diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 72c235b9..d7dd8494 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -43,8 +43,8 @@ jobs:
         if: steps.node-modules-cache.outputs.cache-hit != 'true'
         run: npm ci
 
-      - name: Run CSS lint
-        run: npm run lint:css
+      - name: Run lint suite
+        run: npm run lint
 
       - name: Build CSS
         run: npm run build:css
diff --git a/README.md b/README.md
index dfd6ce65..564c3f0e 100644
--- a/README.md
+++ b/README.md
@@ -84,13 +84,20 @@ the shared tokens in `css/tokens.css`. Install dependencies once and lean on the
 package scripts to keep formatting, linting, and generated output consistent:
 
 ```bash
-npm install          # install Prettier, Stylelint, and Tailwind toolchain
-npm run format       # format CSS/HTML/JS/MD with Prettier + tailwindcss plugin
-npm run lint:css     # enforce token usage and forbid raw hex colors
-npm run build:css    # rebuild css/tailwind.generated.css from tailwind.source.css
-npm run check:css    # CI-friendly guard that fails if tailwind.generated.css is dirty
+npm install               # install Prettier, Stylelint, and Tailwind toolchain
+npm run format            # format CSS/HTML/JS/MD with Prettier + tailwindcss plugin
+npm run lint              # run CSS, hex color, and inline-style guards in one pass
+npm run lint:css          # enforce token usage and forbid raw hex colors
+npm run lint:inline-styles # fail CI if inline style attributes or element.style usage slip in
+npm run build:css         # rebuild css/tailwind.generated.css from tailwind.source.css
+npm run check:css         # CI-friendly guard that fails if tailwind.generated.css is dirty
 ```
 
+Inline styles are intentionally blocked. `npm run lint:inline-styles` scans HTML
+and scripts for `style=` attributes, `element.style`, or `style.cssText` usage
+and will fail CI until offending markup is moved into the shared CSS/token
+system.
+
 The build command compiles Tailwind with `tailwind.config.cjs`, runs it through
 the PostCSS pipeline defined in `postcss.config.cjs` (for autoprefixing), and
 emits the purged, minified stylesheet at `css/tailwind.generated.css`. Commit the
diff --git a/package.json b/package.json
index 3e29befe..31ef208b 100644
--- a/package.json
+++ b/package.json
@@ -6,9 +6,10 @@
   "scripts": {
     "build:css": "npx tailwindcss -c tailwind.config.cjs -i css/tailwind.source.css -o css/tailwind.generated.css --minify",
     "format": "prettier --cache --write css/tailwind.source.css css/tokens.css \"docs/**/*.html\" tailwind.config.cjs README.md",
-    "lint": "npm run lint:css && npm run lint:hex",
+    "lint": "npm run lint:css && npm run lint:hex && npm run lint:inline-styles",
     "lint:css": "stylelint css/tailwind.source.css css/tokens.css",
     "lint:hex": "node scripts/check-hex.js",
+    "lint:inline-styles": "node scripts/check-inline-styles.mjs",
     "check:css": "npm run build:css && git diff --exit-code -- css/tailwind.generated.css",
     "test:visual": "npm run build:css && npx playwright test",
     "test:visual:update": "npm run build:css && cross-env UPDATE_VISUAL_BASELINES=1 npx playwright test",
diff --git a/scripts/check-hex.js b/scripts/check-hex.js
index d4d26b57..c0a7b181 100755
--- a/scripts/check-hex.js
+++ b/scripts/check-hex.js
@@ -1,6 +1,6 @@
 #!/usr/bin/env node
 
-const { spawnSync } = require('node:child_process');
+import { spawnSync } from "node:child_process";
 
