rfellows commented on code in PR #11322:
URL: https://github.com/apache/nifi/pull/11322#discussion_r3390464973
##########
nifi-frontend/src/main/frontend/apps/nifi/src/app/app.component.scss:
##########
@@ -16,6 +16,8 @@
*/
.splash {
+ background-color: var(--mat-sys-secondary);
Review Comment:
This rule used to be registered globally via `@include
app-component.generate-theme()` in `styles.scss`, so it matched `.splash`
everywhere — including the loading-state `<div class="splash">` in
`pages/login/feature/login.component.html`. Now that it's scoped to
`AppComponent` via view-encapsulation, the login page's `.splash` no longer
picks up `var(--mat-sys-secondary)` as its background.
Fix options:
1. Duplicate the rule into `login.component.scss`.
2. Since the markup is essentially identical in both places, promote
`.splash` / `.splash-img` to a small global partial (e.g.
`themes/components/_splash.scss`) registered from `material.scss`.
3. Extract a tiny shared `<splash-screen>` component reused by both pages.
The loading-state splash on `/login` is the surface to re-verify visually
after whichever fix you choose.
##########
nifi-frontend/src/main/frontend/libs/shared/src/assets/themes/README.md:
##########
@@ -0,0 +1,353 @@
+<!--
+ Licensed to the Apache Software Foundation (ASF) under one or more
+ contributor license agreements. See the NOTICE file distributed with
+ this work for additional information regarding copyright ownership.
+ The ASF licenses this file to You under the Apache License, Version 2.0
+ (the "License"); you may not use this file except in compliance with
+ the License. You may obtain a copy of the License at
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+-->
+
+# Theme Architecture
+
+This directory contains the Angular Material theming layer for the NiFi
frontend.
+
+---
+
+## Contents
+
+- [Design System Overview](#design-system-overview)
+- [Theme Stack](#theme-stack)
+- [How `.darkMode` Works](#how-darkmode-works)
+- [Decision Tree: Does This Need a `.darkMode`
Block?](#decision-tree-does-this-need-a-darkmode-block)
+- [Component Style Ownership](#component-style-ownership)
+- [Styling Dynamically Created Elements
(`::ng-deep`)](#styling-dynamically-created-elements-ng-deep)
+- [File Structure](#file-structure)
+
+---
+
+## Design System Overview
+
+The NiFi UI uses [Angular Material](https://material.angular.io/) which
implements Google's
+[Material Design 3](https://m3.material.io/) specification. The theme applies
a minimally
+customized MD3 appearance — functional and accessible, without a proprietary
design token layer.
+
+Snowflake's fork (`openflow-ui`) sits on top of this same Angular Material
base but replaces the
+palette values with Snowflake's Stellar design system tokens (Balto). Code
flows in both directions
+between the repositories, so it is important to understand where the two
implementations differ.
+
+---
+
+## Theme Stack
+
+```
+md-ref-palette-* values (defined once in material.scss for light; swapped in
.darkMode for dark)
+ ↓
+mat.theme() + mat.theme-overrides() → --mat-sys-* system tokens
+ ↓
+per-component partials: mat.*-overrides() + plain CSS using --mat-sys-*, --nf-*
+ ↓
+Rendered UI
+```
+
+### Entry point: `material.scss`
+
+`material.scss` is the orchestrator. It:
+
+1. Defines the MD3 palette via `--md-ref-palette-*` values.
+2. Calls `mat.theme()` once to generate all `--mat-sys-*` system tokens.
+3. Calls `generate-material-theme()` from each component partial to apply
per-component overrides.
+
+`material.scss` is loaded via `@use` in each app's `styles.scss`. Its dark
theme is
+self-contained — the `.darkMode {}` blocks live inside `material.scss` and
inside the component
+partials that need palette-index swaps. No app-level `styles.scss` needs to
call any material
+mixin a second time for dark mode.
+
+### Token sources
+
+| Token | Example | Mode-aware?
|
+| --------------- | ------------------------------------- |
---------------------------------------------------------- |
+| Material system | `--mat-sys-primary` | Yes —
`mat.theme()` resolves differently under `.darkMode` |
+| NiFi-specific | `--nf-success-default` | Yes — rebound
under `.darkMode` in `material.scss` |
+| Raw palette | `--md-ref-palette-neutral-variant-60` | No — fixed index;
must swap manually in `.darkMode` |
+
+---
+
+## How `.darkMode` Works
+
+### Why most `mat.*-overrides()` do NOT need `.darkMode` in NiFi
+
+Angular Material's `mat.theme-overrides()` sets component tokens (`--mdc-*`,
`--mat-*`) on `<body>`
+in dark mode. Our `mat.*-overrides()` set them on `<html>` (`:root`). Since
`<body>` is a child of
+`<html>`, the `<body>` value wins the cascade.
+
+In **openflow-ui**, this matters because our per-component colors come from
`--themed-*` tokens
+which auto-rebind under `.darkMode`. When those tokens are used inside
`mat.*-overrides()`, the
+`<body>` Material dark-theme value overrides our `:root` value unless we
re-declare in `.darkMode`.
+
+In **NiFi**, most `mat.*-overrides()` use `--mat-sys-*` tokens (e.g.,
`--mat-sys-secondary-container`).
+These tokens are themselves already set correctly for dark mode by
`mat.theme()`. Angular Material's
+dark-theme defaults for those same component tokens typically equal the
light-mode values when those
+tokens use `--mat-sys-*` references, so no explicit `.darkMode` is needed.
+
+### When NiFi DOES need `.darkMode`
+
+A `.darkMode` block is needed when a `mat.*-overrides()` call hard-codes a
**raw palette index**
+(`--md-ref-palette-neutral-variant-N`) that must resolve to a **different
index** in dark mode.
