feat: style editor for blog

src/main/engine/MetaEngine.ts

@@ -5,6 +5,7 @@ import { app } from 'electron';
 import { eq } from 'drizzle-orm';
 import { getDatabase } from '../database';
 import { posts, projects } from '../database/schema';
+import { sanitizePicoTheme, type PicoThemeName } from '../shared/picoThemes';
 import {
   normalizeTaxonomyTerm,
   normalizeNonEmptyTaxonomyTerm,
@@ -22,6 +23,7 @@ export interface ProjectMetadata {
   mainLanguage?: string; // Main language for AI-generated content (ISO code, e.g., 'en', 'de', 'es')
   defaultAuthor?: string; // Default author for new posts and media
   maxPostsPerPage?: number; // Preview/server maximum posts per page (default 50)
+  picoTheme?: PicoThemeName; // Selected Pico CSS theme for preview/rendering
 }
 
 const DEFAULT_MAX_POSTS_PER_PAGE = 50;
@@ -61,10 +63,12 @@ function sanitizePublicUrl(value: unknown): string | undefined {
 function normalizeProjectMetadata(metadata: ProjectMetadata): ProjectMetadata {
   const maxPostsPerPage = sanitizeMaxPostsPerPage(metadata.maxPostsPerPage);
   const publicUrl = sanitizePublicUrl(metadata.publicUrl);
+  const picoTheme = sanitizePicoTheme(metadata.picoTheme);
   return {
     ...metadata,
     publicUrl,
     maxPostsPerPage,
+    picoTheme,
   };
 }
 
@@ -179,6 +183,9 @@ export class MetaEngine extends EventEmitter {
     if (updates.maxPostsPerPage !== undefined) {
       normalizedUpdates.maxPostsPerPage = sanitizeMaxPostsPerPage(updates.maxPostsPerPage);
     }
+    if (updates.picoTheme !== undefined) {
+      normalizedUpdates.picoTheme = sanitizePicoTheme(updates.picoTheme);
+    }
 
     if (!this.projectMetadata) {
       this.projectMetadata = normalizeProjectMetadata({
@@ -189,6 +196,7 @@ export class MetaEngine extends EventEmitter {
         mainLanguage: normalizedUpdates.mainLanguage,
         defaultAuthor: normalizedUpdates.defaultAuthor,
         maxPostsPerPage: normalizedUpdates.maxPostsPerPage,
+        picoTheme: normalizedUpdates.picoTheme,
       });
     } else {
       this.projectMetadata = normalizeProjectMetadata({

src/main/engine/PageRenderer.ts

@@ -3,6 +3,7 @@ import { marked } from 'marked';
 import { Liquid } from 'liquidjs';
 import type { MediaData } from './MediaEngine';
 import type { PostData } from './PostEngine';
+import { PICO_THEME_NAMES } from '../shared/picoThemes';
 
 export interface HtmlRewriteContext {
   canonicalPostPathBySlug: Map<string, string>;
@@ -41,6 +42,8 @@ export type DateArchiveContext = {
 export interface PostListTemplateContext {
   page_title: string;
   language: string;
+  pico_stylesheet_href?: string;
+  html_theme_attribute?: string;
   is_date_archive: boolean;
   show_archive_range_heading: boolean;
   archive_context: {
@@ -67,6 +70,8 @@ export interface PostListTemplateContext {
 export interface SinglePostTemplateContext {
   page_title: string;
   language: string;
+  pico_stylesheet_href?: string;
+  html_theme_attribute?: string;
   post: TemplatePostEntry;
   canonical_post_path_by_slug: Record<string, string>;
   canonical_media_path_by_source_path: Record<string, string>;
@@ -75,6 +80,8 @@ export interface SinglePostTemplateContext {
 export interface NotFoundTemplateContext {
   page_title: string;
   language: string;
+  pico_stylesheet_href?: string;
+  html_theme_attribute?: string;
 }
 
 export interface RoutePagination {
@@ -96,11 +103,20 @@ export interface PostEngineContract {
   getPost: (id: string) => Promise<PostData | null>;
 }
 
