from any style applied to the <body> tag.
Note
As discussed in Chapter 3, any tag inside of another tag is a descendant of that tag. So a <p> tag inside the <body> tag is a descendant of the <body>, while the <body> tag is an ancestor of the <p> tag. Descendants (think ...