+
+**Example** (`_snackbar.scss`):
+
+```scss
+:root {
+ @include mat.snack-bar-overrides(
+ (
+ button-color: var(--md-ref-palette-secondary-80),
+ // light: pale blue-grey
+ )
+ );
+}
+
+// The snackbar action button uses a fixed hex in dark mode (#004849, a dark
teal)
+// rather than a palette variable. This is the only way to express this design
intent.
+.darkMode {
+ @include mat.snack-bar-overrides(
+ (
+ button-color: #004849
+ )
+ );
+}
+```
+
+**Example with palette index swap** (`_checkbox.scss`):
+
+```scss
+:root {
+ .tertiary-checkbox {
+ @include mat.checkbox-overrides(
+ (
+ selected-icon-color: var(--md-ref-palette-tertiary-40),
+ // light: medium brown
+ )
+ );
+ }
+}
+
+// Tertiary palette index 40 is too dark in dark mode; index 70 (lighter) is
correct.
+.darkMode {
+ .tertiary-checkbox {
+ @include mat.checkbox-overrides(
+ (
+ selected-icon-color: var(--md-ref-palette-tertiary-70)
+ )
+ );
+ }
+}
+```
+
+Partials that follow this pattern: `_button.scss`, `_checkbox.scss`,
+`_progress-spinner.scss`, `_snackbar.scss`.
+
+### The DOM inheritance problem (context for code reviewers)
+
+If you see a `.darkMode` block in a NiFi partial that mirrors its `:root`
block byte-for-byte,
+where every value uses `--mat-sys-*` or `--nf-*` tokens, that block is
redundant and should be
+removed. The `--mat-sys-*` and `--nf-*` variables are already rebound for dark
mode at the
+`material.scss` level, making the duplication emit the same CSS twice without
changing any
+computed values.
+
+The canonical rule: **only raw palette index swaps belong in NiFi `.darkMode`
blocks**.
+
+---
+
+## Decision Tree: Does This Need a `.darkMode` Block?
+
+```
+Is this property non-color?
+(size, height, width, weight, tracking, line-height, shape,
+ padding, spacing, opacity, transform, etc.)
+ │
+ ├─ YES → Do NOT put it in .darkMode. Same in both modes.
+ │
+ └─ NO (color-related) → Continue ↓
+
+Does the value use --mat-sys-* or --nf-* tokens?
+ │
+ ├─ YES → These tokens resolve correctly for the current mode.
+ │ No .darkMode block needed.
+ │
+ └─ NO → Is it a raw palette index --md-ref-palette-*-N ?
+ │
+ ├─ YES → Does dark mode need a DIFFERENT index?
+ │ ├─ YES → Add .darkMode with the alternate index.
+ │ └─ NO → No .darkMode needed.
+ │
+ └─ NO (raw px, rgba, or keyword) → Evaluate case by case.
+ Plain rgba() box-shadow values do not change per mode
+ (e.g., _date-picker.scss). No .darkMode needed.
+```
+
+### Quick reference
+
+| Scenario |
`.darkMode` needed? |
+| ----------------------------------------------------------------------- |
------------------------------ |
+| `mat.*-overrides()` with `--mat-sys-*` tokens |
**No** — tokens are mode-aware |
+| `mat.*-overrides()` with `--nf-*` tokens |
**No** — tokens are mode-aware |
+| `mat.*-overrides()` with raw `--md-ref-palette-*-N` that flips per mode |
**Yes** |
+| `mat.*-overrides()` with size, shape, typography |
**No** — same in both modes |
+| Plain CSS `background-color: var(--mat-sys-surface)` |
**No** — auto-resolves |
+| Byte-for-byte duplicate of `:root` block |
**No** — redundant, delete it |
+
+---
+
+## Component Style Ownership
+
+Each component owns its own styles in its `*.component.scss` file. There are
**no** component-theme
+mixin registrations in any app's `styles.scss`.
+
+### What lives where
+
+| Style type
| Location |
+| ----------------------------------------------------------------------------
| ---------------------------------------------------------------------- |
+| Angular Material palette, system tokens (`--mat-sys-*`), `mat.*-overrides()`
| `themes/components/_*.scss` partials, orchestrated by `material.scss` |
+| App structural resets (html/body, link styles, utility classes)
| Inlined directly in `material.scss` |
+| Table and Prism syntax highlighting styles
| `themes/components/_table.scss`, `themes/components/_prism-theme.scss` |
+| Tailwind v4 `@theme` configuration
| `themes/_tailwind-theme.scss` |
+| Component-specific layout, sizing, and color overrides
| `*.component.scss` (co-located with the component) |
+
+### `styles.scss` is a framework orchestrator only
+
+Each app's `styles.scss` contains exactly these entries and nothing else:
+
+```scss
+@use 'sass:meta';
+@use 'tailwindcss';
+@use 'libs/shared/src/assets/themes/tailwind-theme';
+@use 'libs/shared/src/assets/fonts/flowfont/flowfont.css';
+@use 'libs/shared/src/assets/themes/material';
+
+@layer base {
+ @include meta.load-css('font-awesome');
+}
+
+@source #{"'libs/shared/src'"};
+```
+
+**There is no `html {}` block, no `@include component.generate-theme()`, and no
+`.darkMode` double-call block in any `styles.scss`.** Dark-mode behavior is
handled entirely
+inside `material.scss` and its component partials.
