Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add yuusakuri/agent-skills --skill modern-web-guidancegit clone --depth 1 https://github.com/yuusakuri/agent-skillsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/yuusakuri/agent-skills/modern-web-guidance)<a href="https://agentmods.dev/skills/yuusakuri/agent-skills/modern-web-guidance"><img src="https://agentmods.dev/badge/skills/yuusakuri/agent-skills/modern-web-guidance/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/yuusakuri/agent-skills/modern-web-guidance"><img src="https://agentmods.dev/badge/skills/yuusakuri/agent-skills/modern-web-guidance.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00233 | $0.01291 |
| Opus 5 | $0.00117 | $0.00646 |
| Sonnet 5 | $0.00047 | $0.00258 |
| Haiku 4.5 | $0.00023 | $0.00129 |
Grade A, and why
modern-web-guidance scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 11d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
This is a copy
100% identical to modern-web-guidance — 33 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 115 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Modern Web Guidance
A skill to search for specific web development use cases and retrieve their corresponding best practice guides.
When to use
Must use this skill:
- At the start of implementing any web feature.
- Before creating a new component, to check if a standardized pattern already exists.
- To avoid implementing ad-hoc solutions or loading large dependencies unnecessarily.
Usage Instructions
Step 1. Search Use Cases
Search with an action-oriented query summarizing what you want to achieve using the search command. Run modern-web-guidance directly with npx.
npx -y modern-web-guidance@latest search "<query>" --skill-version 2026_05_16-c5e78707
Example Output:
[
{
"id": "optimize-image-priority",
"description": "Optimize the loading priority of Largest Contentful Paint (LCP) candidate images.",
"category": "performance",
"featuresUsed": [ "Fetch priority" ],
"tokenCount": 985,
"similarity": 0.7289
},
{
"id": "defer-rendering-heavy-content",
"description": "Reduce rendering times in content-heavy web pages by deferring rendering for offscreen content.",
"category": "performance",
"featuresUsed": [ "content-visibility", "hidden=\"until-found\"" ],
"tokenCount": 1250,
"similarity": 0.6961
}
]
Note: If search results are vague, return no matches, or show low similarity scores, run the
listcommand to browse all guides:npx -y modern-web-guidance@latest list
Step 2. Retrieve Best Practices
Once you have a relevant id from the search results, call this script using the retrieve command to get the full guide. You can pass multiple IDs separated by commas.
npx -y modern-web-guidance@latest retrieve "<id>"
Example Output:
The markdown content of the guide describing implementation steps...
Using npx
- IMPORTANT: on Windows, using
npxmay fail. Usenpx.cmd ...instead. - Network access is required for fetching npm packages needed by the task.
- If the
npx -y modern-web-guidance…command hangs, you may be offline. Try running again in offline mode:npx --offline …. - The
--skill-versionflag is used to determine if this SKILL.md is out of date. If it is, a warning message is logged to stderr.
What ships with it
60 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
- guides/accessibility/accessibility.md 24 KB
- guides/accessibility/accessible-error-announcement.md 6.9 KB
- guides/built-in-ai/language-detection.md 3.5 KB
- guides/built-in-ai/language-model.md 7.1 KB
- guides/built-in-ai/prompt-api.md 7.1 KB
- guides/built-in-ai/summarizer.md 5.9 KB
- guides/built-in-ai/translator.md 5.4 KB
- guides/canvas/apply-webgl-shaders.md 10.0 KB
- guides/canvas/export-html-media-from-canvas.md 11 KB
- guides/canvas/expose-canvas-content-to-browser-features.md 15 KB
- guides/canvas/interactive-content-in-3d-scenes.md 14 KB
- guides/css-layout/animate-to-intrinsic-sizes.md 5.3 KB
- guides/css-layout/calculate-with-intrinsic-sizes.md 9.6 KB
- guides/css-layout/css-layout.md 20 KB
- guides/css-layout/design-token-reactivity.md 5.8 KB
- guides/css-layout/fluid-scaling.md 3.0 KB
- guides/css-layout/overflow-clipping-control.md 8.0 KB
- guides/css-layout/size-aware-styling.md 2.9 KB
- guides/css/adapt-scrollbar-to-contrast-preferences.md 3.5 KB
- guides/css/child-state-based-styling.md 4.8 KB
- guides/css/complex-shapes.md 3.5 KB
- guides/css/component-specific-light-dark-theme.md 9.3 KB
- guides/css/content-based-styling.md 5.2 KB
- guides/css/css.md 27 KB
- guides/css/customize-scrollbar-color-and-thickness.md 2.4 KB
- guides/css/dark-mode.md 15 KB
- guides/css/dynamic-sibling-styling.md 3.6 KB
- guides/css/highlight-text-ranges.md 5.4 KB
- guides/css/interactive-content-reveal.md 5.1 KB
- guides/css/reduce-style-repetition.md 3.9 KB
- guides/css/shaped-cutouts.md 7.0 KB
- guides/css/soft-edge-content-fade.md 2.6 KB
- guides/css/style-parent-with-has.md 6.0 KB
- guides/css/visually-texture-content.md 3.7 KB
- guides/datetime/calculate-event-differentials.md 4.4 KB
- guides/datetime/capture-location-agnostic-data.md 3.6 KB
- guides/datetime/coordinate-global-events.md 3.5 KB
- guides/datetime/format-human-readable-durations.md 4.2 KB
- guides/datetime/manage-recurring-intervals.md 3.3 KB
- guides/datetime/model-partial-time-concepts.md 4.2 KB
- guides/datetime/stabilize-reactive-state.md 3.5 KB
- guides/datetime/support-global-calendar-systems.md 5.7 KB
- guides/forms/animated-select-picker.md 7.8 KB
- guides/forms/autofill-address-form.md 4.1 KB
- guides/forms/autofill-highlight-inputs.md 2.3 KB
- guides/forms/autofill-payment-form.md 8.5 KB
- guides/forms/autofill-sign-in-form.md 9.9 KB
- guides/forms/autofill-sign-up-form.md 11 KB
- guides/forms/brand-consistent-forms.md 8.3 KB
- guides/forms/branded-select-styling.md 5.5 KB
- guides/forms/custom-select-picker-layouts.md 5.0 KB
- guides/forms/form-fields-automatically-fit-contents.md 5.8 KB
- guides/forms/forms.md 14 KB
- guides/forms/required-field-feedback.md 6.8 KB
- guides/forms/rich-media-picker.md 6.6 KB
- guides/forms/select-menu-interaction.md 5.6 KB
- guides/forms/validate-input-after-interaction.md 8.6 KB
- guides/html/custom-button-actions.md 7.2 KB
- guides/html/html.md 18 KB
- guides/html/move-dom-element-without-losing-state.md 2.5 KB
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 11d ago First seen · 115 lines · 233 tokens per session scan A 0e7aae3cc355
modern-web-guidance is a skill published in the GitHub repository yuusakuri/agent-skills (2 stars, last pushed 4d ago), licensed MIT. It adds 233 tokens to every session and 1,291 once invoked, about $0.0012 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to modern-web-guidance, differing in 33 lines, and is treated as a copy.
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