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Web・UIデザイン

ウェブのアクセシビリティ監査(WCAG 2.2 AA)

AIBarsMITSkill の言語: 英語
ライセンス確認済みスクリプトなし低リスク
デモ実行記録 · claude-sonnet-5-5 · 2026年10月
Using the web-accessibility-audit skill, review this fictional markup and report findings with WCAG references, severity and fixes, and say what you could not check: (1) <div class="btn" onclick="save()">Save</div> (2) <input placeholder="Email"> with no label (3) a modal div that opens with no focus handling and no Escape key (4) <button><svg>...</svg></button> as an icon-only button (5) an error shown as red text "Invalid" under a field with no other cue (6) a sticky header 80px tall on a page with long forms.
Skill: web-accessibility-audit

Accessibility review: six fictional snippets (WCAG 2.2 AA)

Scope and assumptions: I reviewed only the markup and descriptions you gave me. The target is WCAG 2.2 AA. I assumed the form and modal belong to a key flow such as sign-up or settings. This is an engineering review, not a compliance statement.

Findings

ID Severity Snippet
A1 Blocker Clickable div
A2 Serious Input with no label
A3 Blocker Modal with no focus handling or Escape
A4 Serious Icon-only button
A5 Serious Error shown only as red text
A6 Serious 80px sticky header

A1. <div class="btn" onclick="save()">Save</div>: Blocker

  • WCAG: 2.1.1 Keyboard, 4.1.2 Name, Role, Value. 2.4.7 Focus Visible is also at risk.
  • Problem: A div is not focusable and has no button role. Keyboard and switch users can't reach it or activate it. Screen readers announce it as plain text.
  • Affects: Keyboard, screen reader, voice control and switch users.
  • Fix:
    <button type="button" class="btn" id="save">Save</button>
    
    Attach the handler with addEventListener. Keep a visible :focus-visible style.
  • Verify: Tab to it, then press Enter and Space. A screen reader should announce "Save, button".

A2. <input placeholder="Email"> with no label: Serious

  • WCAG: 1.3.1 Info and Relationships, 3.3.2 Labels or Instructions, 4.1.2. Also 1.3.5 Identify Input Purpose, and 1.4.3 if the placeholder color is pale.
  • Problem: The placeholder is not a reliable accessible name. It disappears on input, often has low contrast, and is not consistently exposed. Voice-control users can't target the field by name.
  • Affects: Screen reader, voice control, cognitive and low-vision users.
  • Fix:
    <label for="email">Email</label>
    <input id="email" name="email" type="email" autocomplete="email">
    
  • Verify: Clicking the label focuses the input. The accessibility tree shows the name "Email". The placeholder contrast needs measuring if you keep it.

A3. Modal div with no focus handling and no Escape: Blocker

  • WCAG: 2.1.1 Keyboard, 2.4.3 Focus Order, 4.1.2. Possibly 2.1.2 No Keyboard Trap, because focus can wander behind the overlay. 1.3.1 also applies if there is no dialog semantics.
  • Problem: Focus stays on the trigger, so keyboard users tab through the page behind the modal. Screen readers don't know a dialog opened. There is no keyboard way to close it.
  • Affects: Keyboard, screen reader and screen magnifier users.
  • Fix:
    • Prefer the native element: <dialog> opened with showModal(). It handles the focus trap, inert background and Escape.
    • If you use a custom div, add role="dialog" aria-modal="true" aria-labelledby="dlg-title".
    • Move focus into the dialog on open, and keep it inside while open.
    • Close on Escape.
    • Make the background inert.
    • Return focus to the trigger on close.
    • Give the dialog a visible, labeled close button.
  • Verify: Tab and Shift+Tab never leave the dialog. Escape closes it and focus returns to the trigger. A screen reader announces the dialog name on open.

A4. <button><svg>…</svg></button>: Serious

  • WCAG: 1.1.1 Non-text Content, 4.1.2. Also 2.5.3 Label in Name if there is visible text, and 1.4.11 Non-text Contrast for the icon.
  • Problem: The button has no accessible name. A screen reader says only "button". Voice control can't target it.
  • Affects: Screen reader and voice control users.
  • Fix:
    <button type="button" aria-label="Close">
      <svg aria-hidden="true" focusable="false">…</svg>
    </button>
    
    Visible text is better if there is room. If you add a tooltip, it must meet 1.4.13.
  • Verify: The accessibility tree shows a name that describes the action. The icon has at least 3:1 contrast against its background. Check the target is at least 24×24 CSS px (2.5.8).

A5. Red "Invalid" text as the only error cue: Serious

  • WCAG: 1.4.1 Use of Color, 3.3.1 Error Identification, 3.3.3 Error Suggestion, 4.1.3 Status Messages, 1.3.1. Also 1.4.3 for the red text.
  • Problem: Users who are colorblind or low-vision, or who use a screen reader, may not notice the error or know which field it belongs to. "Invalid" doesn't say what to fix. Red on white often fails 4.5:1 depending on the shade, and I can't tell from the description.
  • Affects: Colorblind, low-vision, screen reader and cognitive users.
  • Fix:
    <input id="email" aria-invalid="true" aria-describedby="email-err">
    <p id="email-err"><svg aria-hidden="true">…</svg> Enter an email like [email protected]</p>
    
    • Add an icon and a specific message.
    • Give the field a non-color cue such as a thicker border.
    • Announce the error through a live region or by moving focus to an error summary on submit.
  • Verify: View it in grayscale. A screen reader reads the error when the field is focused. Measure the text contrast.