-export const PREVIEW_ASSETS = {
+export const PREVIEW_ASSETS: Record<string, { modulePath: string; contentType: string }> = {
   'pico.min.css': {
     modulePath: '@picocss/pico/css/pico.min.css',
     contentType: 'text/css; charset=utf-8',
   },
+  ...Object.fromEntries(
+    PICO_THEME_NAMES.map((theme) => [
+      `pico.${theme}.min.css`,
+      {
+        modulePath: `@picocss/pico/css/pico.${theme}.min.css`,
+        contentType: 'text/css; charset=utf-8',
+      },
+    ])
+  ),
   'lightbox.min.css': {
     modulePath: 'lightbox2/dist/css/lightbox.min.css',
     contentType: 'text/css; charset=utf-8',
@@ -109,7 +125,7 @@ export const PREVIEW_ASSETS = {
     modulePath: 'lightbox2/dist/js/lightbox-plus-jquery.min.js',
     contentType: 'application/javascript; charset=utf-8',
   },
-} as const;
+};
 
 export const PREVIEW_IMAGE_ASSETS = {
   'prev.png': {
@@ -616,6 +632,8 @@ export class PageRenderer {
       basePathname: string;
       page_title: string;
       language: string;
+      pico_stylesheet_href?: string;
+      html_theme_attribute?: string;
       pagination?: PaginationContext;
     },
   ): PostListTemplateContext {
@@ -710,6 +728,8 @@ export class PageRenderer {
     return {
       page_title: options.page_title,
       language: options.language,
+      pico_stylesheet_href: options.pico_stylesheet_href,
+      html_theme_attribute: options.html_theme_attribute,
       is_date_archive: options.routeKind === 'date',
       show_archive_range_heading: hasRangeHeading,
       archive_context: options.routeKind === 'date'
@@ -763,6 +783,8 @@ export class PageRenderer {
       basePathname: string;
       page_title: string;
       language: string;
+      pico_stylesheet_href?: string;
+      html_theme_attribute?: string;
       pagination?: PaginationContext;
     },
     postEngine?: PostEngineContract,
@@ -786,7 +808,7 @@ export class PageRenderer {
   async renderSinglePost(
     post: PostData,
     rewriteContext: HtmlRewriteContext,
-    pageContext: { page_title: string; language: string },
+    pageContext: { page_title: string; language: string; pico_stylesheet_href?: string; html_theme_attribute?: string },
     postEngine?: PostEngineContract,
   ): Promise<string> {
     const renderablePost = postEngine

src/main/engine/PreviewServer.ts

@@ -18,6 +18,7 @@ import {
   type MediaEngineContract,
   type PostMediaEngineContract,
 } from './PageRenderer';
+import { getPicoStylesheetHref, sanitizePicoTheme, sanitizePicoThemeMode } from '../shared/picoThemes';
 
 interface ActiveProjectContext {
   projectId: string;
@@ -172,11 +173,25 @@ export class PreviewServer {
       const language = metadata?.mainLanguage?.trim() || 'en';
       const pageTitle = resolvePageTitle(metadata, context.projectName, context.projectDescription);
       const maxPostsPerPage = clampMaxPostsPerPage(metadata?.maxPostsPerPage);
-      const htmlRewriteContext = await this.buildHtmlRewriteContext();
-
       const requestUrl = new URL(req.url || '/', 'http://127.0.0.1');
+      const requestTheme = sanitizePicoTheme(requestUrl.searchParams.get('theme'));
+      const previewThemeMode = sanitizePicoThemeMode(requestUrl.searchParams.get('mode'));
+      const appliedTheme = requestTheme ?? sanitizePicoTheme((metadata as { picoTheme?: unknown } | null)?.picoTheme);
+      const picoStylesheetHref = getPicoStylesheetHref(appliedTheme);
+      const htmlRewriteContext = await this.buildHtmlRewriteContext();
       const pathname = decodeURIComponent(requestUrl.pathname.replace(/\/+$/, '') || '/');
 
