CSS complexity

// CSS Complexity
// What in the CSS of the page costs bytes or style work and can go: embedded content, @import, empty
// rules, repeated selectors, unused @keyframes and complex selectors, read from the CSSOM of every
// stylesheet, and with
// fetch for a stylesheet of another origin whose rules the page cannot read
// https://webperf-snippets.net

(async () => {
  const SCRIPT = "CSS-Complexity";
  const MAX_ITEMS = 50;
  // The 90th percentile of the embedded content of a homepage in The CSS Selection 2026 (Project
  // Wallace): 90% of homepages embed less than this in all their CSS
  const EMBEDDED_P90_BYTES = 36632;
  // The 90th percentiles of !important (share of the declarations) and of @font-face rules
  const IMPORTANT_P90_PERCENT = 13;
  const FONT_FACE_P90 = 48;
  // The 90th percentile of the most complex selector of a homepage
  const SELECTOR_COMPLEXITY_P90 = 29;
  const MAX_COMPLEX_SELECTORS = 5;
  // Below this share of unique selectors, css-code-quality (Project Wallace) flags the duplication
  const MIN_SELECTOR_UNIQUENESS = 0.66;

  // @shared formatBytes
  function formatBytes(bytes) {
    if (bytes === null || bytes === undefined || Number.isNaN(bytes)) return "-";
    if (bytes === 0) return "0 B";
    const units = ["B", "KB", "MB", "GB"];
    const i = Math.max(0, Math.min(Math.floor(Math.log(bytes) / Math.log(1024)), units.length - 1));
    return (bytes / Math.pow(1024, i)).toFixed(1) + " " + units[i];
  }
  // @end-shared formatBytes

  // @shared ownRequestUrl
  // The URL a snippet requests when it reads a file of the page itself (fetch, a HEAD request,
  // new Image()). The fragment never reaches the server or the HTTP cache key, so the file still
  // comes from the cache, but it stays in the name of the Resource Timing entry of the request,
  // which is how isOwnRequest leaves these requests out of what the page loaded.
  function ownRequestUrl(url) {
    try {
      const parsed = new URL(url, location.href);
      if (!/^https?:$/.test(parsed.protocol)) return url;
      parsed.hash = "webperf-snippets";
      return parsed.href;
    } catch {
      return url;
    }
  }
  // @end-shared ownRequestUrl

  const plural = (n, one, many = `${one}s`) => `${n} ${n === 1 ? one : many}`;

  // Splits on a separator outside parentheses, brackets and strings: the declarations of a rule
  // (";"), or the selectors of a list (",")
  function splitTopLevel(text, separator) {
    const parts = [];
    let depth = 0;
    let quote = null;
    let start = 0;
    for (let i = 0; i < text.length; i++) {
      const c = text[i];
      if (quote) {
        if (c === "\\") i++;
        else if (c === quote) quote = null;
      } else if (c === '"' || c === "'") quote = c;
      else if (c === "(" || c === "[") depth++;
      else if (c === ")" || c === "]") depth--;
      else if (c === separator && depth === 0) {
        parts.push(text.slice(start, i));
        start = i + 1;
      }
    }
    parts.push(text.slice(start));
    return parts.map((p) => p.trim()).filter(Boolean);
  }

  // The declarations as written, from cssText: the CSSOM lists a shorthand as all its longhands in
  // style.length, and cssText joins them back
  const declarationsOf = (style) => splitTopLevel(style.cssText, ";");

  const FONT_TYPES = /^(font\/|application\/(x-)?font-|application\/vnd\.ms-fontobject)/;

  // The data: URLs of a declaration block, as the CSSOM serializes them: url("data:…")
  function embeddedOf(cssText, inFontFace) {
    const found = [];
    for (const [, raw] of cssText.matchAll(/url\("((?:[^"\\]|\\.)*)"\)/g)) {
      const url = raw.replace(/\\(["\\])/g, "$1");
      if (!/^data:/i.test(url)) continue;
      const type = url.slice(5).split(/[;,]/)[0].toLowerCase() || "text/plain";
      found.push({ type, bytes: url.length, font: inFontFace || FONT_TYPES.test(type) });
    }
    return found;
  }

