# CSS: “grid-template-rows”: X is not a “grid-template-rows” value. > Canonical HTML version: https://rocketvalidator.com/html-validation/css-grid-template-rows-x-is-not-a-grid-template-rows-value > Attribution: Rocket Validator (https://rocketvalidator.com) > License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) The `grid-template-rows` property defines the size of each row in a CSS grid layout. The W3C validator checks that every value in the declaration conforms to the CSS Grid specification. When you see this error, the validator has encountered something it cannot parse as a valid track size. Common causes of this error include: - **Typos or invalid units** — writing `100 px` (with a space), `100pixels`, or `1 fr` instead of `1fr`. - **Using values from other properties** — for example, `flex`, `inline`, or `space-between` are not valid row track sizes. - **Incorrect function syntax** — missing commas in `repeat()`, providing wrong arguments to `minmax()`, or using unsupported functions. - **Missing units** — writing a bare number like `100` instead of `100px` (zero is the only number that doesn't require a unit). - **Using newer syntax not yet recognized** — some cutting-edge features like `subgrid` or the `masonry` value may trigger validation warnings depending on the validator's supported spec level. The `grid-template-rows` property accepts these valid value types: - **Length values**: `100px`, `5em`, `10rem`, `20vh` - **Percentages**: `50%`, `33.3%` - **Flexible lengths**: `1fr`, `2fr` - **Keywords**: `auto`, `min-content`, `max-content`, `none` - **Functions**: `repeat()`, `minmax()`, `fit-content()` - **Named lines**: `[row-start] 100px [row-end]` This matters for standards compliance and forward compatibility. While browsers may be lenient and ignore invalid values, relying on that behavior can lead to layouts that silently break. Valid CSS ensures your grid behaves predictably across all browsers. ## Examples ### Incorrect — invalid values ```html ``` ### Correct — valid track sizes ```html ``` ### Full working example ```html Grid template rows example
Row 1 — fixed 80px
Row 2 — between 150px and 1fr
Row 3 — auto-sized to content
``` ### Using `fit-content()` and named lines ```html ``` If your value looks correct but the validator still flags it, check whether you're using a very new CSS feature like `subgrid` or `masonry`. These may not yet be recognized by the validator even if some browsers support them. In that case, the warning can be acknowledged while keeping the value intentionally.