Migrating to 0.20

Coming from another framework, most of the work is unlearning rather than learning. The tables below map what you already know onto what exists here, and name the places where there is deliberately no equivalent.

From Bootstrap

No equivalent, on purpose: a carousel, a JavaScript grid system, utility classes for every property, and jQuery-era data attributes for behaviour the platform now does itself.

From Tailwind

The mental shift is larger. Tailwind composes a component out of dozens of atoms in the markup; here a component is one class and the atoms exist only for the gaps between components.

What you gain: no compiler, no purge step, markup you can read aloud, and a theme that changes at runtime. What you give up: the enormous atomic vocabulary. If you want a utility for every property, keep Tailwind — that is a real preference, not a mistake.

From Pico or another classless framework

Load PolyFishCSS-Classless.css and your existing semantic HTML gets styled with no classes at all. It sits in the lowest layer, so the moment you add a pf- class, that class wins. That makes the migration incremental: start classless, add components where you need more than the defaults.

A migration that does not stall

1. Load PolyFish after your current framework

   Both will fight for a while. Keep your old stylesheet last so nothing breaks visually on day one.

2. Move the tokens first

   Map your brand colours onto --pf-accent, --pf-bg and --pf-text. The whole framework follows immediately.

3. Convert page furniture next

   Header, footer, containers and sections. These are the least risky and the most visible.

4. Then components, page by page

   Cards, tables, forms. Delete the old classes as you go rather than leaving both.

5. Drop the old stylesheet and measure

   Check contrast and check the page at 320px. Both are where migrations leave debris.

Renamed since you last looked

Pre-1.0, a minor release may rename or remove things. Every change is listed here with its replacement, and the class reference always lists the current name. Renames from 0.16 and 0.17 are in the token table.

Renamed in 0.20

Six classes renamed to the rule the rest of the framework follows, before the API freezes for 1.0.

Removed in 0.20

The aliases file is gone, so these need an edit rather than a compatibility link. Every removal has a one-for-one replacement except where the note says otherwise.