 const SEARCH_PATTERN = '\\b#[0-9a-fA-F]{3,8}\\b';
 // Allow-list tokens and vector logos so brand assets can keep their baked colors.
diff --git a/scripts/check-inline-styles.mjs b/scripts/check-inline-styles.mjs
new file mode 100644
index 00000000..9cb9a01e
--- /dev/null
+++ b/scripts/check-inline-styles.mjs
@@ -0,0 +1,203 @@
+#!/usr/bin/env node
+
+import { readdir, readFile } from "node:fs/promises";
+import path from "node:path";
+import process from "node:process";
+import { fileURLToPath } from "node:url";
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+const repoRoot = path.resolve(__dirname, "..");
+
+const IGNORED_DIRS = new Set([
+  ".git",
+  "node_modules",
+  "vendor",
+  "torrent",
+  "dist",
+  "build",
+  ".next",
+  "out",
+  "coverage",
+  ".cache",
+  ".astro",
+  ".svelte-kit",
+  ".vercel",
+  "tmp",
+  "logs",
+]);
+
+const IGNORED_FILES = new Set([
+  "js/ui/styleSystem.js",
+  "css/tailwind.generated.css",
+  "js/webtorrent.min.js",
+  "js/webtorrent.min.js.map",
+  "scripts/check-inline-styles.mjs",
+  "sw.min.js",
+]);
+
+const TEXT_EXTENSIONS = new Set([
+  ".astro",
+  ".cjs",
+  ".html",
+  ".htm",
+  ".js",
+  ".jsx",
+  ".liquid",
+  ".mjs",
+  ".njk",
+  ".svelte",
+  ".svg",
+  ".ts",
+  ".tsx",
+  ".vue",
+]);
+
+const INLINE_STYLE_ATTR_REGEX = /<[^>]*\sstyle\s*=/gim;
+const DIRECT_STYLE_REGEX = /(?<!['"`])\.\s*style\b/gim;
+
+function toPosix(relPath) {
+  return relPath.split(path.sep).join("/");
+}
+
+function buildLineBreaks(content) {
+  const breaks = [];
+  let index = content.indexOf("\n");
+  while (index !== -1) {
+    breaks.push(index);
+    index = content.indexOf("\n", index + 1);
+  }
+  return breaks;
+}
+
+function getLineNumber(lineBreaks, index) {
+  let low = 0;
+  let high = lineBreaks.length;
+  while (low < high) {
+    const mid = Math.floor((low + high) / 2);
+    if (index <= lineBreaks[mid]) {
+      high = mid;
+    } else {
+      low = mid + 1;
+    }
+  }
+  return low + 1;
+}
+
+function getLineSnippet(content, index) {
+  const start = content.lastIndexOf("\n", index - 1) + 1;
+  let end = content.indexOf("\n", index);
+  if (end === -1) {
+    end = content.length;
+  }
+  return content.slice(start, end).trim();
+}
+
+function collectViolations(relPath, content) {
+  const lineBreaks = buildLineBreaks(content);
+  const results = [];
+
+  let match;
+
+  INLINE_STYLE_ATTR_REGEX.lastIndex = 0;
+  while ((match = INLINE_STYLE_ATTR_REGEX.exec(content))) {
+    const index = match.index;
+    results.push({
+      file: toPosix(relPath),
+      line: getLineNumber(lineBreaks, index),
+      label: "Inline style attribute",
+      snippet: getLineSnippet(content, index),
+    });
+  }
+
+  DIRECT_STYLE_REGEX.lastIndex = 0;
+  while ((match = DIRECT_STYLE_REGEX.exec(content))) {
+    const index = match.index;
+    const after = content.slice(DIRECT_STYLE_REGEX.lastIndex);
+    const isCssText = /^\s*\.\s*cssText/i.test(after);
+    results.push({
+      file: toPosix(relPath),
+      line: getLineNumber(lineBreaks, index),
+      label: isCssText ? "style.cssText usage" : "Direct .style usage",
+      snippet: getLineSnippet(content, index),
+    });
+  }
+
+  return results;
+}
+
+function shouldIgnore(relPath) {
+  const parts = relPath.split(path.sep);
+  if (parts.some((part) => IGNORED_DIRS.has(part))) {
+    return true;
+  }
+  const posixPath = toPosix(relPath);
+  if (IGNORED_FILES.has(posixPath)) {
+    return true;
+  }
+  return false;
+}
+
+function shouldCheckFile(relPath) {
+  const ext = path.extname(relPath).toLowerCase();
+  if (ext === "") {
+    return false;
+  }
+  return TEXT_EXTENSIONS.has(ext);
+}
+
+async function walk(dir, results) {
+  const entries = await readdir(dir, { withFileTypes: true });
+  for (const entry of entries) {
+    const fullPath = path.join(dir, entry.name);
+    const relPath = path.relative(repoRoot, fullPath);
+
+    if (shouldIgnore(relPath)) {
+      continue;
+    }
+
+    if (entry.isDirectory()) {
+      await walk(fullPath, results);
+      continue;
+    }
+
+    if (!entry.isFile()) {
+      continue;
+    }
+
+    if (!shouldCheckFile(relPath)) {
+      continue;
+    }
+
+    const content = await readFile(fullPath, "utf8");
+    const fileViolations = collectViolations(relPath, content);
+    results.push(...fileViolations);
+  }
+}
+
+async function main() {
+  const results = [];
+  await walk(repoRoot, results);
+
+  if (results.length > 0) {
+    console.error("\nInline style usage detected:\n");
+    for (const violation of results) {
+      console.error(
+        `${violation.file}:${violation.line} — ${violation.label}\n  ${violation.snippet}\n`
+      );
+    }
+    console.error(
+      "Inline styles are disallowed. Move styles into tokens, CSS, or styleSystem."
+    );
+    process.exitCode = 1;
+    return;
+  }
+
+  console.log("No inline style usage found.");
+}
+
+main().catch((error) => {
+  console.error("Failed to scan for inline styles.");
+  console.error(error);
+  process.exitCode = 1;
+});
diff --git a/tests/video-modal-zap.test.mjs b/tests/video-modal-zap.test.mjs
index bb6c20f1..e97639b6 100644
--- a/tests/video-modal-zap.test.mjs
+++ b/tests/video-modal-zap.test.mjs
@@ -11,7 +11,12 @@ class DummyElement {
       toggle: noop,
       contains: () => false,
     };
-    this.style = {};
+    Object.defineProperty(this, "style", {
+      configurable: true,
+      enumerable: true,
+      writable: true,
+      value: {},
+    });
     this.dataset = {};
     this.children = [];
   }