FontWeightNotStyle [rule] v1.0.0

Font weight variation MUST be expressed via font-weight values (400, 510, 700) using a typeface that ships those weights — never via font-style: oblique or browser-synthesized faux-bold (font-weight: bold on a single-weight font).

Applies To

@community/type-html-artifact

Meta

• License: Apache-2.0
• License Provenance: package-authorship-claim

Severity

high

Remediation

• Load only the weights you actually use in @font-face (woff2 subset by weight).
• For variable fonts: declare font-weight: 100 900; in the @font-face range and let the single file handle all weights.
• Avoid font-weight: bold as a shorthand — use numeric values (700) so you know exactly what weight is requested.
• Check browser DevTools font panel for 'synthesized bold' warnings — these are hard failures.

Exceptions

• • Case: System font stacks
  • Allowed When: System-ui / -apple-system — the OS provides all weights natively; synthesis does not occur.

FontWeightNotStyle [rule] v1.0.0

Font weight variation MUST be expressed via font-weight values (400, 510, 700) using a typeface that ships those weights — never via font-style: oblique or browser-synthesized faux-bold (font-weight: bold on a single-weight font).

Applies To

@community/type-html-artifact

Meta

• License: Apache-2.0
• License Provenance: package-authorship-claim

Severity

high

Remediation

• Load only the weights you actually use in @font-face (woff2 subset by weight).
• For variable fonts: declare font-weight: 100 900; in the @font-face range and let the single file handle all weights.
• Avoid font-weight: bold as a shorthand — use numeric values (700) so you know exactly what weight is requested.
• Check browser DevTools font panel for 'synthesized bold' warnings — these are hard failures.

Exceptions

• • Case: System font stacks
  • Allowed When: System-ui / -apple-system — the OS provides all weights natively; synthesis does not occur.

Relations

related: [@community/rule-font-feature-settings, @community/rule-font-loading-fout-foit, @community/fact-optical-sizing, @community/anti-pattern-thin-weight-body, @community/example-atlantic-longform, @community/rule-body-readability, @community/principle-typography-hierarchy]

Rationale

Browser-synthesized bold works by algorithmically slanting and widening glyph outlines — it produces visibly distorted letterforms with uneven stroke weights and poor optical balance. Type designers spend years perfecting weight transitions; the browser's synthetic substitution destroys that work. Similarly, CSS font-style: italic on a sans-serif font that ships no italic causes the browser to slant upright glyphs into a fake oblique — missing the humanist curves of a true italic cut. The rule requires loading the actual weight file.

Applies To

@community/type-html-artifact

Meta

• License: Apache-2.0
• License Provenance: package-authorship-claim

Severity

high

Remediation

• Load only the weights you actually use in @font-face (woff2 subset by weight).
• For variable fonts: declare font-weight: 100 900; in the @font-face range and let the single file handle all weights.
• Avoid font-weight: bold as a shorthand — use numeric values (700) so you know exactly what weight is requested.
• Check browser DevTools font panel for 'synthesized bold' warnings — these are hard failures.

Exceptions

• • Case: System font stacks
  • Allowed When: System-ui / -apple-system — the OS provides all weights natively; synthesis does not occur.