  // --- Selector complexity, as css-analyzer counts it ------------------------------------------
  // Every part of a selector counts 1: type, class, id, attribute, pseudo-class, pseudo-element,
  // combinator, * and &. A vendor prefix and an attribute value count 1 more. :is(), :where(),
  // :not(), :has(), :matches() and :-webkit-any() add the complexity of the selectors they hold,
  // and :nth-child() that of its "of S" part, or 1 for its An+B. Those add every selector found in
  // their argument, at any depth, so :is(:is(.a)) is 4. Another pseudo with an argument adds 1 for
  // the list and the selectors in it, but :lang() and :nth-of-type() only 1.

  const SELECTOR_FUNCTIONS = new Set(["is", "where", "not", "has", "matches", "-webkit-any", "-moz-any"]);
  const total = (values) => values.reduce((a, b) => a + b, 0);
  // The complexities of the selectors of a list, and of every selector nested in them
  const selectorsIn = (text) => splitTopLevel(text, ",").flatMap((selector) => {
    const { complexity, nested } = analyzeSelector(selector);
    return [complexity, ...nested];
  });
  const complexityOf = (selectorText) => analyzeSelector(selectorText).complexity;

  // The complexity of a selector, and the complexities of the selectors nested in its pseudo-classes
  function analyzeSelector(selectorText) {
    const s = selectorText.trim();
    let complexity = 0;
    const nested = [];
    let i = 0;
    let afterCombinator = false;
    const readIdent = () => {
      const start = i;
      while (i < s.length) {
        if (s[i] === "\\") i += 2;
        else if (/[\w-]/.test(s[i]) || s.charCodeAt(i) > 127) i++;
        else break;
      }
      return s.slice(start, i);
    };
    // The text between the parenthesis at i and its match, after which i points
    const readGroup = (open, close) => {
      const start = i + 1;
      let depth = 0;
      let quote = null;
      for (; i < s.length; i++) {
        const c = s[i];
        if (quote) {
          if (c === "\\") i++;
          else if (c === quote) quote = null;
        } else if (c === '"' || c === "'") quote = c;
        else if (c === open) depth++;
        else if (c === close && --depth === 0) return s.slice(start, i++);
      }
      return s.slice(start);
    };
    while (i < s.length) {
      const c = s[i];
      if (/\s/.test(c)) {
        while (i < s.length && /\s/.test(s[i])) i++;
        // Whitespace between two compounds is the descendant combinator
        if (i < s.length && !">+~".includes(s[i]) && complexity > 0 && !afterCombinator) {
          complexity++;
          afterCombinator = true;
        }
        continue;
      }
      if (">+~".includes(c)) {
        complexity++;
        i++;
        afterCombinator = true;
        continue;
      }
      afterCombinator = false;
      if (c === "*" || c === "&") {
        complexity++;
        i++;
      } else if (c === "#" || c === ".") {
        i++;
        readIdent();
        complexity++;
      } else if (c === "[") {
        const inner = readGroup("[", "]");
        complexity += /=/.test(inner) ? 2 : 1;
      } else if (c === ":") {
        i += s[i + 1] === ":" ? 2 : 1;
        const name = readIdent().toLowerCase();
        complexity += name.startsWith("-") ? 2 : 1;
        if (s[i] === "(") {
          const arg = readGroup("(", ")").trim();
          const of = name === "nth-child" || name === "nth-last-child" ? arg.match(/\sof\s([\s\S]+)$/i) : null;
          if (SELECTOR_FUNCTIONS.has(name) || of) {
            const found = selectorsIn(of ? of[1] : arg);
            complexity += total(found);
            nested.push(...found);
          } else if (name === "nth-child" || name === "nth-last-child" || name === "nth-of-type" || name === "nth-last-of-type" || name === "lang") {
            complexity += arg ? 1 : 0;
          } else {
            const found = selectorsIn(arg);
            const own = splitTopLevel(arg, ",").map(complexityOf);
            complexity += 1 + total(own);
            nested.push(...found);
          }
        }
      } else if (/[\w-\\]/.test(c) || s.charCodeAt(i) > 127) {
        readIdent();
        complexity++;
      } else {
        i++;
      }
    }
    return { complexity, nested };
  }

  // The most frequent value, or the mean of the most frequent ones when they tie, as css-analyzer
  function modeOf(values) {
    const frequencies = new Map();
    for (const v of values) frequencies.set(v, (frequencies.get(v) ?? 0) + 1);
    let top = 0;
    for (const n of frequencies.values()) if (n > top) top = n;
    const tied = [...frequencies.entries()].filter(([, n]) => n === top).map(([v]) => v);
    return tied.length ? tied.reduce((a, b) => a + b, 0) / tied.length : 0;
  }

  const describeHost = (el) => el.localName + (el.id ? `#${el.id}` : el.classList[0] ? `.${el.classList[0]}` : "");