+
+---
+
+## Styling Dynamically Created Elements (`::ng-deep`)
+
+Angular's emulated view encapsulation adds `[_ngcontent-xxx]` attributes to
elements defined in
+a component's template, scoping that component's styles to those elements
only. Elements created
+programmatically (e.g., via D3 or `document.createElement()`) do NOT receive
those attributes, so
+component-scoped styles cannot reach them.
+
+**Pattern:** Use `::ng-deep` in a component's stylesheet to pierce
encapsulation:
+
+```scss
+// birdseye.component.scss
+:host ::ng-deep #birdseye {
+ width: 266px;
+ height: 150px;
+ // structural styles only
+}
+```
+
+**Rules for `::ng-deep` + dark mode:**
+
+| Situation | `.darkMode` block inside
`::ng-deep`? |
+| --------------------------------------------- |
----------------------------------------------- |
+| Structural / layout rules only | **No** — no color involved
|
+| Colors using `--mat-sys-*` or `--nf-*` tokens | **No** — tokens auto-resolve
|
+| Colors using raw `--md-ref-palette-*-N` | **Yes** — add internal
`.darkMode` for the swap |
+
+NiFi's `canvas.component.scss` and `birdseye.component.scss` only contain
structural layout rules
+inside `::ng-deep`. Colors use `--mat-sys-*` and `--nf-*` CSS custom
properties that already
+resolve correctly for both light and dark mode. No `.darkMode` block is needed
inside `::ng-deep`
+for these components.
Review Comment:
Heads up: `apps/nifi/src/app/ui/common/canvas/canvas.component.scss` and
`apps/nifi/src/app/ui/common/birdseye/birdseye.component.scss` (the new shared
replacements introduced by NIFI-15951 and consumed by `connector-canvas`) still
use the old `@mixin styles(); @mixin generate-theme(); :host ::ng-deep {
@include styles(); @include generate-theme(); .darkMode { @include
generate-theme(); } }` pattern — including the redundant double-include for
`.darkMode`. They weren't touched by this PR.
That means the pattern this PR is "removing" actually still ships in the
codebase, just relocated. Ideally these get migrated alongside the legacy
`pages/flow-designer/...` versions you already moved. If you'd rather defer it,
please mention the exception in the PR description and add a note here so the
next maintainer doesn't think the pattern is fully gone.
##########
nifi-frontend/src/main/frontend/libs/shared/src/assets/themes/README.md:
##########
@@ -0,0 +1,353 @@
+<!--
+ Licensed to the Apache Software Foundation (ASF) under one or more
+ contributor license agreements. See the NOTICE file distributed with
+ this work for additional information regarding copyright ownership.
+ The ASF licenses this file to You under the Apache License, Version 2.0
+ (the "License"); you may not use this file except in compliance with
+ the License. You may obtain a copy of the License at
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+-->
+
+# Theme Architecture
+
+This directory contains the Angular Material theming layer for the NiFi
frontend.
+
+---
+
+## Contents
+
+- [Design System Overview](#design-system-overview)
+- [Theme Stack](#theme-stack)
+- [How `.darkMode` Works](#how-darkmode-works)
+- [Decision Tree: Does This Need a `.darkMode`
Block?](#decision-tree-does-this-need-a-darkmode-block)
+- [Component Style Ownership](#component-style-ownership)
+- [Styling Dynamically Created Elements
(`::ng-deep`)](#styling-dynamically-created-elements-ng-deep)
+- [File Structure](#file-structure)
+
+---
+
+## Design System Overview
+
+The NiFi UI uses [Angular Material](https://material.angular.io/) which
implements Google's
+[Material Design 3](https://m3.material.io/) specification. The theme applies
a minimally
+customized MD3 appearance — functional and accessible, without a proprietary
design token layer.
+
+Snowflake's fork (`openflow-ui`) sits on top of this same Angular Material
base but replaces the
+palette values with Snowflake's Stellar design system tokens (Balto). Code
flows in both directions
+between the repositories, so it is important to understand where the two
implementations differ.
+
+---
+
+## Theme Stack
+
+```
+md-ref-palette-* values (defined once in material.scss for light; swapped in
.darkMode for dark)
+ ↓
+mat.theme() + mat.theme-overrides() → --mat-sys-* system tokens
+ ↓
+per-component partials: mat.*-overrides() + plain CSS using --mat-sys-*, --nf-*
+ ↓
+Rendered UI
+```
+
+### Entry point: `material.scss`
+
+`material.scss` is the orchestrator. It:
+
+1. Defines the MD3 palette via `--md-ref-palette-*` values.
+2. Calls `mat.theme()` once to generate all `--mat-sys-*` system tokens.
+3. Calls `generate-material-theme()` from each component partial to apply
per-component overrides.
+
+`material.scss` is loaded via `@use` in each app's `styles.scss`. Its dark
theme is
+self-contained — the `.darkMode {}` blocks live inside `material.scss` and
inside the component
+partials that need palette-index swaps. No app-level `styles.scss` needs to
call any material
+mixin a second time for dark mode.
+
+### Token sources
+
+| Token | Example | Mode-aware?
|
+| --------------- | ------------------------------------- |
---------------------------------------------------------- |
+| Material system | `--mat-sys-primary` | Yes —
`mat.theme()` resolves differently under `.darkMode` |
+| NiFi-specific | `--nf-success-default` | Yes — rebound
under `.darkMode` in `material.scss` |
+| Raw palette | `--md-ref-palette-neutral-variant-60` | No — fixed index;
must swap manually in `.darkMode` |
+
+---
+
+## How `.darkMode` Works
+
+### Why most `mat.*-overrides()` do NOT need `.darkMode` in NiFi
+
+Angular Material's `mat.theme-overrides()` sets component tokens (`--mdc-*`,
`--mat-*`) on `<body>`
+in dark mode. Our `mat.*-overrides()` set them on `<html>` (`:root`). Since
`<body>` is a child of
+`<html>`, the `<body>` value wins the cascade.
