RMD063 — A style block's value was refused

A { … } hole becomes one CSS custom property, and a custom property's value may not contain a ; — that character is what separates declarations, so a value carrying one would become a second declaration on the element.

Measured through a server render and back: a value like red; position: fixed; width: 100vw came out of the round trip as real, applied declarations, on a page nothing else would have refused. So the value is not written at all and the declaration is dropped, which is the right way round — a missing border beats a full-viewport overlay somebody's record asked for.

The rule is asked of the TEXT, and that had to be measured to be got right: the check used to ask whether the value was a string before it became one, so { toString: () => "red; position: fixed" } went past it and came back off a server render as applied declarations.

The same code reports the other half of the rule — a hole takes a string or a finite number, and nothing else is written. true, {}, a function and NaN all become text a property cannot parse, so writing them would leave the declaration to fall back with nothing said. The types refuse them, so one arriving means the value reached the runtime through JavaScript that was not checked.

The value came from an expression, so it is fixed where that expression reads its data, not at the block. A hole is for a value the page computes; text that arrives from a record, a query string or a form belongs behind whatever validates it first.

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