Conditional CSS with styled tag

Author: mattoniCreated May 9, 2019Updated Nov 19, 2025

Labelsfeature: proposal 💬platform: react 🛠️cat: extend syntax ✍core team 🧬

Ask your Question

Is it possible to do something like the following?

const TopLevelList = styled.ul<{ dark?: boolean }>`
  border-top: 1px solid ${BrandColors.BORDER};
  margin-top: 0;

  ${props => props.dark && ({
    color: 'black',
  })}
`;

Typescript is giving the following error:

Argument of type '(props: { dark?: boolean | undefined; }) => false | { color: string; } | undefined' is not assignable to parameter of type 'string | number | CSSProperties | ((props: { dark?: boolean | undefined; }) => TLength)'.
  Type '(props: { dark?: boolean | undefined; }) => false | { color: string; } | undefined' is not assignable to type '(props: { dark?: boolean | undefined; }) => TLength'.
    Type 'false | { color: string; } | undefined' is not assignable to type 'TLength'.
      Type 'undefined' is not assignable to type 'TLength'.ts(2345)

Source: callstack/linaria

View original on GitHub View discussion on GitHub