+
+In **openflow-ui**, this matters because our per-component colors come from
`--themed-*` tokens
+which auto-rebind under `.darkMode`. When those tokens are used inside
`mat.*-overrides()`, the
+`<body>` Material dark-theme value overrides our `:root` value unless we
re-declare in `.darkMode`.
+
+In **NiFi**, most `mat.*-overrides()` use `--mat-sys-*` tokens (e.g.,
`--mat-sys-secondary-container`).
+These tokens are themselves already set correctly for dark mode by
`mat.theme()`. Angular Material's
+dark-theme defaults for those same component tokens typically equal the
light-mode values when those
+tokens use `--mat-sys-*` references, so no explicit `.darkMode` is needed.
+
+### When NiFi DOES need `.darkMode`
+
+A `.darkMode` block is needed when a `mat.*-overrides()` call hard-codes a
**raw palette index**
+(`--md-ref-palette-neutral-variant-N`) that must resolve to a **different
index** in dark mode.
+
+**Example** (`_snackbar.scss`):
+
+```scss
+:root {
+ @include mat.snack-bar-overrides(
+ (
+ button-color: var(--md-ref-palette-secondary-80),
+ // light: pale blue-grey
+ )
+ );
+}
+
+// The snackbar action button uses a fixed hex in dark mode (#004849, a dark
teal)
+// rather than a palette variable. This is the only way to express this design
intent.
+.darkMode {
+ @include mat.snack-bar-overrides(
+ (
+ button-color: #004849
+ )
+ );
+}
+```
+
+**Example with palette index swap** (`_checkbox.scss`):
+
+```scss
+:root {
+ .tertiary-checkbox {
+ @include mat.checkbox-overrides(
+ (
+ selected-icon-color: var(--md-ref-palette-tertiary-40),
+ // light: medium brown
+ )
+ );
+ }
+}
+
+// Tertiary palette index 40 is too dark in dark mode; index 70 (lighter) is
correct.
+.darkMode {
+ .tertiary-checkbox {
+ @include mat.checkbox-overrides(
+ (
+ selected-icon-color: var(--md-ref-palette-tertiary-70)
+ )
+ );
+ }
+}
+```
+
+Partials that follow this pattern: `_button.scss`, `_checkbox.scss`,
+`_progress-spinner.scss`, `_snackbar.scss`.
+
+### The DOM inheritance problem (context for code reviewers)
+
+If you see a `.darkMode` block in a NiFi partial that mirrors its `:root`
block byte-for-byte,
+where every value uses `--mat-sys-*` or `--nf-*` tokens, that block is
redundant and should be
+removed. The `--mat-sys-*` and `--nf-*` variables are already rebound for dark
mode at the
+`material.scss` level, making the duplication emit the same CSS twice without
changing any
+computed values.
+
+The canonical rule: **only raw palette index swaps belong in NiFi `.darkMode`
blocks**.
+
+---
+
+## Decision Tree: Does This Need a `.darkMode` Block?
+
+```
+Is this property non-color?
+(size, height, width, weight, tracking, line-height, shape,
+ padding, spacing, opacity, transform, etc.)
+ │
+ ├─ YES → Do NOT put it in .darkMode. Same in both modes.
+ │
+ └─ NO (color-related) → Continue ↓
+
+Does the value use --mat-sys-* or --nf-* tokens?
+ │
+ ├─ YES → These tokens resolve correctly for the current mode.
+ │ No .darkMode block needed.
+ │
+ └─ NO → Is it a raw palette index --md-ref-palette-*-N ?
+ │
+ ├─ YES → Does dark mode need a DIFFERENT index?
+ │ ├─ YES → Add .darkMode with the alternate index.
+ │ └─ NO → No .darkMode needed.
+ │
+ └─ NO (raw px, rgba, or keyword) → Evaluate case by case.
+ Plain rgba() box-shadow values do not change per mode
+ (e.g., _date-picker.scss). No .darkMode needed.
+```
+
+### Quick reference
+
+| Scenario |
`.darkMode` needed? |
+| ----------------------------------------------------------------------- |
------------------------------ |
+| `mat.*-overrides()` with `--mat-sys-*` tokens |
**No** — tokens are mode-aware |
+| `mat.*-overrides()` with `--nf-*` tokens |
**No** — tokens are mode-aware |
+| `mat.*-overrides()` with raw `--md-ref-palette-*-N` that flips per mode |
**Yes** |
+| `mat.*-overrides()` with size, shape, typography |
**No** — same in both modes |
+| Plain CSS `background-color: var(--mat-sys-surface)` |
**No** — auto-resolves |
+| Byte-for-byte duplicate of `:root` block |
**No** — redundant, delete it |
+
+---
+
+## Component Style Ownership
+
+Each component owns its own styles in its `*.component.scss` file. There are
**no** component-theme
+mixin registrations in any app's `styles.scss`.
+
+### What lives where
+
+| Style type
| Location |
+| ----------------------------------------------------------------------------
| ---------------------------------------------------------------------- |
+| Angular Material palette, system tokens (`--mat-sys-*`), `mat.*-overrides()`
| `themes/components/_*.scss` partials, orchestrated by `material.scss` |
+| App structural resets (html/body, link styles, utility classes)
| Inlined directly in `material.scss` |
+| Table and Prism syntax highlighting styles
| `themes/components/_table.scss`, `themes/components/_prism-theme.scss` |
+| Tailwind v4 `@theme` configuration
| `themes/_tailwind-theme.scss` |
Review Comment:
Path drift: `_tailwind-theme.scss` actually lives at
`themes/components/_tailwind-theme.scss`, not `themes/_tailwind-theme.scss`.
