fix(portal-shell): dark mode actually applies to component-scoped surfaces (#87)

## Bug Three component stylesheets (`app.scss`, `sidebar.scss`, `theme-switcher.scss`) carried `:where(.dark) &` rules to react to the `<html>.dark` class — the same pattern Tailwind uses internally. **Angular's emulated CSS encapsulation descends into `:where()` and rewrites its contents with the `_ngcontent-XXX` scoping attribute**, so the produced selector looked like: ```css :where(.dark[_ngcontent-c0]) .shell-main[_ngcontent-c0] { ... } ``` `<html>` carries `.dark` but no `_ngcontent` attribute — the rule never matched. Visible symptom: the main page background stayed light even when `.dark` was on `<html>` and every Tailwind `dark:` utility in the templates was working correctly. Sidebar hover/focus/active states and the theme-switcher menu surface had the same bug. ## Fix - **`app.scss` and `sidebar.scss`** switch to `:host-context(.dark)`. The Angular compiler recognises this directive and expands it without forcing the ancestor (`<html>`) to carry the scoping attribute. Compiled output: ```css .dark[_nghost-c0] .shell-main[_ngcontent-c0], .dark [_nghost-c0] .shell-main[_ngcontent-c0] { ... } ``` The second selector matches `<html>.dark` as an ancestor of `<app-root>` (the host) — exactly what we want. - **`theme-switcher` switches to `ViewEncapsulation.None`**. Its CDK menu opens in an overlay portal appended to `<body>` — outside the component's host subtree — so even `:host-context()` would miss it. With encapsulation disabled, the styles emit globally; the BEM-style class names (`.theme-switcher__menu`, `.theme-switcher__item`, ...) keep the rules contained without leaking. ## Drive-by - Remove the right border on the `.header__logo-zone`. The visible hairline above the sidebar was extra noise — the alignment of widths already carries the visual relationship to the rail below. ## Why not also rip out the `dark:` Tailwind utilities used in the templates? They work. They're emitted into the global Tailwind sheet, sit outside view encapsulation, and already handle the `.dark` ancestor lookup via their own selector (`:where(.dark, .dark *)`). The bug was specifically about component-authored CSS *inside* an SCSS file under emulated encapsulation. ## Test plan - [x] `pnpm exec nx run-many -t lint test build --projects=portal-shell` — green (33 / 33 specs). - [x] Inspect the produced CSS: `:host-context(.dark)` expands to both `.dark[_nghost-XXX]` and `.dark [_nghost-XXX]` selectors, no `_ngcontent` attribute leaked into the `.dark` portion. - [ ] Manual: pick dark mode → `/` shows the dark page background; sidebar hover / active / focus visibly switches; theme-switcher menu opens with the dark surface. - [ ] Manual: header no longer shows a vertical hairline between the logo zone and the search/actions cluster. --------- Co-authored-by: Julien Gautier <julien.gautier@apf.asso.fr> Reviewed-on: #87
2026-05-11 10:45:39 +02:00
parent 0ae7e0e23d
commit 3a0a9c700d
4 changed files with 64 additions and 32 deletions
@@ -3,6 +3,14 @@
 // owns its own scrolling (long menus don't push the header off-screen);
 // the main pane scrolls independently so opening a long page never
 // scrolls the sidebar out of view.
 //
 // Dark mode goes through `:host-context(.dark)` — the `.dark` class
 // sits on <html>, outside this component's view encapsulation, so a
 // nested `:where(.dark) &` would compile to a selector with the
 // `_ngcontent` attribute appended to `.dark` itself, which <html>
 // doesn't carry. `:host-context()` is the Angular-canonical escape
 // hatch that walks the DOM up from the host and matches without
 // applying the scoping attribute to the ancestor selector.
 :host {
  display: flex;
  flex-direction: column;
@@ -22,11 +30,11 @@
  overflow-y: auto;
  background-color: #f9fafb;
  color: #111827;
 }
-  :where(.dark) & {
+:host-context(.dark) .shell-main {
  background-color: #0b1220;
  color: #e5e7eb;
  }
 }
 // Skip-link (WCAG 2.4.1 "Bypass Blocks"). Hidden by default, fully
@@ -5,6 +5,10 @@
 // change, update both files together — extracting a shared SCSS
 // variable would be the right move only if a third surface needs the
 // same coupling.
