Disallow unknown custom properties.
a { color: var(--foo); }
/** ↑
* This custom property */
a { color: var(--foo, var(--bar)); }
/** ↑
* And this one */
This rule considers custom properties defined within the same source to be known.
The message
secondary option can accept the arguments of this rule.
The following patterns are considered problems:
a { color: var(--foo); }
a { color: var(--foo, var(--bar)); }
The following patterns are not considered problems:
a { --foo: #f00; color: var(--foo); }
a { color: var(--foo, #f00); }
a { --foo: #f00; color: var(--bar, var(--foo)); }
@property --foo { syntax: "<color>"; inherits: false; initial-value: #f00; }
a { color: var(--foo); }