Use with an fallback
SkillMediaPicture-element is a skill for reviewing image assets on web pages. It checks markup that uses <picture> with an <img> fallback, along with CDN or build transforms, and evaluates encoded size, rendered size, loading strategy, and above-the-fold impact together.
Available today. Use it from your connected AI after setup.
No other account needed.
Have the image assets, markup, and CDN or build transform details for the page to review.
Then ask your AI: use the Use with an fallback skill
What your AI can do with it
- Review markup that uses <picture> with an <img> fallback
- Check CDN or build transforms applied to image assets
- Measure encoded size of image files
- Measure rendered size of images on the page
- Evaluate loading strategy of image assets
- Assess above-the-fold impact of images on page speed
Getting started
- Have the image assets, markup, and CDN or build transform details for the page to review.
- Add the picture-element skill to the agent's available skills.
- Ask the agent to review the images, and it will check encoded size, rendered size, loading strategy, and above-the-fold impact together.
What this skill tells your AI
The instructions your AI receives, as published by thedaviddias/front-end-checklist in skills/picture-element/SKILL.md and read by ahel’s review.
A <picture> without an <img> fallback renders nothing in browsers that don't support <picture> (IE11) or don't support any of the <source> formats. The <img> child is also where alt, width, height, loading, and fetchpriority attributes live—these apply regardless of which source the browser selects.
Quick Reference
- Every
<picture>must end with an<img>element—it is the required fallback and carriesalt <source>elements are evaluated top-to-bottom; the first match wins- Use
type="image/avif"andtype="image/webp"on<source>for format selection - The
<img src>should point to a JPEG or PNG—the universal fallback for all browsers
Check
Scan all elements in this codebase. Verify: 1) Every has an as its last child (required fallback). 2) The has an alt attribute. 3) The has width and height attributes. 4) elements appear before the child. 5) Each has either a srcset attribute or a media attribute. 6) format-selecting elements have a type attribute (type="image/avif", type="image/webp"). Flag any missing an child or with not as the last child.
Fix
For each element with issues: 1) If missing : add as the last child. 2) If is not last: move it to after all elements. 3) If elements lack type attributes for format selection: add type="image/avif" or type="image/webp". 4) Verify the points to a universally supported format (JPEG or PNG) as the ultimate fallback. Show the corrected markup.
Explain
Explain how the element works. Browsers evaluate elements in document order and use the first one whose conditions match (type, media, srcset). The element is the fallback for browsers that don't support (IE11) or don't support the source format. Without an child, is invalid HTML and produces no output. The alt attribute must be on the , not the elements—it applies regardless of which source is selected.
Code Review
Review image assets, markup, and delivery configuration related to Use with an fallback. Flag exact files or components where format choice, sizing, or loading behavior violates the rule, and describe how to confirm the fix in DevTools.
For full implementation details, code examples, and framework-specific guidance,
see references/rule.md.
Rule page: https://frontendchecklist.io/en/rules/images/picture-element
Signals
- GitHub stars
- 74k
- Forks
- 7k
- Last commit
- Aug 2026
Questions
- When should this skill be used?
- Use it when reviewing image assets, markup, and CDN or build transforms related to using <picture> with an <img> fallback.
- What does it check?
- It checks encoded size, rendered size, loading strategy, and above-the-fold impact together rather than in isolation.
Advanced
- Item type
- skill
- Key
picture-element- Source
- github.com/thedaviddias/front-end-checklist