feat(themes): add built-in holiday theme 🎁 (#14301)

Co-authored-by: jacob314 <jacob314@gmail.com>

packages/cli/src/ui/themes/holiday.ts

@@ -0,0 +1,169 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { type ColorsTheme, Theme } from './theme.js';
+import { interpolateColor } from './color-utils.js';
+
+const holidayColors: ColorsTheme = {
+  type: 'dark',
+  Background: '#00210e',
+  Foreground: '#F0F8FF',
+  LightBlue: '#B0E0E6',
+  AccentBlue: '#3CB371',
+  AccentPurple: '#FF9999',
+  AccentCyan: '#33F9FF',
+  AccentGreen: '#3CB371',
+  AccentYellow: '#FFEE8C',
+  AccentRed: '#FF6347',
+  DiffAdded: '#2E8B57',
+  DiffRemoved: '#CD5C5C',
+  Comment: '#8FBC8F',
+  Gray: '#D7F5D3',
+  DarkGray: interpolateColor('#D7F5D3', '#151B18', 0.5),
+  GradientColors: ['#FF0000', '#FFFFFF', '#008000'],
+};
+
+export const Holiday: Theme = new Theme(
+  'Holiday',
+  'dark',
+  {
+    hljs: {
+      display: 'block',
+      overflowX: 'auto',
+      padding: '0.5em',
+      background: holidayColors.Background,
+      color: holidayColors.Foreground,
+    },
+    'hljs-keyword': {
+      color: holidayColors.AccentBlue,
+    },
+    'hljs-literal': {
+      color: holidayColors.AccentBlue,
+    },
+    'hljs-symbol': {
+      color: holidayColors.AccentBlue,
+    },
+    'hljs-name': {
+      color: holidayColors.AccentBlue,
+    },
+    'hljs-link': {
+      color: holidayColors.AccentBlue,
+      textDecoration: 'underline',
+    },
+    'hljs-built_in': {
+      color: holidayColors.AccentCyan,
+    },
+    'hljs-type': {
+      color: holidayColors.AccentCyan,
+    },
+    'hljs-number': {
+      color: holidayColors.AccentGreen,
+    },
+    'hljs-class': {
+      color: holidayColors.AccentGreen,
+    },
+    'hljs-string': {
+      color: holidayColors.AccentYellow,
+    },
+    'hljs-meta-string': {
+      color: holidayColors.AccentYellow,
+    },
+    'hljs-regexp': {
+      color: holidayColors.AccentRed,
+    },
+    'hljs-template-tag': {
+      color: holidayColors.AccentRed,
+    },
+    'hljs-subst': {
+      color: holidayColors.Foreground,
+    },
+    'hljs-function': {
+      color: holidayColors.Foreground,
+    },
+    'hljs-title': {
+      color: holidayColors.Foreground,
+    },
+    'hljs-params': {
+      color: holidayColors.Foreground,
+    },
+    'hljs-formula': {
+      color: holidayColors.Foreground,
+    },
+    'hljs-comment': {
+      color: holidayColors.Comment,
+      fontStyle: 'italic',
+    },
+    'hljs-quote': {
+      color: holidayColors.Comment,
+      fontStyle: 'italic',
+    },
+    'hljs-doctag': {
+      color: holidayColors.Comment,
+    },
+    'hljs-meta': {
+      color: holidayColors.Gray,
+    },
+    'hljs-meta-keyword': {
+      color: holidayColors.Gray,
+    },
+    'hljs-tag': {
+      color: holidayColors.Gray,
+    },
+    'hljs-variable': {
+      color: holidayColors.AccentPurple,
+    },
+    'hljs-template-variable': {
+      color: holidayColors.AccentPurple,
+    },
+    'hljs-attr': {
+      color: holidayColors.LightBlue,
+    },
+    'hljs-attribute': {
+      color: holidayColors.LightBlue,
+    },
+    'hljs-builtin-name': {
+      color: holidayColors.LightBlue,
+    },
+    'hljs-section': {
+      color: holidayColors.AccentYellow,
+    },
+    'hljs-emphasis': {
+      fontStyle: 'italic',
+    },
+    'hljs-strong': {
+      fontWeight: 'bold',
+    },
+    'hljs-bullet': {
+      color: holidayColors.AccentYellow,
+    },
+    'hljs-selector-tag': {
+      color: holidayColors.AccentYellow,
+    },
+    'hljs-selector-id': {
+      color: holidayColors.AccentYellow,
+    },
+    'hljs-selector-class': {
+      color: holidayColors.AccentYellow,
+    },
+    'hljs-selector-attr': {
+      color: holidayColors.AccentYellow,
+    },
+    'hljs-selector-pseudo': {
+      color: holidayColors.AccentYellow,
+    },
+    'hljs-addition': {
+      backgroundColor: holidayColors.DiffAdded,
+      display: 'inline-block',
+      width: '100%',
+    },
+    'hljs-deletion': {
+      backgroundColor: holidayColors.DiffRemoved,
+      display: 'inline-block',
+      width: '100%',
+    },
+  },
+  holidayColors,
+);

packages/cli/src/ui/themes/theme-manager.ts

@@ -11,6 +11,7 @@ import { Dracula } from './dracula.js';
 import { GitHubDark } from './github-dark.js';
 import { GitHubLight } from './github-light.js';
 import { GoogleCode } from './googlecode.js';
+import { Holiday } from './holiday.js';
 import { DefaultLight } from './default-light.js';
 import { DefaultDark } from './default.js';
 import { ShadesOfPurple } from './shades-of-purple.js';
@@ -51,6 +52,7 @@ class ThemeManager {
       GitHubDark,
       GitHubLight,
       GoogleCode,
+      Holiday,
       ShadesOfPurple,
       XCode,
       ANSI,