modern-web

modern-web is a skill for Claude Code, Codex from fmind/dot. It costs 36 tokens per session (722 once invoked), scanned A, original, MIT.

A set of guidance for using modern HTML, CSS, JavaScript, and browser APIs, with advice about which browsers support each feature. It helps coding agents choose standard web features and avoid unnecessary libraries or old compatibility code.

In plain words
What is it for?
Use it when building or updating front-end interfaces, choosing native browser APIs, checking compatibility, or modernizing web code.
Why use it?
It reduces the risk of using outdated techniques or browser features that do not work in the intended browsers.

Skill for Claude CodeCodex

Install

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.

agentmods
npx agentmods add skills/fmind/dot/modern-web
Any agent
npx skills add fmind/dot --skill modern-web
Clone the repo
git clone --depth 1 https://github.com/fmind/dot

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for modern-web

README.md
[![agentmods](https://agentmods.dev/badge/skills/fmind/dot/modern-web.svg)](https://agentmods.dev/skills/fmind/dot/modern-web)
Your own site
<a href="https://agentmods.dev/skills/fmind/dot/modern-web"><img src="https://agentmods.dev/badge/skills/fmind/dot/modern-web.svg" alt="Measured on agentmods" height="20"></a>
Per session 36 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 722 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00036 $0.00722
Opus 5 $0.00018 $0.00361
Sonnet 5 $0.00007 $0.00144
Haiku 4.5 $0.00004 $0.00072

Measured yesterday against content hash d8734d12c4a4, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

modern-web 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 yesterday.

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.

skills/modern-web/SKILL.md · 52 lines

How it starts

The opening of the file, as written. The whole thing — 52 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Modern Web Guidance

Modern Web Guidance embeds web platform expertise, browser compatibility data, and modern baseline practices directly into coding agents. It steers code generation away from obsolete polyfills and heavy JavaScript abstractions toward native HTML, modern CSS, and standard browser APIs. Front-end frameworks route through angular or typescript-stack; browser automation and testing route through playwright and chrome-devtools.

1. Retrieve Guidance

  1. Search guidelines: Query curated web platform recipes and modern practices using the CLI:
    npx modern-web-guidance@latest search "<topic or api>"
    
  2. Fetch specific pattern: Retrieve detailed implementation guidelines and browser baselines by guide identifier:
    npx modern-web-guidance@latest retrieve "<guide-id>"
    

2. Adoption Workflow

  1. Prefer web platform primitives: Prioritize native elements (<dialog>, <details>, popover API, subgrid, container queries, CSS nesting) over third-party component libraries or custom script wrappers.
  2. Verify baseline compatibility: Check baseline availability and browser support before adopting newly standardized APIs; fall back progressively without blocking core experiences.
  3. Audit with DevTools: Validate rendering, performance, and accessibility against live browser sessions using chrome-devtools and quality-assurance.

Gotchas

  • Preview status: Modern Web Guidance is an evolving catalog; always verify API signatures and baseline status against authoritative MDN documentation.
  • Framework integration: When working within frameworks like Angular, align native web APIs with framework lifecycle and reactivity models per angular.
  • Progressive enhancement: Native dialogs, popovers, and top-layer elements require careful focus and accessibility management; verify keyboard navigation.

Read the full file on GitHub · 52 lines

Changes

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.

  1. yesterday First seen · 52 lines · 36 tokens per session scan A d8734d12c4a4

Subscribe to this mod's changes

modern-web is a skill published in the GitHub repository fmind/dot (4 stars, last pushed today), licensed MIT. It adds 36 tokens to every session and 722 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-04.