How to use the Avoid Intrusive Interstitials agent skill

What the interstitials skill makes the agent do

When the skill is installed, the agent looks at your CSS and JavaScript for modals, overlays, cookie banners, newsletter sign-up dialogs and promotional pop-ups. It looks for elements using position: fixed or position: absolute with a large z-index that cover a significant part of the viewport, backdrop overlays, and scripts that show a dialog on page load or shortly after.

For each suspect element, the skill asks five questions: does it appear on load or within a few seconds, does it cover more than a small part of the main content on screens narrower than 600px, is there a visible close button with an accessible name, can Escape close it, and does focus move into the dialog on open and return to the trigger on close. Dialogs that fail any check are flagged, and the agent suggests alternatives such as sticky banners, inline content or slide-in panels that leave the main content visible.

Install the interstitials skill

Download the ZIP for this skill from this page and unzip it. For a personal setup, put the unzipped skill folder inside ~/.claude/skills/. To limit it to one project, put it inside that project's .claude/skills/ folder instead.

If you use the Claude apps, you can upload the skill instead. Go to Settings, then Capabilities, then Skills, and upload it there.

• Personal: ~/.claude/skills/
• Single project: .claude/skills/ in the project root
• Claude apps: Settings → Capabilities → Skills

Trigger the skill with natural requests

You do not need a special command. Describe the task in plain language, and mention the kind of element you care about. The skill's description covers modals, overlays, pop-ups, cookie banners, newsletter dialogs and promotional overlays, so requests that name these are the most likely to load it.

Ask about the page you are reviewing and say what matters to you, such as mobile experience, SEO or keyboard access. The skill considers both SEO impact and WCAG focus management.

• Check our newsletter pop-up for intrusive interstitial problems.
• Review the cookie banner CSS and JavaScript before we launch.
• Does our promo overlay block content on mobile? Check the CSS breakpoints.
• Audit our modal dialogs for focus trapping and Escape-key closing.

What to provide and what to expect back

The skill lists no required tools, runs no scripts and uses no network access. Give the agent the stylesheets, components and scripts that render your pop-ups, plus any responsive breakpoints that affect them. The skill asks the agent to flag exact selectors, declarations or breakpoints that break the rule in the rendered UI, so the more specific the code you share, the more specific the findings.

Expect a list of flagged dialogs with the failed check for each, and fixes such as a smaller sticky banner, an inline block, or an accessible dialog with role='dialog', aria-modal='true', aria-labelledby, a focus trap, Escape handling and focus return. The skill is a review aid, so verify findings in the browser before changing code.

Safety notes: scripts and network

According to the skill's listing, it runs no scripts and uses no network. It only gives the agent written guidance to read your code and report on it. That still means the agent reads whatever code you share with it, so follow your normal policy for sharing source code with an AI tool.

The skill does not decide legal questions. It gives general guidance on cookie consent and age checks but does not confirm what local law requires. Check those requirements with the people responsible for compliance.

Tips for better results

Share the real markup and styles of the pop-up, not a description, because the checks depend on exact position, z-index and breakpoint values. Include the mobile breakpoint you use, since the skill tests coverage on screens narrower than 600px.

Ask for one dialog at a time when the page has several overlays. Treat exempt cases carefully: the skill's guidance treats legally required notices, age verification and login walls for gated content as exceptions, so explain which pop-up is which.