Groundwork
step 1 of 2

How much CSS do you already have?

Be honest — nobody is watching. This only decides which chapters come first; every chapter stays open to you either way.

Not sure? Start at Beginner — every path opens at the section people usually skip.

Full syllabus

Everything each level eventually covers — ticked sections are written, the rest are still on the desk.

Beginner0 / 8 sections written

Checkpoint: you can lay out a real page with flexbox, responsive to screen size, without fighting the cascade.

Intermediate0 / 9 sections written

Checkpoint: you can build a responsive, themeable app layout with Grid and custom properties, and explain why an element is stacking where it is.

Advanced0 / 8 sections written

Checkpoint: you can diagnose a layout-thrash performance bug, explain a stacking-context surprise, and design a themeable design-token system.

Three honest notes
  • Flexbox comes before Grid on purpose — most real layouts are one-dimensional, and Grid clicks faster once flex's mental model is automatic.
  • Cascade layers and :has() are 2023+ CSS that quietly replace a lot of specificity hacks and JS-driven class toggling — they sit at the top of advanced because everything else assumes the old cascade rules first.
  • Houdini and paint worklets are the deepest, rarest layer — most working CSS developers never touch them, but the advanced tier doesn't skip them.