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Theme file has no layer boundary markers

theme
A theme: entry names an .scss file that contains none of the /*-- scss:... --*/ layer boundary markers Quarto needs to merge it into the Bootstrap bundle.

Q-14-7 — Theme File Has No Layer Boundary Markers

A theme: entry names an .scss file that contains none of the /*-- scss:... --*/ layer boundary markers Quarto needs to merge it into the Bootstrap bundle.

What this means

A custom theme file is not compiled on its own. Quarto splits it into layers and merges each layer into the matching section of the Bootstrap bundle: variables go before Bootstrap’s defaults so they take precedence, rules go after Bootstrap’s rules so they override them. The split is driven by comment markers in the file:

/*-- scss:defaults --*/
$primary: #2c5f8a;

/*-- scss:rules --*/
.sidebar { border-right: 1px solid $primary; }

The named file has none of these markers, so Quarto cannot tell which section anything belongs to. The render stops with this error instead of silently dropping the theme.

Why this happens

Common causes:

  • A plain CSS or SCSS file listed under theme:. A stylesheet that only contains rules belongs under css:, which links it as is, or needs a /*-- scss:rules --*/ marker at the top to become a theme layer.
  • A marker with the wrong spelling. The marker must be exactly /*-- scss:<layer> --*/, where <layer> is one of uses, functions, defaults, mixins, or rules.
  • A file that was meant to be @imported from another theme file rather than listed directly.

How to fix

  • Add a marker before the first line of the file: /*-- scss:defaults --*/ for variable assignments, /*-- scss:rules --*/ for CSS rules. A file can have several sections in any order.
  • If the file is a finished stylesheet with no Sass in it, move it from theme: to css:.