  // --- The stylesheets: of the document, adopted, of open shadow roots, and imported -----------

  // Each entry is a stylesheet of the page, or the URL of one to fetch, imported by a fetched one
  const sheets = [];
  const seenSheets = new Set();
  // A stylesheet a browser extension links to the page is not part of it. The <style> elements an
  // extension injects carry no such mark, so the page tells to measure without extensions.
  const EXTENSION_URL = /^(chrome|moz|safari-web)-extension:/i;
  let extensionCount = 0;
  const addSheet = (sheet, source) => {
    if (!sheet || seenSheets.has(sheet)) return;
    seenSheets.add(sheet);
    if (sheet.href && EXTENSION_URL.test(sheet.href)) {
      extensionCount++;
      return;
    }
    sheets.push({ sheet, source });
  };
  const addUrl = (href) => {
    if (seenSheets.has(href)) return;
    if (EXTENSION_URL.test(href)) {
      seenSheets.add(href);
      extensionCount++;
      return;
    }
    seenSheets.add(href);
    sheets.push({ href, source: href });
  };

  // A stylesheet of another origin loaded without CORS: its rules throw, but fetch can read it when
  // the server sends Access-Control-Allow-Origin, as a CDN often does. replaceSync parses it with
  // the same CSSOM, and drops @import, so the imports are read from the text and left out of it.
  async function fetchSheet(href) {
    try {
      const response = await fetch(ownRequestUrl(href));
      if (!response.ok) return null;
      const text = (await response.text()).replace(/\/\*[\s\S]*?\*\//g, "");
      const statements = text.match(/@import\s[^;]*;/gi) ?? [];
      const imports = statements
        .map((statement) => statement.match(/@import\s+(?:url\(\s*)?(["']?)([^"')\s;]+)\1/i)?.[2])
        .filter(Boolean)
        .map((url) => new URL(url, href).href);
      const sheet = new window.CSSStyleSheet({ baseURL: href });
      sheet.replaceSync(statements.reduce((css, statement) => css.replace(statement, ""), text));
      return { rules: sheet.cssRules, imports };
    } catch {
      return null;
    }
  }
  let styleIndex = 0;
  let adoptedIndex = 0;
  for (const sheet of document.styleSheets) addSheet(sheet, sheet.href || `<style> #${++styleIndex}`);
  for (const sheet of document.adoptedStyleSheets ?? []) addSheet(sheet, `adopted stylesheet #${++adoptedIndex}`);
  for (const el of document.querySelectorAll("*")) {
    const root = el.shadowRoot;
    if (!root) continue;
    const host = describeHost(el);
    for (const sheet of root.styleSheets) addSheet(sheet, sheet.href || `<style> in the shadow root of ${host}`);
    for (const sheet of root.adoptedStyleSheets ?? []) addSheet(sheet, `adopted stylesheet in the shadow root of ${host}`);
  }

  // --- Counting ----------------------------------------------------------------------------------

  const imports = [];
  const embeddedTypes = new Map();
  // Every selector of every rule, without its context (@media, @supports), as css-analyzer counts them
  const selectorCounts = new Map();
  // The complexity of every selector, and of each distinct one
  const complexities = [];
  const complexityBySelector = new Map();
  const keyframesDefined = new Set();
  const animationsUsed = new Set();
  let keyframesCount = 0;
  let fontFaceCount = 0;

  // An element of another namespace than HTML, SVG or MathML has a style attribute and no style
  const noteAnimations = (style) => {
    for (const name of (style?.animationName ?? "").split(",")) {
      const n = name.trim();
      if (n && n !== "none") animationsUsed.add(n);
    }
  };

