Use when applies to all CSS layout rules. Check `width`, `min-width`, fixed pixel values on containers, `overflow`, `white-space`, and `word-break` properties. Use when auditing responsive design or WCAG 2.1 Level AA compliance. Test at 320px viewport width and at 400% browser zoom.
インストールする前に、エージェントに与えられる指示の中身を確認できます。
Low-vision users who cannot read at standard zoom levels increase browser zoom to 200–400%. At these zoom levels, a 1280px-wide page becomes effectively 320px wide. If elements overflow the viewport, users must scroll both vertically and horizontally to read content — this is exhausting and error-prone with a screen magnifier. WCAG 2.1 SC 1.4.10 (Reflow) specifically addresses this, requiring that all content is available without two-dimensional scrolling at 400% zoom.
width: 100vw not accounting for scrollbar width, long unbreakable strings, white-space: nowrapmax-width: 100% on images and media, overflow-wrap: break-word on text containers, and fluid layout unitsTest the page at a 320px CSS viewport width (equivalent to 400% browser zoom on a 1280px screen). Look for horizontal scrollbars or content overflowing outside the viewport. Specifically check: (1) elements with fixed width values in px that exceed the viewport; (2) min-width values that prevent shrinking; (3) images or media without max-width: 100%; (4) white-space: nowrap on text that causes overflow; (5) width: 100vw on elements (scrollbar width causes overflow); (6) long URLs or unbreakable strings in content areas.
(1) Replace fixed width: Npx on layout containers with max-width: Npx plus width: 100%. (2) Add max-width: 100% and height: auto to all images and media. (3) Apply overflow-wrap: break-word (with fallback word-wrap: break-word) to text containers that may contain long strings. (4) Replace width: 100vw with width: 100% on full-width elements (avoid scrollbar overflow). (5) Use CSS Grid or Flexbox with flex-wrap: wrap for multi-column layouts. (6) For data tables, wrap in a scrollable container: overflow-x: auto on the table wrapper, not the page body.
WCAG 2.1 SC 1.4.10 (Reflow, Level AA) requires that content does not require two-dimensional scrolling when displayed at a width of 320 CSS pixels or a height of 256 CSS pixels. This corresponds to 400% zoom on a 1280×1024 display. Exceptions are made for content that requires two-dimensional layout for usage (e.g., data tables, map interfaces, video). For all other content — body text, navigation, forms, images — horizontal scrolling is a barrier for screen magnification users who cannot see the full page width.
Review stylesheets, component styles, and responsive states related to Prevent horizontal scrolling. Flag exact selectors, declarations, or breakpoints that violate the rule in the rendered UI.
For full implementation details, code examples, and framework-specific guidance,
see references/rule.md.
Rule page: https://frontendchecklist.io/rules/css/horizontal-scroll
まだレビューはありません。使ってみた感想をお寄せください。
概要と使いどころ
Use when reviewing templates, rendered HTML, or shared components related to Create a custom 404 error page. Validate the final browser-facing markup, not just the source framework abstraction.
日本語の概要は準備中です。原文の説明を表示しています。
Use when auditing metadata, crawlability, structured data, or indexability related to Create a dedicated About page. Verify the rendered HTML and HTTP response rather than relying only on source files.
日本語の概要は準備中です。原文の説明を表示しています。
Use when reviewing component libraries, page flows, or CI pipelines that need repeatable accessibility checks. Automated testing is strongest at catching structural and attribute-level issues; it does not replace keyboard, screen reader, and manual UX testing.
日本語の概要は準備中です。原文の説明を表示しています。
Use when reviewing sign-in, sign-up, MFA, CAPTCHA, recovery, and re-auth flows. Evaluate the full authentication path, including error handling and backup methods, not just the primary login form.
日本語の概要は準備中です。原文の説明を表示しています。
Use when reviewing templates, rendered HTML, or shared components related to Make notifications accessible. Validate the final browser-facing markup, not just the source framework abstraction.
日本語の概要は準備中です。原文の説明を表示しています。
Use when reviewing rendered HTML, interactive components, or design-system patterns related to Use semantic table markup for screen readers. Check native semantics first, then inspect keyboard behavior, focus flow, accessible names, and screen-reader output where relevant.
日本語の概要は準備中です。原文の説明を表示しています。