1// ─── Section 1: Constants ───────────────────────────────────────────────────
2
3const SAFE_TAGS = new Set([
4 'blockquote', 'nav', 'a', 'input', 'textarea', 'select',
5 'pre', 'code', 'span', 'th', 'td', 'tr', 'li', 'label',
6 'button', 'hr', 'html', 'head', 'body', 'script', 'style',
7 'link', 'meta', 'title', 'br', 'img', 'svg', 'path', 'circle',
8 'rect', 'line', 'polyline', 'polygon', 'g', 'defs', 'use',
9]);
10
11// Per-check safe-tags override for the border (side-tab / border-accent)
12// rule. We intentionally re-allow <label> here because card-shaped clickable
13// labels (e.g. .checklist-item wrapping a checkbox + content) are one of the
14// canonical side-tab anti-pattern shapes and must be detected. The rule's
15// other preconditions (non-neutral color, width >= 2px on a single side,
16// radius > 0 or width >= 3, element size >= 20x20 in the browser path)
17// already filter out plain inline form labels so this does not introduce
18// false positives. See modern-color-borders.html for the test matrix.
19const BORDER_SAFE_TAGS = new Set(
20 [...SAFE_TAGS].filter(t => t !== 'label')
21);
22
23const OVERUSED_FONTS = new Set([
24 // Older monoculture (still ubiquitous):
25 'inter', 'roboto', 'open sans', 'lato', 'montserrat', 'arial', 'helvetica',
26 // Newer monoculture (the Anthropic-skill / Vercel / GitHub default wave):
27 'fraunces', 'instrument sans',
28 'geist', 'geist sans', 'geist mono',
29 'mona sans',
30 'plus jakarta sans', 'space grotesk', 'recoleta',
31]);
32
33// Brand-associated fonts: don't flag these as "overused" on the brand's own domains.
34// Keys are font names, values are arrays of hostname suffixes where the font is allowed.
35const GOOGLE_DOMAINS = [
36 'google.com', 'youtube.com', 'android.com', 'chromium.org',
37 'chrome.com', 'web.dev', 'gstatic.com', 'firebase.google.com',
38];
39const VERCEL_DOMAINS = ['vercel.com', 'nextjs.org', 'v0.app'];
40const GITHUB_DOMAINS = ['github.com', 'githubnext.com'];
41const BRAND_FONT_DOMAINS = {
42 'roboto': GOOGLE_DOMAINS,
43 'google sans': GOOGLE_DOMAINS,
44 'product sans': GOOGLE_DOMAINS,
45 'geist': VERCEL_DOMAINS,
46 'geist sans': VERCEL_DOMAINS,
47 'geist mono': VERCEL_DOMAINS,
48 'mona sans': GITHUB_DOMAINS,
49};
50
51function isBrandFontOnOwnDomain(font) {
52 if (typeof location === 'undefined') return false;
53 const allowed = BRAND_FONT_DOMAINS[font];
54 if (!allowed) return false;
55 const host = location.hostname.toLowerCase();
56 return allowed.some(suffix => host === suffix || host.endsWith('.' + suffix));
57}
58
59const GENERIC_FONTS = new Set([
60 'serif', 'sans-serif', 'monospace', 'cursive', 'fantasy',
61 'system-ui', 'ui-serif', 'ui-sans-serif', 'ui-monospace', 'ui-rounded',
62 '-apple-system', 'blinkmacsystemfont', 'segoe ui',
63 'inherit', 'initial', 'unset', 'revert',
64]);
65
66// WCAG large text thresholds are defined in points: 18pt normal text and
67// 14pt bold text. Browsers expose font-size in CSS pixels at 96px per inch.
68const WCAG_LARGE_TEXT_PX = 18 * (96 / 72);
69const WCAG_LARGE_BOLD_TEXT_PX = 14 * (96 / 72);
70
71// Serif faces that show up in italic-display heroes. The rule also fires when
72// the primary face is unknown but the stack ends in the generic `serif` token,
73// which catches custom/private faces with a serif fallback.
74const KNOWN_SERIF_FONTS = new Set([
75 'fraunces', 'recoleta', 'newsreader', 'playfair display', 'playfair',
76 'cormorant', 'cormorant garamond', 'garamond', 'eb garamond',
77 'tiempos', 'tiempos headline', 'tiempos text',
78 'lora', 'vollkorn', 'spectral',
79 'source serif pro', 'source serif 4', 'source serif',
80 'ibm plex serif', 'merriweather',
81 'libre caslon', 'libre baskerville', 'baskerville',
82 'georgia', 'times new roman', 'times',
83 'dm serif display', 'dm serif text',
84 'instrument serif', 'gt sectra', 'ogg', 'canela',
85 'freight display', 'freight text',
86]);
87
88export {
89 SAFE_TAGS,
90 BORDER_SAFE_TAGS,
91 OVERUSED_FONTS,
92 GOOGLE_DOMAINS,
93 VERCEL_DOMAINS,
94 GITHUB_DOMAINS,
95 BRAND_FONT_DOMAINS,
96 isBrandFontOnOwnDomain,
97 GENERIC_FONTS,
98 WCAG_LARGE_TEXT_PX,
99 WCAG_LARGE_BOLD_TEXT_PX,
100 KNOWN_SERIF_FONTS,
101};