  // Counts the declarations of a block, its !important and the animations it names
  function noteDeclarations(style, stats) {
    const declarations = declarationsOf(style);
    stats.declarationCount += declarations.length;
    stats.importantCount += declarations.filter((d) => /!\s*important$/i.test(d)).length;
    noteAnimations(style);
    return declarations;
  }

  function walk(rules, stats, sheetUrl) {
    for (const rule of rules) {
      if (rule instanceof window.CSSImportRule) {
        stats.importCount++;
        let href = rule.href;
        try {
          href = new URL(rule.href, sheetUrl).href;
        } catch {
          // keep the href as written
        }
        imports.push({ from: stats.source, href });
        addSheet(rule.styleSheet, href);
      } else if (rule instanceof window.CSSStyleRule) {
        const declarations = noteDeclarations(rule.style, stats);
        const nested = rule.cssRules?.length ?? 0;
        const selectors = splitTopLevel(rule.selectorText, ",");
        stats.ruleCount++;
        stats.selectorCount += selectors.length;
        for (const selector of selectors) {
          selectorCounts.set(selector, (selectorCounts.get(selector) ?? 0) + 1);
          const complexity = complexityBySelector.get(selector) ?? complexityOf(selector);
          complexityBySelector.set(selector, complexity);
          complexities.push(complexity);
        }
        if (declarations.length === 0 && nested === 0) stats.emptyRuleCount++;
        count(embeddedOf(rule.style.cssText, false), stats);
        if (nested) walk(rule.cssRules, stats, sheetUrl);
      } else if (window.CSSNestedDeclarations && rule instanceof window.CSSNestedDeclarations) {
        // The declarations of a style rule that follow a nested rule, or sit in a nested @media
        noteDeclarations(rule.style, stats);
        count(embeddedOf(rule.style.cssText, false), stats);
      } else if (rule instanceof window.CSSFontFaceRule) {
        fontFaceCount++;
        stats.declarationCount += declarationsOf(rule.style).length;
        count(embeddedOf(rule.style.cssText, true), stats);
      } else if (rule instanceof window.CSSKeyframesRule) {
        keyframesCount++;
        keyframesDefined.add(rule.name);
        for (const keyframe of rule.cssRules) {
          stats.declarationCount += declarationsOf(keyframe.style).length;
          count(embeddedOf(keyframe.style.cssText, false), stats);
        }
      } else if (rule.cssRules) {
        // @media, @supports, @layer, @container and the other rules that group rules
        walk(rule.cssRules, stats, sheetUrl);
      }
    }
  }

  function count(embedded, stats) {
    for (const { type, bytes, font } of embedded) {
      stats.embeddedBytes += bytes;
      stats.embeddedCount++;
      if (font) {
        stats.fontCount++;
        stats.fontBytes += bytes;
      }
      const t = embeddedTypes.get(type) ?? { type, count: 0, bytes: 0 };
      t.count++;
      t.bytes += bytes;
      embeddedTypes.set(type, t);
    }
  }

  const perSheet = [];
  // The list grows while it is read: each @import adds the sheet it imports
  for (let i = 0; i < sheets.length; i++) {
    const { sheet, href, source } = sheets[i];
    let rules = null;
    let read = "cssom";
    let fetchedImports = [];
    try {
      rules = sheet?.cssRules ?? null;
    } catch {
      // A stylesheet of another origin, loaded without CORS
    }
    const url = href ?? sheet?.href;
    if (!rules && url) {
      const fetched = await fetchSheet(url);
      if (fetched) {
        rules = fetched.rules;
        fetchedImports = fetched.imports;
        read = "fetched";
      }
    }
    if (!rules) {
      perSheet.push({ source, read: "unreadable" });
      continue;
    }
    const stats = { source, read, ruleCount: 0, selectorCount: 0, declarationCount: 0, importantCount: 0, emptyRuleCount: 0, embeddedBytes: 0, embeddedCount: 0, fontCount: 0, fontBytes: 0, importCount: 0 };
    walk(rules, stats, url || location.href);
    for (const imported of fetchedImports) {
      stats.importCount++;
      imports.push({ from: source, href: imported });
      addUrl(imported);
    }
    perSheet.push(stats);
  }

