Helpful Links
- Ahmad Shadeed’s CSS Variables 101
- Lea Verou’s Custom properties with defaults: 3+1 strategies
@property: Next-gen CSS variables now with universal browser support
Vocabulary
Undefined
A variable that does not have a value yet.
Defined
A named variable with a value attached to it.
Declared
A named variable that potentially hasn’t been defined yet.
Placeholder or Override
An undefined variable used as a value with a fallback value.
Fallback or Default
An additional value added to the var() function to use if the first value is undefined.
Invalid Value
A value that at computed time does not match the type/context of the property it’s assigned to.
Private Variables
A naming convention for variables where the scope is limited to the element they are declared on.