##########
nifi-frontend/src/main/frontend/libs/shared/src/assets/themes/README.md:
##########
@@ -0,0 +1,353 @@
+<!--
+ Licensed to the Apache Software Foundation (ASF) under one or more
+ contributor license agreements. See the NOTICE file distributed with
+ this work for additional information regarding copyright ownership.
+ The ASF licenses this file to You under the Apache License, Version 2.0
+ (the "License"); you may not use this file except in compliance with
+ the License. You may obtain a copy of the License at
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+-->
+
+# Theme Architecture
+
+This directory contains the Angular Material theming layer for the NiFi
frontend.
+
+---
+
+## Contents
+
+- [Design System Overview](#design-system-overview)
+- [Theme Stack](#theme-stack)
+- [How `.darkMode` Works](#how-darkmode-works)
+- [Decision Tree: Does This Need a `.darkMode`
Block?](#decision-tree-does-this-need-a-darkmode-block)
+- [Component Style Ownership](#component-style-ownership)
+- [Styling Dynamically Created Elements
(`::ng-deep`)](#styling-dynamically-created-elements-ng-deep)
+- [File Structure](#file-structure)
+
+---
+
+## Design System Overview
+
+The NiFi UI uses [Angular Material](https://material.angular.io/) which
implements Google's
+[Material Design 3](https://m3.material.io/) specification. The theme applies
a minimally
+customized MD3 appearance — functional and accessible, without a proprietary
design token layer.
+
+Snowflake's fork (`openflow-ui`) sits on top of this same Angular Material
base but replaces the
+palette values with Snowflake's Stellar design system tokens (Balto). Code
flows in both directions
+between the repositories, so it is important to understand where the two
implementations differ.
+
+---
+
+## Theme Stack
+
+```
+md-ref-palette-* values (defined once in material.scss for light; swapped in
.darkMode for dark)
+ ↓
+mat.theme() + mat.theme-overrides() → --mat-sys-* system tokens
+ ↓
+per-component partials: mat.*-overrides() + plain CSS using --mat-sys-*, --nf-*
+ ↓
+Rendered UI
+```
+
+### Entry point: `material.scss`
+
+`material.scss` is the orchestrator. It:
+
+1. Defines the MD3 palette via `--md-ref-palette-*` values.
+2. Calls `mat.theme()` once to generate all `--mat-sys-*` system tokens.
+3. Calls `generate-material-theme()` from each component partial to apply
per-component overrides.
+
+`material.scss` is loaded via `@use` in each app's `styles.scss`. Its dark
theme is
+self-contained — the `.darkMode {}` blocks live inside `material.scss` and
inside the component
+partials that need palette-index swaps. No app-level `styles.scss` needs to
call any material
+mixin a second time for dark mode.
+
+### Token sources
+
+| Token | Example | Mode-aware?
|
+| --------------- | ------------------------------------- |
---------------------------------------------------------- |
+| Material system | `--mat-sys-primary` | Yes —
`mat.theme()` resolves differently under `.darkMode` |
+| NiFi-specific | `--nf-success-default` | Yes — rebound
under `.darkMode` in `material.scss` |
+| Raw palette | `--md-ref-palette-neutral-variant-60` | No — fixed index;
must swap manually in `.darkMode` |
+
+---
+
+## How `.darkMode` Works
+
+### Why most `mat.*-overrides()` do NOT need `.darkMode` in NiFi
+
+Angular Material's `mat.theme-overrides()` sets component tokens (`--mdc-*`,
`--mat-*`) on `<body>`
+in dark mode. Our `mat.*-overrides()` set them on `<html>` (`:root`). Since
`<body>` is a child of
+`<html>`, the `<body>` value wins the cascade.
+
+In **openflow-ui**, this matters because our per-component colors come from
`--themed-*` tokens
+which auto-rebind under `.darkMode`. When those tokens are used inside
`mat.*-overrides()`, the
+`<body>` Material dark-theme value overrides our `:root` value unless we
re-declare in `.darkMode`.
+
+In **NiFi**, most `mat.*-overrides()` use `--mat-sys-*` tokens (e.g.,
`--mat-sys-secondary-container`).
+These tokens are themselves already set correctly for dark mode by
`mat.theme()`. Angular Material's
+dark-theme defaults for those same component tokens typically equal the
light-mode values when those
+tokens use `--mat-sys-*` references, so no explicit `.darkMode` is needed.
+
+### When NiFi DOES need `.darkMode`
+
+A `.darkMode` block is needed when a `mat.*-overrides()` call hard-codes a
**raw palette index**
+(`--md-ref-palette-neutral-variant-N`) that must resolve to a **different
index** in dark mode.
+
+**Example** (`_snackbar.scss`):
+
+```scss
+:root {
+ @include mat.snack-bar-overrides(
+ (
+ button-color: var(--md-ref-palette-secondary-80),
+ // light: pale blue-grey
+ )
+ );
+}
+
+// The snackbar action button uses a fixed hex in dark mode (#004849, a dark
teal)
+// rather than a palette variable. This is the only way to express this design
intent.
+.darkMode {
+ @include mat.snack-bar-overrides(
+ (
+ button-color: #004849
+ )
+ );
+}
+```
+
+**Example with palette index swap** (`_checkbox.scss`):
+
+```scss
+:root {
+ .tertiary-checkbox {
+ @include mat.checkbox-overrides(
+ (
+ selected-icon-color: var(--md-ref-palette-tertiary-40),
+ // light: medium brown
+ )
+ );
+ }
+}
+
+// Tertiary palette index 40 is too dark in dark mode; index 70 (lighter) is
correct.