+      if (pathname === '/__style-preview') {
+        const stylePreviewHtml = await this.renderStylePreview(htmlRewriteContext, {
+          pageTitle,
+          language,
+          picoStylesheetHref,
+          htmlThemeAttribute: previewThemeMode && previewThemeMode !== 'auto' ? `data-theme="${previewThemeMode}"` : undefined,
+        });
+        this.respond(res, 200, stylePreviewHtml);
+        return;
+      }
+
       const asset = await this.resolveAsset(pathname);
       if (asset) {
         this.respondAsset(res, asset.contentType, asset.body);
@@ -198,11 +213,15 @@ export class PreviewServer {
       const result = await this.resolveRoute(pathname, maxPostsPerPage, htmlRewriteContext, {
         pageTitle,
         language,
+        picoStylesheetHref,
+        htmlThemeAttribute: undefined,
       });
       if (!result) {
         const notFoundHtml = await this.pageRenderer.renderNotFound({
           page_title: '404 Not Found',
           language,
+          pico_stylesheet_href: picoStylesheetHref,
+          html_theme_attribute: undefined,
         });
         this.respond(res, 404, notFoundHtml);
         return;
@@ -219,7 +238,7 @@ export class PreviewServer {
     pathname: string,
     maxPostsPerPage: number,
     rewriteContext: HtmlRewriteContext,
-    pageContext: { pageTitle: string; language: string },
+    pageContext: { pageTitle: string; language: string; picoStylesheetHref: string; htmlThemeAttribute?: string },
   ): Promise<string | null> {
     const routePagination = parseRoutePagination(pathname);
     if (!routePagination) {
@@ -244,6 +263,8 @@ export class PreviewServer {
       return this.pageRenderer.renderSinglePost(post, rewriteContext, {
         page_title: pageContext.pageTitle,
         language: pageContext.language,
+        pico_stylesheet_href: pageContext.picoStylesheetHref,
+        html_theme_attribute: pageContext.htmlThemeAttribute,
       }, this.postEngine);
     }
 
@@ -255,6 +276,8 @@ export class PreviewServer {
       return this.pageRenderer.renderSinglePost(post, rewriteContext, {
         page_title: pageContext.pageTitle,
         language: pageContext.language,
+        pico_stylesheet_href: pageContext.picoStylesheetHref,
+        html_theme_attribute: pageContext.htmlThemeAttribute,
       }, this.postEngine);
     }
 
@@ -269,6 +292,8 @@ export class PreviewServer {
       return this.pageRenderer.renderSinglePost(post, rewriteContext, {
         page_title: pageContext.pageTitle,
         language: pageContext.language,
+        pico_stylesheet_href: pageContext.picoStylesheetHref,
+        html_theme_attribute: pageContext.htmlThemeAttribute,
       }, this.postEngine);
     }
 
@@ -280,6 +305,8 @@ export class PreviewServer {
       return this.pageRenderer.renderSinglePost(post, rewriteContext, {
         page_title: pageContext.pageTitle,
         language: pageContext.language,
+        pico_stylesheet_href: pageContext.picoStylesheetHref,
+        html_theme_attribute: pageContext.htmlThemeAttribute,
       }, this.postEngine);
     }
 
@@ -293,6 +320,8 @@ export class PreviewServer {
         pagination: { page, maxPostsPerPage, totalPosts: result.totalPosts },
         page_title: pageContext.pageTitle,
         language: pageContext.language,
+        pico_stylesheet_href: pageContext.picoStylesheetHref,
+        html_theme_attribute: pageContext.htmlThemeAttribute,
       }, this.postEngine);
     }
 
@@ -308,6 +337,8 @@ export class PreviewServer {
         pagination: { page, maxPostsPerPage, totalPosts: result.totalPosts },
         page_title: pageContext.pageTitle,
         language: pageContext.language,
+        pico_stylesheet_href: pageContext.picoStylesheetHref,
+        html_theme_attribute: pageContext.htmlThemeAttribute,
       }, this.postEngine);
     }
 
@@ -323,6 +354,8 @@ export class PreviewServer {
         pagination: { page, maxPostsPerPage, totalPosts: result.totalPosts },
         page_title: pageContext.pageTitle,
         language: pageContext.language,
+        pico_stylesheet_href: pageContext.picoStylesheetHref,
+        html_theme_attribute: pageContext.htmlThemeAttribute,
       }, this.postEngine);
     }
 
@@ -338,6 +371,8 @@ export class PreviewServer {
       return this.pageRenderer.renderSinglePost(post, rewriteContext, {
         page_title: pageContext.pageTitle,
         language: pageContext.language,
+        pico_stylesheet_href: pageContext.picoStylesheetHref,
+        html_theme_attribute: pageContext.htmlThemeAttribute,
       }, this.postEngine);
     }
 