  // The animations of style attributes, in the document and in open shadow roots
  const roots = [document, ...[...document.querySelectorAll("*")].map((el) => el.shadowRoot).filter(Boolean)];
  for (const root of roots) for (const el of root.querySelectorAll("[style]")) noteAnimations(el.style);

  const read = perSheet.filter((s) => s.read !== "unreadable");
  const unreadable = perSheet.filter((s) => s.read === "unreadable");
  const sum = (key) => read.reduce((total, s) => total + s[key], 0);
  // Unique selectors over all selectors; 1 without selectors, since none repeats
  const selectorUniqueness = () => {
    const total = [...selectorCounts.values()].reduce((a, b) => a + b, 0);
    return total ? Math.round((selectorCounts.size / total) * 1000) / 1000 : 1;
  };
  const details = {
    stylesheetCount: perSheet.length,
    extensionCount,
    unreadableCount: unreadable.length,
    fetchedCount: perSheet.filter((s) => s.read === "fetched").length,
    ruleCount: sum("ruleCount"),
    selectorCount: sum("selectorCount"),
    declarationCount: sum("declarationCount"),
    embeddedBytes: sum("embeddedBytes"),
    embeddedCount: sum("embeddedCount"),
    embeddedTypes: [...embeddedTypes.values()].sort((a, b) => b.bytes - a.bytes || a.type.localeCompare(b.type)),
    importCount: sum("importCount"),
    emptyRuleCount: sum("emptyRuleCount"),
    selectorUniqueness: selectorUniqueness(),
    importantCount: sum("importantCount"),
    importantPercent: 0,
    fontFaceCount,
    keyframesCount,
    unusedKeyframes: [...keyframesDefined].filter((name) => !animationsUsed.has(name)).sort(),
    // A loop, not Math.max(...complexities): a spread of hundreds of thousands of values overflows the stack
    maxSelectorComplexity: complexities.reduce((max, c) => (c > max ? c : max), 0),
    commonSelectorComplexity: modeOf(complexities),
    complexSelectors: [...complexityBySelector.entries()]
      .map(([selectorText, complexity]) => ({ selectorText, complexity }))
      .sort((a, b) => b.complexity - a.complexity)
      .slice(0, MAX_COMPLEX_SELECTORS),
  };
  details.importantPercent = details.declarationCount ? Math.round((details.importantCount / details.declarationCount) * 1000) / 10 : 0;

  // --- Issues ------------------------------------------------------------------------------------

  const issues = [];
  for (const s of read.filter((s) => s.fontCount > 0)) {
    issues.push({
      code: "embedded-font",
      severity: "warning",
      message: `${s.source} embeds ${plural(s.fontCount, "font file")} as ${s.fontCount === 1 ? "a data: URL" : "data: URLs"} (${formatBytes(s.fontBytes)}). An embedded font downloads with the stylesheet, blocks rendering with it and cannot be cached apart from it: serve fonts as WOFF2 files, with font-display`,
      target: s.source,
    });
  }
  if (details.embeddedBytes > EMBEDDED_P90_BYTES) {
    issues.push({
      code: "embedded-content",
      severity: "warning",
      message: `The CSS embeds ${formatBytes(details.embeddedBytes)} in ${plural(details.embeddedCount, "data: URL")}, more than 90% of homepages (${formatBytes(EMBEDDED_P90_BYTES)}, The CSS Selection 2026). It downloads and parses with the stylesheet even when it is not shown: serve large images and fonts as files`,
    });
  }
  for (const { from, href } of imports) {
    issues.push({
      code: "import",
      severity: "warning",
      message: `${from} imports ${href} with @import: the browser only requests it after it downloads and parses ${from}. Link it from the HTML, or bundle it`,
      target: href,
    });
  }
  if (details.emptyRuleCount > 0) {
    issues.push({
      code: "empty-rules",
      severity: "info",
      message: `${plural(details.emptyRuleCount, "empty rule")}, with no declarations: bytes to download and selectors to match that style nothing`,
    });
  }
  if (details.selectorCount > 0 && details.selectorUniqueness < MIN_SELECTOR_UNIQUENESS) {
    const repeated = [...selectorCounts.entries()].filter(([, n]) => n > 1).sort((a, b) => b[1] - a[1]);
    issues.push({
      code: "duplicate-selectors",
      severity: "info",
      message: `Only ${Math.round(details.selectorUniqueness * 100)}% of the ${details.selectorCount} selectors are unique: the same selectors repeat across rules, which adds CSS to download and match. Some repeat inside @media on purpose; merge the others. Most repeated: ${repeated.slice(0, 3).map(([sel, n]) => `${sel} (${n})`).join(", ")}`,
    });
  }
  if (details.importantPercent > IMPORTANT_P90_PERCENT) {
    issues.push({
      code: "important-ratio",
      severity: "info",
      message: `${details.importantPercent}% of the declarations use !important, more than on 90% of homepages (${IMPORTANT_P90_PERCENT}%, The CSS Selection 2026): a sign of overrides on overrides, which make the CSS grow`,
    });
  }
  if (fontFaceCount > FONT_FACE_P90) {
    issues.push({
      code: "font-face-count",
      severity: "info",
      message: `${fontFaceCount} @font-face rules, more than on 90% of homepages (${FONT_FACE_P90}, The CSS Selection 2026). Run Webfont-Usage-Analyzer to see which faces load and which are never used`,
    });
  }
  for (const { selectorText, complexity } of details.complexSelectors.filter((c) => c.complexity > SELECTOR_COMPLEXITY_P90)) {
    issues.push({
      code: "selector-complexity",
      severity: "info",
      message: `${selectorText} has a complexity of ${complexity}, more than the most complex selector of 90% of homepages (${SELECTOR_COMPLEXITY_P90}, The CSS Selection 2026). Complexity counts the parts of a selector, not its cost: the CSS selector costs insight of the DevTools Performance panel measures how long matching takes`,
      target: selectorText,
    });
  }
  // A stylesheet that could not be read could use them
  if (unreadable.length === 0) {
    for (const name of details.unusedKeyframes) {
      issues.push({
        code: "unused-keyframes",
        severity: "info",
        message: `@keyframes ${name} is defined, and no animation of the stylesheets or of a style attribute uses it: CSS that never runs, unless JavaScript sets it later`,
        target: name,
      });
    }
  }
  if (unreadable.length > 0) {
    issues.push({
      code: "unreadable-stylesheets",
      severity: "info",
      message: `${plural(unreadable.length, "cross-origin stylesheet")} could not be read, by the page or with fetch (no Access-Control-Allow-Origin), so the counts are a lower bound: ${unreadable.map((s) => s.source).join(", ")}`,
    });
  }