+.darkMode {
+ .tertiary-checkbox {
+ @include mat.checkbox-overrides(
+ (
+ selected-icon-color: var(--md-ref-palette-tertiary-70)
+ )
+ );
+ }
+}
+```
+
+Partials that follow this pattern: `_button.scss`, `_checkbox.scss`,
+`_progress-spinner.scss`, `_snackbar.scss`.
+
+### The DOM inheritance problem (context for code reviewers)
+
+If you see a `.darkMode` block in a NiFi partial that mirrors its `:root`
block byte-for-byte,
+where every value uses `--mat-sys-*` or `--nf-*` tokens, that block is
redundant and should be
+removed. The `--mat-sys-*` and `--nf-*` variables are already rebound for dark
mode at the
+`material.scss` level, making the duplication emit the same CSS twice without
changing any
+computed values.
+
+The canonical rule: **only raw palette index swaps belong in NiFi `.darkMode`
blocks**.
+
+---
+
+## Decision Tree: Does This Need a `.darkMode` Block?
+
+```
+Is this property non-color?
+(size, height, width, weight, tracking, line-height, shape,
+ padding, spacing, opacity, transform, etc.)
+ │
+ ├─ YES → Do NOT put it in .darkMode. Same in both modes.
+ │
+ └─ NO (color-related) → Continue ↓
+
+Does the value use --mat-sys-* or --nf-* tokens?
+ │
+ ├─ YES → These tokens resolve correctly for the current mode.
+ │ No .darkMode block needed.
+ │
+ └─ NO → Is it a raw palette index --md-ref-palette-*-N ?
+ │
+ ├─ YES → Does dark mode need a DIFFERENT index?
+ │ ├─ YES → Add .darkMode with the alternate index.
+ │ └─ NO → No .darkMode needed.
+ │
+ └─ NO (raw px, rgba, or keyword) → Evaluate case by case.
+ Plain rgba() box-shadow values do not change per mode
+ (e.g., _date-picker.scss). No .darkMode needed.
+```
+
+### Quick reference
+
+| Scenario |
`.darkMode` needed? |
+| ----------------------------------------------------------------------- |
------------------------------ |
+| `mat.*-overrides()` with `--mat-sys-*` tokens |
**No** — tokens are mode-aware |
+| `mat.*-overrides()` with `--nf-*` tokens |
**No** — tokens are mode-aware |
+| `mat.*-overrides()` with raw `--md-ref-palette-*-N` that flips per mode |
**Yes** |
+| `mat.*-overrides()` with size, shape, typography |
**No** — same in both modes |
+| Plain CSS `background-color: var(--mat-sys-surface)` |
**No** — auto-resolves |
+| Byte-for-byte duplicate of `:root` block |
**No** — redundant, delete it |
+
+---
+
+## Component Style Ownership
+
+Each component owns its own styles in its `*.component.scss` file. There are
**no** component-theme
+mixin registrations in any app's `styles.scss`.
+
+### What lives where
+
+| Style type
| Location |
+| ----------------------------------------------------------------------------
| ---------------------------------------------------------------------- |
+| Angular Material palette, system tokens (`--mat-sys-*`), `mat.*-overrides()`
| `themes/components/_*.scss` partials, orchestrated by `material.scss` |
+| App structural resets (html/body, link styles, utility classes)
| Inlined directly in `material.scss` |
+| Table and Prism syntax highlighting styles
| `themes/components/_table.scss`, `themes/components/_prism-theme.scss` |
+| Tailwind v4 `@theme` configuration
| `themes/_tailwind-theme.scss` |
+| Component-specific layout, sizing, and color overrides
| `*.component.scss` (co-located with the component) |
+
+### `styles.scss` is a framework orchestrator only
+
+Each app's `styles.scss` contains exactly these entries and nothing else:
+
+```scss
+@use 'sass:meta';
+@use 'tailwindcss';
+@use 'libs/shared/src/assets/themes/tailwind-theme';
+@use 'libs/shared/src/assets/fonts/flowfont/flowfont.css';
+@use 'libs/shared/src/assets/themes/material';
+
+@layer base {
+ @include meta.load-css('font-awesome');
+}
+
+@source #{"'libs/shared/src'"};
+```
+
+**There is no `html {}` block, no `@include component.generate-theme()`, and no
+`.darkMode` double-call block in any `styles.scss`.** Dark-mode behavior is
handled entirely
+inside `material.scss` and its component partials.
+
+---
+
+## Styling Dynamically Created Elements (`::ng-deep`)
+
+Angular's emulated view encapsulation adds `[_ngcontent-xxx]` attributes to
elements defined in
+a component's template, scoping that component's styles to those elements
only. Elements created
+programmatically (e.g., via D3 or `document.createElement()`) do NOT receive
those attributes, so
+component-scoped styles cannot reach them.
+
+**Pattern:** Use `::ng-deep` in a component's stylesheet to pierce
encapsulation:
+
+```scss
+// birdseye.component.scss
+:host ::ng-deep #birdseye {
+ width: 266px;
+ height: 150px;
+ // structural styles only
+}
+```
+
+**Rules for `::ng-deep` + dark mode:**
+
+| Situation | `.darkMode` block inside
`::ng-deep`? |
+| --------------------------------------------- |
----------------------------------------------- |
+| Structural / layout rules only | **No** — no color involved
|
+| Colors using `--mat-sys-*` or `--nf-*` tokens | **No** — tokens auto-resolve
|
+| Colors using raw `--md-ref-palette-*-N` | **Yes** — add internal
`.darkMode` for the swap |
+
+NiFi's `canvas.component.scss` and `birdseye.component.scss` only contain
structural layout rules
+inside `::ng-deep`. Colors use `--mat-sys-*` and `--nf-*` CSS custom
properties that already
+resolve correctly for both light and dark mode. No `.darkMode` block is needed
inside `::ng-deep`
+for these components.
