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Agent skill

Picture Element

by thedaviddias in thedaviddias/Front-End-Checklist

A skill your agent uses when reviewing image assets, markup, and CDN or build transforms related to Use <picture with an <img fallback.

MITAuto-check passed

Install Picture Element

skills CLI
$ npx skills add thedaviddias/Front-End-Checklist --skill picture-element -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install thedaviddias/Front-End-Checklist picture-element --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/thedaviddias/Front-End-Checklist.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/picture-element .claude/skills/picture-element && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
picture-element
GitHub stars
74k
Token cost
~777 tokens
SKILL.md length
383 words
Files
2 (incl. references)
Skills in repo
390
Repo updated
First seen
Licence
MIT

At a glance

A skill your agent uses when reviewing image assets, markup, and CDN or build transforms related to Use <picture with an <img fallback.

  • Reviewing image assets
  • SKILL.md covers Quick Reference, Check, Fix and Explain, plus 1 more section
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
  • Build transforms related to Use <picture with an <img fallback

What it does

Picture Element is an agent skill from thedaviddias/Front-End-Checklist. Use when reviewing image assets, markup, and CDN or build transforms related to Use <picture with an <img fallback. Check encoded size, rendered size, loading strategy, and above-the-fold impact together.

Its SKILL.md is about 780 tokens, which your agent loads only when the skill is triggered. The skill folder holds 2 other files, including reference files (for example `references/rule.md`).

The repository describes itself as: 🗂 The essential checklist for modern web development, for humans and AI agents. The licence is MIT.

When your agent uses it

  • Reviewing image assets
  • Build transforms related to Use <picture with an <img fallback

Example prompts

  • “/picture-element”

What it can do on your machine

Read from SKILL.md and the folder at commit e8d14d0. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    No scripts in the folder and no shell commands in SKILL.md.

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    Links to these hosts (documentation or services it may open):

    • frontendchecklist.io

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Picture Element loads about 777 tokens when it runs, and up to ~2.2k if it reads all its reference files. Until then it costs about 56 tokens; SKILL.md has 383 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~56
When it runs · the whole SKILL.md, loaded when a task matches
~777
With references · SKILL.md plus every file in references/, read only if the agent opens them
~2.2k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from thedaviddias/Front-End-Checklist at commit e8d14d0, republished under its MIT licence (© thedaviddias). 383 words, ~777 tokens.

Download SKILL.mdSave it as .claude/skills/picture-element/SKILL.md (or your agent's skills folder). This skill also uses 1 other file; get the full folder from GitHub.
name
picture-element
description
Use when reviewing image assets, markup, and CDN or build transforms related to Use <picture> with an <img> fallback. Check encoded size, rendered size, loading strategy, and above-the-fold impact together.
metadata.category
images
metadata.priority
high
metadata.difficulty
beginner
metadata.estimatedTime
10
metadata.source
frontendchecklist.io
metadata.url
https://frontendchecklist.io/rules/images/picture-element

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.

Show full SKILL.md (130 more words)Show less

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/rules/images/picture-element

© thedaviddias, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 1 other file (references) in skills/picture-element of thedaviddias/Front-End-Checklist.

  • SKILL.md
  • references/rule.md

Open the folder on GitHubat commit e8d14d0

Compare with similar skills

Picture Element next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Picture Element compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Picture Element this skillthedaviddias/Front-End-Checklist74k—~777Automated safety check: PassMIT
Schema Markupalirezarezvani/claude-skills28k1 repos~2.9kAutomated safety check: PassMIT
Scaffold Elementremotion-dev/remotion63k—~202Automated safety check: PassCustom licence
Schema Markup Generatorsickn33/agentic-awesome-skills47k1 repos~2.1kAutomated safety check: PassMIT
Upload Element Previewsremotion-dev/remotion63k—~265Automated safety check: PassCustom licence
Remotion Markupremotion-dev/remotion63k2 repos~4.6kAutomated safety check: PassCustom licence

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Questions about Picture Element

What does Picture Element do?

A skill your agent uses when reviewing image assets, markup, and CDN or build transforms related to Use <picture with an <img fallback. Picture Element is an agent skill from thedaviddias/Front-End-Checklist. Use when reviewing image assets, markup, and CDN or build transforms related to Use <picture with an <img fallback.

When should I use Picture Element?

Picture Element fits situations like: reviewing image assets; build transforms related to Use <picture with an <img fallback.

How do I install Picture Element in Claude Code?

Run `npx skills add thedaviddias/Front-End-Checklist --skill picture-element -a claude-code`. Or copy the skill folder (skills/picture-element in thedaviddias/Front-End-Checklist) into .claude/skills/picture-element in your project. Claude Code loads it when a task matches its description.

How do I install Picture Element in Codex?

Run `npx skills add thedaviddias/Front-End-Checklist --skill picture-element -a codex`. Or copy the skill folder (skills/picture-element in thedaviddias/Front-End-Checklist) into .agents/skills/picture-element in your project. Codex loads it when a task matches its description.

Can I use Picture Element in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add thedaviddias/Front-End-Checklist --skill picture-element -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/picture-element, .gemini/skills/picture-element, .github/skills/picture-element and .opencode/skills/picture-element in your project.

What does Picture Element need to run?

SKILL.md names no scripts, command-line tools or credentials: Picture Element is instructions for the agent only.

Does Picture Element access the network?

SKILL.md names 1 domain. As links in the text: frontendchecklist.io. This is read from the text; nothing was executed.

Is Picture Element safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Picture Element use?

Picture Element is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Picture Element use?

About 777 tokens (SKILL.md is roughly 3.1k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 1.4k tokens, read only when the agent opens those files.

What are the alternatives to Picture Element?

Skills that share tags, products or a category with Picture Element: Schema Markup (alirezarezvani/claude-skills, 28k stars), Scaffold Element (remotion-dev/remotion, 63k stars), Schema Markup Generator (sickn33/agentic-awesome-skills, 47k stars) and Upload Element Previews (remotion-dev/remotion, 63k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Picture Element?

thedaviddias (a GitHub user) maintains it in thedaviddias/Front-End-Checklist, which has 74,421 GitHub stars. The repository holds 390 skills in this directory. The repository was last updated on October 6, 2026.

Source: thedaviddias/Front-End-Checklist on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.