@@ -355,6 +390,8 @@ export class PreviewServer {
         pagination: { page, maxPostsPerPage, totalPosts: result.totalPosts },
         page_title: pageContext.pageTitle,
         language: pageContext.language,
+        pico_stylesheet_href: pageContext.picoStylesheetHref,
+        html_theme_attribute: pageContext.htmlThemeAttribute,
       }, this.postEngine);
     }
 
@@ -372,6 +409,8 @@ export class PreviewServer {
         pagination: { page, maxPostsPerPage, totalPosts: result.totalPosts },
         page_title: pageContext.pageTitle,
         language: pageContext.language,
+        pico_stylesheet_href: pageContext.picoStylesheetHref,
+        html_theme_attribute: pageContext.htmlThemeAttribute,
       }, this.postEngine);
     }
 
@@ -387,6 +426,8 @@ export class PreviewServer {
         pagination: { page, maxPostsPerPage, totalPosts: result.totalPosts },
         page_title: pageContext.pageTitle,
         language: pageContext.language,
+        pico_stylesheet_href: pageContext.picoStylesheetHref,
+        html_theme_attribute: pageContext.htmlThemeAttribute,
       }, this.postEngine);
     }
 
@@ -399,12 +440,45 @@ export class PreviewServer {
       return this.pageRenderer.renderSinglePost(pagePost, rewriteContext, {
         page_title: pageContext.pageTitle,
         language: pageContext.language,
+        pico_stylesheet_href: pageContext.picoStylesheetHref,
+        html_theme_attribute: pageContext.htmlThemeAttribute,
       }, this.postEngine);
     }
 
     return null;
   }
 
+  private async renderStylePreview(
+    rewriteContext: HtmlRewriteContext,
+    pageContext: { pageTitle: string; language: string; picoStylesheetHref: string; htmlThemeAttribute?: string },
+  ): Promise<string> {
+    const result = await this.loadPublishedSnapshotsPage({ status: 'published' }, {
+      maxPostsPerPage: 10,
+      page: 1,
+    });
+
+    if (result.posts.length === 0) {
+      return this.pageRenderer.renderNotFound({
+        page_title: pageContext.pageTitle,
+        language: pageContext.language,
+        pico_stylesheet_href: pageContext.picoStylesheetHref,
+        html_theme_attribute: pageContext.htmlThemeAttribute,
+      });
+    }
+
+    return this.pageRenderer.renderPostList(result.posts, rewriteContext, {
+      archiveGrouping: true,
+      routeKind: 'date',
+      archiveContext: { kind: 'root' },
+      basePathname: '/__style-preview',
+      pagination: { page: 1, maxPostsPerPage: 10, totalPosts: result.totalPosts },
+      page_title: pageContext.pageTitle,
+      language: pageContext.language,
+      pico_stylesheet_href: pageContext.picoStylesheetHref,
+      html_theme_attribute: pageContext.htmlThemeAttribute,
+    }, this.postEngine);
+  }
+
   private async findPublishedPostBySlug(slug: string, dateFilter?: { year: number; month: number }): Promise<PostData | null> {
     if (!slug) return null;
 
@@ -588,7 +662,7 @@ export class PreviewServer {
     const match = pathname.match(/^\/assets\/([^/]+)$/);
     if (!match) return null;
 
-    const assetName = match[1] as keyof typeof PREVIEW_ASSETS;
+    const assetName = match[1];
     const assetDefinition = PREVIEW_ASSETS[assetName];
     if (!assetDefinition) return null;
 

src/main/engine/templates/not-found.liquid

@@ -1,6 +1,6 @@
 <!doctype html>
-<html lang="{{ language }}">
+<html lang="{{ language }}"{% if html_theme_attribute %} {{ html_theme_attribute }}{% endif %}>
-  {% render 'partials/head', page_title: page_title %}
+  {% render 'partials/head', page_title: page_title, pico_stylesheet_href: pico_stylesheet_href %}
   <body>
     <main>
       <section class="not-found" data-template="not-found">

