This blew my mind today:

• 12 Little-Known CSS Facts Show archive.org snapshot
• 12 Little-Known CSS Facts (The Sequel) Show archive.org snapshot

Rails Long Term Support

Rails LTS provides security patches for old versions of Ruby on Rails (2.3, 3.2, 4.2 and 5.2)

• Prevents you from data breaches and liability risks
• Upgrade at your own pace
• Works with modern Rubies

Read more Show archive.org snapshot

Please make sure to check browser support for CSS features on Can I Use Show archive.org snapshot and the Mozilla Development Network Show archive.org snapshot before using.

Favorites

• outline-offset: specify how far away from the element an outline is rendered
• ::first-letter: matches the first letter inside an element
• Using Unicode letters as css classes, e.g. ★
• font-weight: relative keywords bolder and lighter, which will render a font in "inherited font-weight +/- 100"