Declared Stylesheet Not Found

A css: entry names a stylesheet that does not exist, so it was not copied into the output.

Q-5-29 — Declared Stylesheet Not Found

A css: entry names a stylesheet that does not exist, so it was not copied into the output. Every page linking it will request a file that is not there. The render continues; the (broken) link is still emitted.

What this means

A document or project can attach extra stylesheets to its HTML output with the css option:

# _quarto.yml
format:
  html:
    css:
      - styles.css

Quarto resolves each entry relative to the file that declares it: entries in _quarto.yml resolve against the project root, entries in a directory’s _metadata.yml against that directory, and entries in a document’s front matter against the document’s own directory. A leading / anchors the path at the project root from any of those places.

When the resolved file exists, Quarto copies it into the output tree and emits a depth-correct <link> on every page. This warning fires when the file does not exist: nothing is copied, and the <link> is emitted with the path exactly as you wrote it — visibly broken in the browser’s network tab rather than silently absent.

Common causes

• A typo in the path, or a file that was moved or renamed without updating the css entry.
• A path written relative to the wrong anchor — for example, a document in posts/2026/ declaring css: styles.css for a file that actually lives at the project root. From front matter that entry names posts/2026/styles.css; write /styles.css (or ../../styles.css) instead.
• A stylesheet that is generated later by a tool that has not run yet.

How to fix it

Check the path in the css entry against the anchor of the file that declares it, or add the missing stylesheet. If the stylesheet belongs to the project as a whole, declaring it once in _quarto.yml (project-root-relative) is usually clearer than repeating it per document.