picture-element

thedaviddias/Front-End-Checklist · Agent Skill

Checks the use of the <picture> tag with an <img> fallback, analyzing size, loading, and performance impact.

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Overview

PublisherthedaviddiasCommunity
Repositorythedaviddias/Front-End-Checklist ↗
Skill folderpicture-element
Stars74,050
Bundled files1
LicenseMIT
Last updatedMay 28, 2026
LinksSkill source ↗ · Repository ↗

Mozgi check

What we found in the skill files. Details come with a subscription.

Security
low risk · no obvious risks found — the full report shows the details
Compatibility
instructions only — works with most agents
Similar skills
37 similar skills found
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Installation

A skill is a folder with a SKILL.md file. Pick your agent and run the commands in a terminal (macOS, Linux or Git Bash on Windows) from your project root.

Copy the prompt into Claude, Codex or another assistant: it will review the skill and install it for you.

Install the “picture-element” skill from mozgi.io (https://mozgi.io/skills/picture-element/) for me.

1. Download the archive: https://mozgi.io/skills/picture-element/download
   If it fails, take the skill folder from the source: https://github.com/thedaviddias/Front-End-Checklist/tree/main/skills/picture-element
2. Read SKILL.md and the other files. Check the skill is safe: no hidden commands, no sending data elsewhere, no scripts doing something other than described. If anything looks suspicious, stop and tell me.
3. Put the “picture-element” folder into your agent's skills folder: .claude/skills/ for Claude Code, .agents/skills/ for Codex, .cursor/skills/ for Cursor, .gemini/skills/ for Gemini CLI. Inside the project if we are in one, otherwise in the home folder (~/.claude/skills/ etc.).
4. Make sure <skills folder>/picture-element/SKILL.md exists.
5. Briefly tell me what this skill does and offer to try it on my task.

If you cannot do a step yourself, tell me what to click or type.

Review the source files

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Read SKILL.md and any companion files before deciding whether to install. Click a file to preview it.

SKILL.md contents

Original author text · read-only

Use <picture> with an <img> fallback

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 carries alt
  • <source> elements are evaluated top-to-bottom; the first match wins
  • Use type="image/avif" and type="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 <picture> elements in this codebase. Verify: 1) Every <picture> has an <img> as its last child (required fallback). 2) The <img> has an alt attribute. 3) The <img> has width and height attributes. 4) <source> elements appear before the <img> child. 5) Each <source> has either a srcset attribute or a media attribute. 6) format-selecting <source> elements have a type attribute (type="image/avif", type="image/webp"). Flag any <picture> missing an <img> child or with <img> not as the last child.

Fix

For each <picture> element with issues: 1) If missing <img>: add <img src="{fallback-url}" alt="{description}" width="{w}" height="{h}"> as the last child. 2) If <img> is not last: move it to after all <source> elements. 3) If <source> elements lack type attributes for format selection: add type="image/avif" or type="image/webp". 4) Verify the <img src> points to a universally supported format (JPEG or PNG) as the ultimate fallback. Show the corrected <picture> markup.

Explain

Explain how the <picture> element works. Browsers evaluate <source> elements in document order and use the first one whose conditions match (type, media, srcset). The <img> element is the fallback for browsers that don't support <picture> (IE11) or don't support the source format. Without an <img> child, <picture> is invalid HTML and produces no output. The alt attribute must be on the <img>, not the <source> elements—it applies regardless of which source is selected.

Code Review

Review image assets, markup, and delivery configuration related to Use <picture> with an <img> 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

Frequently asked questions

What does the picture-element skill do?

Checks the use of the <picture> tag with an <img> fallback, analyzing size, loading, and performance impact.

How do I install picture-element?

Open the “Installation” block on this page and pick your agent — Claude Code, Codex, Cursor or Gemini CLI — for ready-made commands that copy the skill folder to the right place. Or copy the prompt from the “Via assistant” tab and let the assistant review and install the skill.

Which AI models work with picture-element?

Skills are plain Markdown instructions (the Agent Skills format), so picture-element works with any agent that reads SKILL.md: Claude Code, Codex, Cursor, Gemini CLI, GitHub Copilot, OpenCode and more. The model loads the instructions only when a task matches the skill's description.

Is picture-element free?

The skill is published openly by thedaviddias under the MIT license. The skill itself costs nothing — you only pay your AI provider for the tokens you use.

Is it safe to install skills?

A skill is a set of instructions your agent will follow, so read SKILL.md and its companion files before installing. Scripts in the skill folder only run if your agent runs them — keep an eye on what it does and do not grant unnecessary permissions.

How is a skill different from an MCP server or a plugin?

An MCP server or plugin gives the model new tools — code that runs and returns a result. A skill gives it knowledge and process: how to approach a task, which steps to follow and what good output looks like. It needs no server or API key.

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