A6. 80px sticky header on pages with long forms: Serious

  • WCAG: 2.4.11 Focus Not Obscured (Minimum), new in 2.2. Also 1.4.10 Reflow and 1.4.4 Resize Text, because 80px of fixed height takes a large share of a short or zoomed viewport.
  • Problem: When tabbing down a long form, focused fields can scroll under the header and be completely hidden. At 400% zoom the header may leave almost no room for content.
  • Affects: Keyboard users, low-vision users who zoom, and mobile landscape users.
  • Fix:
    html { scroll-padding-top: 96px; }  /* header height plus margin */
    :target, :focus { scroll-margin-top: 96px; }
    
    Also consider a shorter header, or making it non-sticky at small heights or high zoom:
    @media (max-height: 500px) { .site-header { position: static; } }
    
  • Verify: Tab through the whole form and confirm no focused element is fully hidden. Test at 200% and 400% zoom (320px width).

What I could not check

  • I didn't run any code, scanner, browser or screen reader. Everything above is from your description.
  • I couldn't measure color contrast: the actual colors weren't given. This covers the red error text, the placeholder, icons and focus indicators.
  • I couldn't judge the focus indicator, as no CSS was shown. I also couldn't check target sizes (2.5.8), zoom, reflow or text spacing.
  • I haven't seen the rest of the page, so I couldn't assess headings, landmarks, lang, the page title, a skip link, form grouping or autocomplete beyond the email field.
  • I can't tell whether the sticky header actually hides focus. That depends on scroll behavior and needs a live keyboard test.
  • Whether the labels, icon names and error messages are meaningful needs human judgment.
  • I didn't see the real save() flow, so I couldn't check status messages (4.1.3) or error prevention (3.3.4).

Top three fixes first

  1. Replace the div button with a real <button> (A1).
  2. Fix the modal: use <dialog> or add focus management, Escape, inert and focus return (A3).
  3. Add real labels and accessible errors to the form: label the input, give the icon button a name, and make errors text and programmatically tied to the field (A2, A4, A5).

What was good

  • You used a real <button> for the icon-only control, which is the right element. It only needs a name.
  • Visible "Save" text exists on the clickable div, so the label is already there for the real button.

Real run in an isolated folder with only this skill installed. Only the Skill and Read tools were enabled, so no command was run and no file was written. The scenario is fictional and the model had no access to the code. The markup is invented and the model lists what it could not check.

できること

キーボード、スクリーンリーダー、ズーム、音声操作を使う人の障壁を見つけ、それぞれに最小で正しい修正を提案します。6 つの段階で進めます。出発点となる自動スキャン、キーボードの確認、構造の確認(見出し、ランドマーク、ラベル、表)、見た目の確認(コントラスト、フォーカスの表示、200% と 400% のズーム、文字間隔)、スクリーンリーダーでの抜き取り確認、動的な挙動の確認(ダイアログ、メニュー、タブ、トースト、ルート遷移)です。チェックリストは「知覚可能・操作可能・理解可能・堅牢」で整理され、WCAG の達成基準を示し、2.2 で追加されたもの(フォーカスが隠れない、ドラッグ操作、ターゲットサイズ、一貫したヘルプ、重複入力の回避、アクセシブルな認証)も含みます。よくある不具合と修正(クリックできる div、ラベルのないコントロール、消されたフォーカスの枠、色だけのエラー、モーダルのフォーカス管理、不足しているライブリージョン)と ARIA の使い方のルールも挙げます。

報告の形式

各指摘に、ID、深刻度(ブロッカー、重大、中、軽微)、該当する基準、場所、影響を受ける人、コードによる修正、確認方法を付け、最後に、確認した点、確認していない点、最初に直すべき 3 件を示します。

向いている場面

公開前のページの見直し、キーボードやスクリーンリーダーの問題の修正、アクセシビリティレビューの準備。

補足とリスク

低リスク:スクリプトのない指示のみのパッケージで、ネットワーク接続やファイル書き込みはありません。これはエンジニアリング上の確認であり、法的な判断や認証ではなく、Skill はモデルに「このページは WCAG に準拠している」と言ってはならないと求めています。自動ツールが見つけられるのは問題の一部で、人の判断や、実際の支援技術を使った障害のある方によるテストが必要な基準もあります。コントラスト比は実際の色から計算する必要があり、推測してはいけません。動作中のページは見えず、確認できなかった点を挙げます。AIBars 制作のオリジナル(MIT)で、AI の支援で起草されています。コンプライアンスの用途に使う前に、アクセシビリティの専門家の確認を受けてください。架空のマークアップで 1 回試用しました。