The document discusses the CSS Nesting Spec which allows CSS selectors to be nested without duplicate selectors, improving browser performance. It notes the CSS spec process from idea to recommendation and how the nesting spec is currently at the Working Draft stage. It also provides examples of how to experiment with nested rulesets today using PostCSS and links to further resources on the spec and nested CSS.

1. SingaporeCSS / Talk.CSS #49 / 1 April 2020
Using the CSS Nesting Spec
Today

2. CSS SPEC PROCESS
FROM CRAZY IDEA TO YOUR BROWSER
Crazy idea Editor’s Draft Working Draft Candidate
Recommendation
CSS Nesting Spec
March 2019

3. NESTED RULESETS
NO MORE DUPLICATE SELECTORS

4. NESTED RULESETS
NO MORE DUPLICATE SELECTORS

5. WHY @NEST IS NEEDED
BROWSER PERFORMANCE AND LOOK-AHEAD PARSING

6. WHEN @NEST ISN’T NEEDED
WHEN & COMES FIRST

7. EXPERIMENTAL CSS, TODAY
postcss-preset-env
https://cssdb.org

8. POSTCSS.CONFIG.JS
AMAZEE'S CONFIGURATION (WORK IN PROGRESS)

9. https://codepen.io/johnalbin/pen/jJJWmo