src/main/engine/templates/partials/head.liquid

@@ -2,7 +2,8 @@
   <meta charset="utf-8" />
   <meta name="viewport" content="width=device-width, initial-scale=1" />
   <title>{{ page_title }}</title>
-  <link rel="stylesheet" href="/assets/pico.min.css" />
+  {% assign resolved_pico_stylesheet_href = pico_stylesheet_href | default: '/assets/pico.min.css' %}
+  <link rel="stylesheet" href="{{ resolved_pico_stylesheet_href }}" />
   <link rel="stylesheet" href="/assets/lightbox.min.css" />
   {% render 'partials/styles' %}
   <script defer src="/assets/lightbox.min.js"></script>

src/main/engine/templates/partials/styles.liquid

@@ -1,10 +1,10 @@
 <style>
   :root { color-scheme: light dark; }
-  body { max-width: 960px; margin: 0 auto; padding: 2rem 1rem 4rem; }
+  body { max-width: 960px; margin: 0 auto; padding: 2rem 1rem 4rem; background: var(--pico-background-color, var(--background-color)); color: var(--pico-color, var(--color)); }
   main { display: grid; gap: 1rem; }
-  .post { border: 1px solid var(--muted-border-color); padding: 1rem; background: var(--card-background-color); }
+  .post { border: 1px solid var(--pico-muted-border-color, var(--muted-border-color)); padding: 1rem; background: var(--pico-card-background-color, var(--card-background-color)); }
   .post iframe { width: 100%; min-height: 20rem; }
-  .macro-gallery, .macro-photo-archive { border: 1px dashed var(--muted-border-color); padding: .75rem; margin: 1rem 0; }
+  .macro-gallery, .macro-photo-archive { border: 1px dashed var(--pico-muted-border-color, var(--muted-border-color)); padding: .75rem; margin: 1rem 0; }
   .gallery-container { display: grid; gap: .5rem; }
   .macro-gallery.gallery-cols-1 .gallery-container { grid-template-columns: 1fr; }
   .macro-gallery.gallery-cols-2 .gallery-container { grid-template-columns: repeat(2, minmax(0, 1fr)); }
@@ -14,23 +14,23 @@
   .macro-gallery.gallery-cols-6 .gallery-container { grid-template-columns: repeat(6, minmax(0, 1fr)); }
   .gallery-item, .photo-archive-item { display: block; overflow: hidden; border-radius: .25rem; }
   .gallery-item img, .photo-archive-item img { display: block; width: 100%; height: auto; aspect-ratio: 1 / 1; object-fit: cover; }
-  .gallery-caption { margin-top: .5rem; text-align: center; color: var(--muted-color); font-size: .92rem; }
+  .gallery-caption { margin-top: .5rem; text-align: center; color: var(--pico-muted-color, var(--muted-color)); font-size: .92rem; }
-  .gallery-empty, .photo-archive-empty { color: var(--muted-color); font-style: italic; }
+  .gallery-empty, .photo-archive-empty { color: var(--pico-muted-color, var(--muted-color)); font-style: italic; }
   .photo-archive-container { display: grid; gap: 1rem; }
   .photo-archive-month { display: grid; grid-template-columns: 3.25rem 1fr; gap: .75rem; align-items: start; }
   .photo-archive-month-label { display: flex; justify-content: center; align-items: center; }
-  .photo-archive-month-label span { writing-mode: vertical-rl; transform: rotate(180deg); letter-spacing: .08em; text-transform: uppercase; color: var(--muted-color); }
+  .photo-archive-month-label span { writing-mode: vertical-rl; transform: rotate(180deg); letter-spacing: .08em; text-transform: uppercase; color: var(--pico-muted-color, var(--muted-color)); }
   .photo-archive-gallery { display: grid; gap: .5rem; grid-template-columns: repeat(4, minmax(0, 1fr)); }
   .photo-archive-single-month .photo-archive-gallery { grid-template-columns: repeat(5, minmax(0, 1fr)); }
   .archive-day-group { display: grid; grid-template-columns: 5.25rem 1fr; gap: 1.25rem; align-items: stretch; }
-  .archive-day-marker { display: flex; justify-content: center; align-items: center; color: var(--muted-color); }
+  .archive-day-marker { display: flex; justify-content: center; align-items: center; color: var(--pico-muted-color, var(--muted-color)); }
   .archive-day-marker span { writing-mode: vertical-rl; transform: rotate(180deg); letter-spacing: .16em; font-size: 1.05rem; font-weight: 600; text-transform: uppercase; }
   .archive-day-posts { display: grid; gap: 1rem; }
-  .archive-day-separator { position: relative; height: 2px; width: 100%; color: var(--color); border-top: 1px solid currentColor; opacity: .18; margin: .45rem 0 .65rem; }
+  .archive-day-separator { position: relative; height: 2px; width: 100%; color: var(--pico-color, var(--color)); border-top: 1px solid currentColor; opacity: .18; margin: .45rem 0 .65rem; }
   .archive-day-separator::before { content: ''; position: absolute; inset: 0; background: linear-gradient(to right, transparent 0%, transparent 18%, currentColor 58%, transparent 92%, transparent 100%); opacity: .85; }
   .single-post { margin: 0; padding: 0; background: transparent; border: 0; box-shadow: none; }
   .preview-pagination { display: flex; justify-content: space-between; align-items: center; gap: .75rem; margin-top: .25rem; }
-  .preview-pagination-link { color: var(--muted-color); text-decoration: none; font-size: .92rem; opacity: .72; transition: opacity .15s ease-in-out; }
+  .preview-pagination-link { color: var(--pico-muted-color, var(--muted-color)); text-decoration: none; font-size: .92rem; opacity: .72; transition: opacity .15s ease-in-out; }
   .preview-pagination-link:hover,
   .preview-pagination-link:focus-visible { opacity: 1; text-decoration: underline; }
   .preview-pagination .spacer { flex: 1; }

