kview.css looked-up colours unresolved in fragment-attached scenes — String to Paint CSS warnings on JavaFX 27-ea

[knowledge-graphlet]

Symptom

Repeated WARN-level CSS failures on JavaFX 27-ea:

j.css - Caught java.lang.ClassCastException: class java.lang.String cannot be cast to class javafx.scene.paint.Paint
  while converting value for -fx-background-color from rule *.reasoner-result-header *.label in stylesheet .../kview.css
j.css - ... from rule *.search-sort-button in stylesheet .../kview.css

Analysis

Both rules use looked-up colours defined only in kview.css's .root block:

.search-sort-button       { -fx-background-color: -Secondary-05; ... }
.reasoner-result-header .label { -fx-background-color: -Grey-9; ... }
.root { -Grey-1: #FBFBFC; ... }   /* all palette variables */

kview.css is frequently attached to FXML fragments (stylesheets="@../kview.css" on a sub-pane). A stylesheet attached at a sub-pane applies only to that pane and below, so its .root rule never matches the scene root there. In any scene where kview.css arrives only via a fragment — the reasoner result surface, the navigator search area — the palette variables are undefined at the point of use. JavaFX 27-ea's converter reports the unresolved lookup as the String→Paint ClassCastException above (earlier releases logged a quieter could-not-resolve warning).

This is not only log noise: the affected -fx-background-color (and any other looked-up value in that scene) silently fails to apply, so those controls render unstyled in exactly the fragment-attached contexts.

Not introduced by current branch work — kview.css has no changes against main; the trigger is the 27-ea pin (see the JavaFX 27-ea+24 pin rationale in komet-bom) making a long-standing scoping gap loud.

Fix directions

• Ensure the palette variables reach every scene that uses kview.css fragments: either attach kview.css (or a dedicated palette stylesheet containing only the variable block) at the scene/application level for every window and popup, or
• move the variable block from .root to * scope in kview.css (broader matching, with the usual specificity cautions), or
• stop attaching kview.css per-fragment and rely on application-level attachment alone.

Acceptance

• No String cannot be cast to ... Paint warnings from kview.css rules at startup or when opening the reasoner results and navigator search surfaces.
• .search-sort-button and .reasoner-result-header .label render their palette backgrounds in every window they appear in.