  // --- Items, the heaviest sheets first ----------------------------------------------------------

  const items = perSheet
    .map((s) => (s.read === "unreadable" ? { source: s.source, read: s.read } : { source: s.source, read: s.read, ruleCount: s.ruleCount, embeddedBytes: s.embeddedBytes, importCount: s.importCount, importantCount: s.importantCount }))
    .sort((a, b) => (b.embeddedBytes ?? -1) - (a.embeddedBytes ?? -1) || (b.ruleCount ?? -1) - (a.ruleCount ?? -1));

  // --- Console -----------------------------------------------------------------------------------

  console.group("%c🎨 CSS Complexity", "font-weight: bold; font-size: 14px;");
  const readNotes = [details.fetchedCount && `${details.fetchedCount} read with fetch`, unreadable.length && `${unreadable.length} unreadable`].filter(Boolean);
  console.log(`Stylesheets: ${details.stylesheetCount}${readNotes.length ? ` (${readNotes.join(", ")})` : ""}`);
  console.log(`Rules: ${details.ruleCount} · Selectors: ${details.selectorCount} · Declarations: ${details.declarationCount}`);
  console.log(`Embedded content: ${formatBytes(details.embeddedBytes)} in ${plural(details.embeddedCount, "data: URL")}`);
  console.log(`@import: ${details.importCount} · Empty rules: ${details.emptyRuleCount}`);
  console.log(`Unique selectors: ${Math.round(details.selectorUniqueness * 100)}% · !important: ${details.importantCount} (${details.importantPercent}%)`);
  console.log(`Selector complexity: ${details.maxSelectorComplexity} at most, ${details.commonSelectorComplexity} the most common`);
  console.log(`@font-face: ${fontFaceCount} · @keyframes: ${keyframesCount}${details.unusedKeyframes.length ? ` (unused: ${details.unusedKeyframes.join(", ")})` : ""}`);
  if (items.length > 0) {
    console.table(
      items.map((i) => ({ Source: i.source, Read: i.read, Rules: i.ruleCount ?? "-", Embedded: formatBytes(i.embeddedBytes), "@import": i.importCount ?? "-", "!important": i.importantCount ?? "-" }))
    );
  }
  if (issues.length > 0) issues.forEach((i) => console.log(`[${i.severity}] ${i.message}`));
  else console.log("%c✅ No issues found", "color: #22c55e; font-weight: bold;");
  console.groupEnd();

  return {
    script: SCRIPT,
    status: "ok",
    count: perSheet.length,
    corsLimitedAnalysis: unreadable.length > 0,
    details,
    items: items.slice(0, MAX_ITEMS),
    issues,
  };
})();