# mdo/wtf-html-css

Common reasons your HTML and CSS may be fucked.

Repository: https://github.com/mdo/wtf-html-css
Canonical: https://ross.abutalabs.com/products/wtf-html-css
Homepage: http://wtfhtmlcss.com
Language: CSS
License: MIT
License Family: permissive
Last push: 2022-03-04T00:45:49+00:00

## Health v2 (maintenance only)
Score: 23/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 0, release rhythm 8, longevity 100
- inputs: {"age_days": 4546, "days_push": 1644, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1440, forks 80 (observed 2026-08-28T04:04:44.256053+00:00)

## What it is
A curated guide by Bootstrap creator Mark Otto listing common, frustrating HTML and CSS pitfalls and how to avoid them. It is a static documentation site covering gotchas like box model math, float behavior, and browser quirks.

## Use cases
- learn common HTML and CSS pitfalls
- debug why my CSS layout breaks
- understand float and margin collapse behavior
- avoid browser quirks like Mobile Safari rem bugs
- onboard junior frontend developers to CSS gotchas

## When to choose
- you want a quick reference of classic HTML/CSS gotchas
- you're teaching or learning frontend fundamentals
- you're debugging confusing layout or browser-specific issues

## When to avoid
- you need up-to-date coverage of modern CSS (flexbox, grid, container queries)
- you want an interactive tool or linter rather than a reading list
- you need comprehensive documentation rather than a curated list of quirks

## Facets
- artifact type: learning-resource
- maturity: maintenance
- function: documentation, ui-components
- domain: web-development, frontend, tutorials
- platform: browser
- tags: css, html, gotchas, frontend-tips, curated-list, web-server

## Member repositories
- mdo/wtf-html-css (main) score 23

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:04:44.256053+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T04:36:32.201618+00:00, confidence not recorded.
  - readme: https://github.com/mdo/wtf-html-css (fetched 2026-08-28T04:04:44.256053+00:00, sha 71bd4356b813)
  - homepage: http://wtfhtmlcss.com (fetched 2026-08-29T11:46:48.384805+00:00, sha 419af91a60a2)
- Data as of 2026-08-30T08:39:29.467469+00:00.