QuackyardCSS Selectors
Write one CSS selector that picks exactly the elements a level highlights, in as few characters as you can.
Level 1 of 12
Tag names
A selector can be nothing but a tag name, and then it picks every element with that tag — wherever it sits on the page, however deeply it is nested.
The page to pick picked wrong
main#page
h1#page-title
p#intro
p#body-copy
div#footer
p#small-print
Write a selector and watch the page: the boxes it picks light up as you type.
More in the yard
- Base64 Encoder & DecoderEncode text to Base64 and decode it back, in the standard or URL-safe alphabet, without your text leaving the page.
- Bit FlipFlip bits until the board makes the target number: twelve levels from place values to hex, masks and shifts.
- Case ConverterConvert text between camelCase, PascalCase, snake_case, kebab-case, Title Case and more, and make a URL slug.
- chmod CalculatorConvert Unix permissions between octal and symbolic notation, special bits included.
- CIDR & Subnet CalculatorWork out what an IPv4 or IPv6 block covers, split it into subnets, and check whether an address is inside it.
- Code TypingA typing test with real code instead of prose: ten snippets in ten languages, brackets, quotes and all.
- Color Converter & Contrast CheckerConvert a colour between HEX, RGB, HSL and OKLCH, and check two colours against WCAG.
- Cron BuilderRead and write cron expressions in plain English, with the next run times in any timezone.
- CSV ↔ JSON ConverterConvert between CSV and JSON: RFC 4180 quoting, an auto-detected delimiter, typed values, and a preview of the table.
- Date CalculatorCount the days between two dates, and add or subtract days, weeks, months and years.
- Hash GeneratorHash text with MD5, SHA-1, SHA-256, SHA-384 and SHA-512 at once, and check a hash against it.
- JSON Formatter & ValidatorFormat, minify and check JSON, and see the exact line and column where it breaks.
- JSON ↔ YAML ConverterConvert between JSON and YAML: anchors resolved, multi-document files handled, and output that round-trips.
- JWT DecoderDecode a JSON Web Token in your browser and read its header, claims and expiry in plain words.
- Number Base ConverterConvert a number between binary, octal, decimal, hex and any base from 2 to 36, however big it is.
- Password GeneratorMake strong passwords and passphrases from your browser’s own randomness, and check how strong a password is.
- QR Code GeneratorMake a QR code for a link, Wi-Fi, an email or a phone number, and download it as SVG or PNG.
- Regex TrainerLearn regular expressions one level at a time: match one list, skip the other, in as few characters as you can.
- Shell PipesBuild Unix pipelines that turn a log, a CSV or a word list into the target output, in as few characters as you can.
- SQL DetectiveSolve a yard mystery with SQL: ten levels of queries against a small database, in as few characters as you can.
- SQL FormatterFormat SQL for reading, or minify it, in the dialect you use.
- Diff CheckerCompare two texts line by line, word by word or character by character, and copy the unified diff.
- Time Zone ConverterConvert a date and time between time zones, and see it in several at once.
- Unix Timestamp ConverterTurn Unix timestamps into dates and back, in any timezone.
- URL Encoder & DecoderPercent-encode text for URLs, decode it back, and take a URL apart into its pieces.
- UUID Generator & DecoderGenerate version 4 and 7 UUIDs, or take any UUID apart: its version, its variant, and when a time-based one was made.
- Word CounterCount words, characters, sentences and paragraphs as you type, with reading and speaking time.