# GTK3 and GTK4

Generated from the palette, installed as `~/.themes/udt`. One fixed name for
every scheme, like Kvantum: the name is referenced by gsettings and by the
GTK4 symlink, so a per-scheme name would mean rewriting both on every switch
and leaving stale themes behind.

Derived from `catppuccin/gtk` v1.0.3, which is **archived upstream**. Forking
it is deliberate: it is the theme this desktop already ran, and it will not
track future GTK4/libadwaita changes. Replacing it means replacing these
templates, not editing a consumer.

## What is substituted

Colours appear in two forms and both are replaced: the hex (`#b7bdf8`) and the
bare decimal triple GTK writes inside `rgba()` (`183, 189, 248`). Substitution
is whole-file, not confined to the `@define-color` block at the tail, because
the 8400 lines above it hardcode palette colours too. That was measured, not
assumed: 338 occurrences in GTK3 and 328 in GTK4 sit outside the block.

`#eff1f5` is upstream's foreground, which is Latte `text`, a near-white it
pairs with a Macchiato background. It maps to the `fg` role so GTK text matches
rofi, kitty and waybar rather than being brighter than all of them.

The generator replaces `@ROLE_RGB@` before `@ROLE@`, because `@FG@` is a prefix
of `@FG_RGB@` and the other order would eat the start of the triple placeholder
and leave a literal `_RGB@` in the CSS.

## What is left alone

Neutral greys and upstream's derived tints: `#3e4152`, `#2e3143`, the
`rgba(0, 0, 0, ...)` shadows, `#ffffff`, and the `*_500`/`*_700`/`*_900`
Material swatch constants, which ship with every build and are not theme
colour. Same rule as the Kvantum SVG: shading is not palette.

Two derived values are mapped anyway, because they are semantic rather than
shading: `17, 17, 27` (Latte crust, used as text on the accent) becomes
`bg_deep`, and `182, 106, 119` (a darkened red on the close button) becomes
`critical`.

## Assets

67 SVGs, carrying only three palette colours: `bg`, `bg_alt` and the accent,
the last in 36 of them. The upstream `gtk-3.0/assets` and `gtk-4.0/assets`
directories are byte-identical, so one templated set is rendered and copied
into both.

They are discovered from disk by the generator rather than listed, because
they arrive as a set from upstream and a hand-written list would silently miss
one added by a future refresh.

## Gotchas

- **GTK3 takes its theme name from gsettings on Wayland**, not `settings.ini`.
  The file is written too, but gsettings wins; it was once pinned to `Breeze`,
  silently overriding the file for who knows how long.
- **GTK4 ignores `gtk-theme-name` entirely.** Its stylesheet is imported by
  `~/.config/gtk-4.0/gtk.css` through the `theme` symlink.
- **`gtk-dark.css` must exist** alongside `gtk.css`. Apps request one or the
  other depending on the prefer-dark setting; upstream ships them identical.
- **GTK apps only reread a theme at startup**, like Qt. A running app keeps the
  old colours, which is why the accent here is the fixed fallback rather than
  the wallpaper-tracking one.
- **A placeholder with no matching role renders literally** and GTK drops the
  declaration with no error. `udt-palette --selftest` asserts every placeholder
  in these templates maps to a role, because 8500 lines is too much to eyeball.