# CSS: “font-family”: X is an incorrect operator.

> Canonical HTML version: https://rocketvalidator.com/html-validation/css-font-family-x-is-an-incorrect-operator
> Attribution: Rocket Validator (https://rocketvalidator.com)
> License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

A CSS syntax error in your `font-family` declaration is using an invalid character or operator where the validator expects a comma-separated list of font names.

The `font-family` property expects font names separated by commas. A common mistake is using operators like `+`, `=`, or `/` between font names, or copying malformed font names from URLs (like Google Fonts link URLs where `+` replaces spaces). Font names with spaces must be wrapped in quotes.

For example, `font-family: Open+Sans` is invalid because `+` is not a valid CSS operator in this context. The correct form is `font-family: "Open Sans"`. Similarly, using `font-family: Arial / Helvetica` is invalid — a comma should separate fallback fonts.

## Invalid Example

```html
<p style="font-family: Open+Sans, sans-serif;">Hello</p>
```

## Fixed Example

```html
<p style="font-family: 'Open Sans', sans-serif;">Hello</p>
```

Double-check that your font names use **commas** as separators, **quotes** around names with spaces, and no stray characters like `+`, `/`, or `=`.