+
+---
+
+## File Structure
+
+```
+themes/
+├── README.md ← this file
+├── material.scss ← orchestrator: structural resets, palette,
mat.theme(), imports all partials
+├── _tailwind-theme.scss ← Tailwind v4 @theme configuration (font sizes,
etc.)
+├── purple.scss ← alternative purple theme (not used in production)
Review Comment:
`purple.scss` is deleted by this commit — should be removed from the
file-structure tree.
##########
nifi-frontend/src/main/frontend/apps/nifi/src/app/pages/flow-designer/ui/canvas/canvas.component.scss:
##########
@@ -402,3 +409,373 @@
font-size: 10px;
}
}
+
+// Shadows should always be darker. We explicitly set this so the SVG shadows
are correct in both modes.
+$drop-shadow-color: black;
+
+:host ::ng-deep svg.canvas-svg {
Review Comment:
Cosmetic: this is a second `:host ::ng-deep svg.canvas-svg { … }` block —
there's already one at line 46. Now that they're co-located in the same file,
worth merging into a single block. Easier to scan and avoids the impression
that they have different scoping intent.
##########
nifi-frontend/src/main/frontend/libs/shared/src/assets/themes/README.md:
##########
@@ -0,0 +1,353 @@
+<!--
+ Licensed to the Apache Software Foundation (ASF) under one or more
+ contributor license agreements. See the NOTICE file distributed with
+ this work for additional information regarding copyright ownership.
+ The ASF licenses this file to You under the Apache License, Version 2.0
+ (the "License"); you may not use this file except in compliance with
+ the License. You may obtain a copy of the License at
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+-->
+
+# Theme Architecture
+
+This directory contains the Angular Material theming layer for the NiFi
frontend.
+
+---
+
+## Contents
+
+- [Design System Overview](#design-system-overview)
+- [Theme Stack](#theme-stack)
+- [How `.darkMode` Works](#how-darkmode-works)
+- [Decision Tree: Does This Need a `.darkMode`
Block?](#decision-tree-does-this-need-a-darkmode-block)
+- [Component Style Ownership](#component-style-ownership)
+- [Styling Dynamically Created Elements
(`::ng-deep`)](#styling-dynamically-created-elements-ng-deep)
+- [File Structure](#file-structure)
+
+---
+
+## Design System Overview
+
+The NiFi UI uses [Angular Material](https://material.angular.io/) which
implements Google's
+[Material Design 3](https://m3.material.io/) specification. The theme applies
a minimally
+customized MD3 appearance — functional and accessible, without a proprietary
design token layer.
+
+Snowflake's fork (`openflow-ui`) sits on top of this same Angular Material
base but replaces the
+palette values with Snowflake's Stellar design system tokens (Balto). Code
flows in both directions
+between the repositories, so it is important to understand where the two
implementations differ.
+
+---
+
+## Theme Stack
+
+```
+md-ref-palette-* values (defined once in material.scss for light; swapped in
.darkMode for dark)
+ ↓
+mat.theme() + mat.theme-overrides() → --mat-sys-* system tokens
+ ↓
+per-component partials: mat.*-overrides() + plain CSS using --mat-sys-*, --nf-*
+ ↓
+Rendered UI
+```
+
+### Entry point: `material.scss`
+
+`material.scss` is the orchestrator. It:
+
+1. Defines the MD3 palette via `--md-ref-palette-*` values.
+2. Calls `mat.theme()` once to generate all `--mat-sys-*` system tokens.
+3. Calls `generate-material-theme()` from each component partial to apply
per-component overrides.
+
+`material.scss` is loaded via `@use` in each app's `styles.scss`. Its dark
theme is
+self-contained — the `.darkMode {}` blocks live inside `material.scss` and
inside the component
+partials that need palette-index swaps. No app-level `styles.scss` needs to
call any material
+mixin a second time for dark mode.
+
+### Token sources
+
+| Token | Example | Mode-aware?
|
+| --------------- | ------------------------------------- |
---------------------------------------------------------- |
+| Material system | `--mat-sys-primary` | Yes —
`mat.theme()` resolves differently under `.darkMode` |
+| NiFi-specific | `--nf-success-default` | Yes — rebound
under `.darkMode` in `material.scss` |
+| Raw palette | `--md-ref-palette-neutral-variant-60` | No — fixed index;
must swap manually in `.darkMode` |
+
+---
+
+## How `.darkMode` Works
+
+### Why most `mat.*-overrides()` do NOT need `.darkMode` in NiFi
+
+Angular Material's `mat.theme-overrides()` sets component tokens (`--mdc-*`,
`--mat-*`) on `<body>`
+in dark mode. Our `mat.*-overrides()` set them on `<html>` (`:root`). Since
`<body>` is a child of
+`<html>`, the `<body>` value wins the cascade.
+
+In **openflow-ui**, this matters because our per-component colors come from
`--themed-*` tokens
+which auto-rebind under `.darkMode`. When those tokens are used inside
`mat.*-overrides()`, the
+`<body>` Material dark-theme value overrides our `:root` value unless we
re-declare in `.darkMode`.
+
+In **NiFi**, most `mat.*-overrides()` use `--mat-sys-*` tokens (e.g.,
`--mat-sys-secondary-container`).