src/main/engine/templates/post-list.liquid

@@ -1,6 +1,6 @@
 <!doctype html>
-<html lang="{{ language }}">
+<html lang="{{ language }}"{% if html_theme_attribute %} {{ html_theme_attribute }}{% endif %}>
-  {% render 'partials/head', page_title: page_title %}
+  {% render 'partials/head', page_title: page_title, pico_stylesheet_href: pico_stylesheet_href %}
   <body>
     <main>
       {% if archive_context %}

src/main/engine/templates/single-post.liquid

@@ -1,6 +1,6 @@
 <!doctype html>
-<html lang="{{ language }}">
+<html lang="{{ language }}"{% if html_theme_attribute %} {{ html_theme_attribute }}{% endif %}>
-  {% render 'partials/head', page_title: page_title %}
+  {% render 'partials/head', page_title: page_title, pico_stylesheet_href: pico_stylesheet_href %}
   <body>
     <main>
       <article class="single-post" data-template="single-post">

src/main/ipc/handlers.ts

@@ -863,7 +863,7 @@ export function registerIpcHandlers(): void {
     return engine.getProjectMetadata();
   });
 
-  safeHandle('meta:updateProjectMetadata', async (_, updates: { name?: string; description?: string; dataPath?: string; publicUrl?: string; mainLanguage?: string; defaultAuthor?: string; maxPostsPerPage?: number }) => {
+  safeHandle('meta:updateProjectMetadata', async (_, updates: { name?: string; description?: string; dataPath?: string; publicUrl?: string; mainLanguage?: string; defaultAuthor?: string; maxPostsPerPage?: number; picoTheme?: import('../shared/picoThemes').PicoThemeName }) => {
     const engine = getMetaEngine();
     await engine.updateProjectMetadata(updates);
     return engine.getProjectMetadata();

src/main/preload.ts

@@ -158,7 +158,7 @@ export const electronAPI: ElectronAPI = {
     syncOnStartup: () => ipcRenderer.invoke('meta:syncOnStartup'),
     getProjectMetadata: () => ipcRenderer.invoke('meta:getProjectMetadata'),
     setProjectMetadata: (metadata: { name: string; description?: string }) => ipcRenderer.invoke('meta:setProjectMetadata', metadata),
-    updateProjectMetadata: (updates: { name?: string; description?: string; dataPath?: string; mainLanguage?: string; defaultAuthor?: string; maxPostsPerPage?: number }) => ipcRenderer.invoke('meta:updateProjectMetadata', updates),
+    updateProjectMetadata: (updates: { name?: string; description?: string; dataPath?: string; mainLanguage?: string; defaultAuthor?: string; maxPostsPerPage?: number; picoTheme?: import('./shared/picoThemes').PicoThemeName }) => ipcRenderer.invoke('meta:updateProjectMetadata', updates),
   },
 
