HTML: the Root Element

What is Root Element

• Root element of HTML is the element represented by the html tag.
• Root element of XML may be other, depending on the XML. e.g. root element of SVG is represented by the svg tag. 〔see Practical SVG Tutorial〕
• Root element of Atom Webfeed is feed.

Why is Root Element Important

It's important because many CSS's meaning refers to it.

For example:

• length unit rem refers to root element.
• position property refers to root element.

• CSS: Length Units
• CSS: Create Layer (position:absolute)

CSS Syntax for Root Element

In CSS, the root can be specified by:

:root

For example, make all text red:

:root { color: red; }

This is often used when using CSS variables.

〔see CSS: Variable (Custom Property)〕