+These tokens are themselves already set correctly for dark mode by
`mat.theme()`. Angular Material's
+dark-theme defaults for those same component tokens typically equal the
light-mode values when those
+tokens use `--mat-sys-*` references, so no explicit `.darkMode` is needed.
+
+### When NiFi DOES need `.darkMode`
+
+A `.darkMode` block is needed when a `mat.*-overrides()` call hard-codes a
**raw palette index**
+(`--md-ref-palette-neutral-variant-N`) that must resolve to a **different
index** in dark mode.
+
+**Example** (`_snackbar.scss`):
+
+```scss
+:root {
+ @include mat.snack-bar-overrides(
+ (
+ button-color: var(--md-ref-palette-secondary-80),
+ // light: pale blue-grey
+ )
+ );
+}
+
+// The snackbar action button uses a fixed hex in dark mode (#004849, a dark
teal)
+// rather than a palette variable. This is the only way to express this design
intent.
+.darkMode {
+ @include mat.snack-bar-overrides(
+ (
+ button-color: #004849
+ )
+ );
+}
+```
+
+**Example with palette index swap** (`_checkbox.scss`):
+
+```scss
+:root {
+ .tertiary-checkbox {
+ @include mat.checkbox-overrides(
+ (
+ selected-icon-color: var(--md-ref-palette-tertiary-40),
+ // light: medium brown
+ )
+ );
+ }
+}
+
+// Tertiary palette index 40 is too dark in dark mode; index 70 (lighter) is
correct.
+.darkMode {
+ .tertiary-checkbox {
+ @include mat.checkbox-overrides(
+ (
+ selected-icon-color: var(--md-ref-palette-tertiary-70)
+ )
+ );
+ }
+}
+```
+
+Partials that follow this pattern: `_button.scss`, `_checkbox.scss`,
+`_progress-spinner.scss`, `_snackbar.scss`.
+
+### The DOM inheritance problem (context for code reviewers)
+
+If you see a `.darkMode` block in a NiFi partial that mirrors its `:root`
block byte-for-byte,
+where every value uses `--mat-sys-*` or `--nf-*` tokens, that block is
redundant and should be
+removed. The `--mat-sys-*` and `--nf-*` variables are already rebound for dark
mode at the
+`material.scss` level, making the duplication emit the same CSS twice without
changing any
+computed values.
+
+The canonical rule: **only raw palette index swaps belong in NiFi `.darkMode`
blocks**.
+
+---
+
+## Decision Tree: Does This Need a `.darkMode` Block?
+
+```
+Is this property non-color?
+(size, height, width, weight, tracking, line-height, shape,
+ padding, spacing, opacity, transform, etc.)
+ │
+ ├─ YES → Do NOT put it in .darkMode. Same in both modes.
+ │
+ └─ NO (color-related) → Continue ↓
+
+Does the value use --mat-sys-* or --nf-* tokens?
+ │
+ ├─ YES → These tokens resolve correctly for the current mode.
+ │ No .darkMode block needed.
+ │
+ └─ NO → Is it a raw palette index --md-ref-palette-*-N ?
+ │
+ ├─ YES → Does dark mode need a DIFFERENT index?
+ │ ├─ YES → Add .darkMode with the alternate index.
+ │ └─ NO → No .darkMode needed.
+ │
+ └─ NO (raw px, rgba, or keyword) → Evaluate case by case.
+ Plain rgba() box-shadow values do not change per mode
+ (e.g., _date-picker.scss). No .darkMode needed.
+```
+
+### Quick reference
+
+| Scenario |
`.darkMode` needed? |
+| ----------------------------------------------------------------------- |
------------------------------ |
+| `mat.*-overrides()` with `--mat-sys-*` tokens |
**No** — tokens are mode-aware |
+| `mat.*-overrides()` with `--nf-*` tokens |
**No** — tokens are mode-aware |
+| `mat.*-overrides()` with raw `--md-ref-palette-*-N` that flips per mode |
**Yes** |
+| `mat.*-overrides()` with size, shape, typography |
**No** — same in both modes |
+| Plain CSS `background-color: var(--mat-sys-surface)` |
**No** — auto-resolves |
+| Byte-for-byte duplicate of `:root` block |
**No** — redundant, delete it |
+
+---
+
+## Component Style Ownership
+
+Each component owns its own styles in its `*.component.scss` file. There are
**no** component-theme
+mixin registrations in any app's `styles.scss`.
+
+### What lives where
+
+| Style type
| Location |
+| ----------------------------------------------------------------------------
| ---------------------------------------------------------------------- |
+| Angular Material palette, system tokens (`--mat-sys-*`), `mat.*-overrides()`
| `themes/components/_*.scss` partials, orchestrated by `material.scss` |
+| App structural resets (html/body, link styles, utility classes)
| Inlined directly in `material.scss` |
+| Table and Prism syntax highlighting styles
| `themes/components/_table.scss`, `themes/components/_prism-theme.scss` |
+| Tailwind v4 `@theme` configuration
| `themes/_tailwind-theme.scss` |
+| Component-specific layout, sizing, and color overrides
| `*.component.scss` (co-located with the component) |
+
+### `styles.scss` is a framework orchestrator only
+
+Each app's `styles.scss` contains exactly these entries and nothing else:
+
+```scss
+@use 'sass:meta';
+@use 'tailwindcss';
+@use 'libs/shared/src/assets/themes/tailwind-theme';
Review Comment:
This template line doesn't match what actually shipped — no app's
`styles.scss` imports `tailwind-theme` directly anymore.
`tailwind-theme.configure` is now invoked from inside `material.scss` (line
~932). Worth removing this `@use` from the template so the README matches
reality.
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: [email protected]
For queries about this service, please contact Infrastructure at:
[email protected]
