Which syntax defines a CSS custom property?

Which syntax defines a CSS custom property?

• A. --name: value;
• B. var(--name)
• C. name--: value
• D. $name: value

Answer: (A)

Defining a CSS custom property uses a name that begins with two hyphens, followed by a colon and the value. This two-dash prefix is what marks it as a custom property, so an example declaration would be --name: value;. The declaration ends with a semicolon and is placed inside a selector (often on :root for global scope). To actually use that value, you retrieve it with var(--name). The other options don’t define a custom property: var(--name) is how you read the value, not declare it; name--: value uses an invalid property name format; $name: value comes from CSS preprocessors like Sass, not vanilla CSS.

Defining a CSS custom property uses a name that begins with two hyphens, followed by a colon and the value. This two-dash prefix is what marks it as a custom property, so an example declaration would be --name: value;. The declaration ends with a semicolon and is placed inside a selector (often on :root for global scope). To actually use that value, you retrieve it with var(--name).

The other options don’t define a custom property: var(--name) is how you read the value, not declare it; name--: value uses an invalid property name format; $name: value comes from CSS preprocessors like Sass, not vanilla CSS.