 //
 // No vertical divider between the logo zone and the rest of the
 // header on purpose — the alignment carries the visual relationship
 // to the sidebar rail below; a second hairline would only add noise.
 .header__logo-zone {
  display: flex;
  align-items: center;
@@ -12,13 +16,8 @@
  width: 16rem;
  height: 100%;
  padding: 0 0.75rem;
  border-right: 1px solid #e5e7eb;
  transition: width 0.18s ease-out;
  :where(.dark) & {
    border-right-color: #1f2937;
  }
  &--collapsed {
    width: 4rem;
    padding: 0 0.5rem;
@@ -4,6 +4,12 @@
 // room on each side. The transition is short and animation-friendly —
 // users with `prefers-reduced-motion: reduce` get the no-animation
 // branch below.
 //
 // Dark mode rules sit OUTSIDE the nested blocks and key off
 // `:host-context(.dark)` — `.dark` lives on <html>, outside this
 // component's encapsulation, and a nested `:where(.dark) &` would be
 // rewritten by Angular's emulated CSS scoping into a selector that
 // no longer matches <html>.
 .sidebar {
  width: 16rem;
  transition: width 0.18s ease-out;
@@ -44,27 +50,14 @@
    background-color 0.12s ease-out,
    color 0.12s ease-out;
  :where(.dark) & {
    color: #e5e7eb;
  }
  &:hover {
    background-color: #f3f4f6;
    color: var(--color-brand-primary-500);
    :where(.dark) & {
      background-color: #1f2937;
      color: var(--color-brand-primary-300);
    }
  }
  &:focus-visible {
    outline: 2px solid var(--color-brand-primary-500);
    outline-offset: 2px;
    :where(.dark) & {
      outline-color: var(--color-brand-primary-300);
    }
  }
 }
@@ -76,15 +69,6 @@
    background-color: var(--color-brand-primary-600);
    color: #fff;
  }
  :where(.dark) & {
    background-color: var(--color-brand-primary-400);
    &:hover {
      background-color: var(--color-brand-primary-300);
      color: #0b1620;
    }
  }
 }
 .sidebar__label {
@@ -101,3 +85,30 @@
    padding-right: 0.5rem;
  }
 }
 // --- Dark mode overrides --------------------------------------------------
 :host-context(.dark) {
  .sidebar__link,
  .sidebar__toggle {
    color: #e5e7eb;
    &:hover {
      background-color: #1f2937;
      color: var(--color-brand-primary-300);
    }
    &:focus-visible {
      outline-color: var(--color-brand-primary-300);
    }
  }
  .sidebar__link--active {
    background-color: var(--color-brand-primary-400);
    &:hover {
      background-color: var(--color-brand-primary-300);
      color: #0b1620;
    }
  }
 }
@@ -1,5 +1,11 @@
 import { CdkMenu, CdkMenuItem, CdkMenuTrigger } from '@angular/cdk/menu';
-import { ChangeDetectionStrategy, Component, computed, inject } from '@angular/core';
+import {
  ChangeDetectionStrategy,
  Component,
  ViewEncapsulation,
  computed,
  inject,
 } from '@angular/core';
 import { Icon, type IconName } from '../icon/icon';
 import { LayoutStateService, type ThemeMode } from '../../state/layout-state.service';
@@ -36,6 +42,14 @@ const MODE_OPTIONS: readonly ModeOption[] = [
  templateUrl: './theme-switcher.html',
  styleUrl: './theme-switcher.scss',
  changeDetection: ChangeDetectionStrategy.OnPush,
  // The CDK menu opens in an overlay portal appended to <body>, so it
  // is NOT a descendant of this component's host. With the default
  // emulated encapsulation, the menu DOM would lose the scoping
  // attribute and our `.theme-switcher__*` rules would not apply.
  // Disabling encapsulation emits the styles into the global sheet —
  // the BEM-style class names below are specific enough to avoid
  // collisions, and `.dark` ancestor matching just works.
  encapsulation: ViewEncapsulation.None,
 })
 export class ThemeSwitcher {
  private readonly layout = inject(LayoutStateService);