# CSS: “letter-spacing”: X is not a “letter-spacing” value.

> Canonical HTML version: https://rocketvalidator.com/html-validation/css-letter-spacing-x-is-not-a-letter-spacing-value
> Attribution: Rocket Validator (https://rocketvalidator.com)
> License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

`letter-spacing` takes `normal` or a length such as `0.05em`, and the validator rejects anything else, including percentages like `1%`.

CSS Text Module Level 4 adds percentages to `letter-spacing` and resolves them against the font size, so `1%` is one hundredth of the font size. Only recent browser versions support this, and the validator's CSS checker doesn't recognize it. A browser without support ignores the declaration, and the text keeps whatever spacing it inherits.

The `em` unit gives the same result in every browser. `1em` is the element's font size, so `1%` becomes `0.01em` and `5%` becomes `0.05em`. The spacing still scales with the text.

Made-up keywords such as `wide` trigger the same message. Use `normal` to reset the spacing, `0` for no extra space, or a length like `0.05em` or `1px`. Negative lengths are allowed and pull the letters closer together.

## Invalid example

```html
<h1 style="letter-spacing: 1%;">Upcoming events</h1>
```

## Valid example

```html
<h1 style="letter-spacing: 0.01em;">Upcoming events</h1>
```