   // Tag Management (advanced tag operations)

src/main/shared/electronApi.ts

@@ -42,6 +42,7 @@ export interface ProjectMetadata {
   mainLanguage?: string;
   defaultAuthor?: string;
   maxPostsPerPage?: number;
+  picoTheme?: import('./picoThemes').PicoThemeName;
 }
 
 export interface ProjectData {
@@ -528,7 +529,7 @@ export interface ElectronAPI {
     syncOnStartup: () => Promise<{ tags: string[]; categories: string[]; projectMetadata: ProjectMetadata | null }>;
     getProjectMetadata: () => Promise<ProjectMetadata | null>;
     setProjectMetadata: (metadata: { name: string; description?: string }) => Promise<ProjectMetadata | null>;
-    updateProjectMetadata: (updates: { name?: string; description?: string; dataPath?: string; publicUrl?: string; mainLanguage?: string; defaultAuthor?: string; maxPostsPerPage?: number }) => Promise<ProjectMetadata | null>;
+    updateProjectMetadata: (updates: { name?: string; description?: string; dataPath?: string; publicUrl?: string; mainLanguage?: string; defaultAuthor?: string; maxPostsPerPage?: number; picoTheme?: import('./picoThemes').PicoThemeName }) => Promise<ProjectMetadata | null>;
   };
   tags: {
     getAll: () => Promise<TagData[]>;

src/main/shared/picoThemes.ts

@@ -0,0 +1,50 @@
+export const PICO_THEME_NAMES = [
+  'amber',
+  'blue',
+  'cyan',
+  'fuchsia',
+  'green',
+  'grey',
+  'indigo',
+  'jade',
+  'lime',
+  'orange',
+  'pink',
+  'pumpkin',
+  'purple',
+  'red',
+  'sand',
+  'slate',
+  'violet',
+  'yellow',
+  'zinc',
+] as const;
+
+export type PicoThemeName = (typeof PICO_THEME_NAMES)[number];
+export type PicoThemeMode = 'auto' | 'light' | 'dark';
+
+export function isPicoThemeName(value: unknown): value is PicoThemeName {
+  return typeof value === 'string' && (PICO_THEME_NAMES as readonly string[]).includes(value);
+}
+
+export function sanitizePicoTheme(value: unknown): PicoThemeName | undefined {
+  return isPicoThemeName(value) ? value : undefined;
+}
+
+export function sanitizePicoThemeMode(value: unknown): PicoThemeMode | undefined {
+  if (value === 'auto' || value === 'light' || value === 'dark') {
+    return value;
+  }
+  return undefined;
+}
+
+export function getPicoStylesheetAssetName(theme: PicoThemeName | undefined): string {
+  if (!theme) {
+    return 'pico.min.css';
+  }
+  return `pico.${theme}.min.css`;
+}
+
+export function getPicoStylesheetHref(theme: PicoThemeName | undefined): string {
+  return `/assets/${getPicoStylesheetAssetName(theme)}`;
+}

src/renderer/App.tsx

@@ -2,6 +2,7 @@ import React, { useEffect } from 'react';
 import { ActivityBar, Sidebar, Editor, StatusBar, Panel, TabBar, ToastContainer, showToast, ResizablePanel, WindowTitleBar } from './components';
 import { useAppStore, PostData, MediaData, TaskProgress } from './store';
 import { loadTabsForProject, saveTabsForProject } from './utils';
+import { ensureRendererPicoThemeStylesheet, getRendererPicoTheme } from './utils/picoTheme';
 import './App.css';
 
 const App: React.FC = () => {
@@ -22,6 +23,7 @@ const App: React.FC = () => {
     setActiveView,
     setSelectedPost,
     setActiveProject,
+    setPicoTheme,
     openTab,
     restoreTabState,
   } = useAppStore();
@@ -35,6 +37,11 @@ const App: React.FC = () => {
         const activeProject = await window.electronAPI?.projects.getActive();
         if (activeProject) {
           setActiveProject(activeProject as import('./store').ProjectData);
+
+          const metadata = await window.electronAPI?.meta.getProjectMetadata();
+          setPicoTheme(metadata?.picoTheme);
+          const resolvedTheme = getRendererPicoTheme(metadata?.picoTheme);
+          await ensureRendererPicoThemeStylesheet(resolvedTheme);
         }
         
         // Load posts (now with correct project context, limited to 500)

src/renderer/components/DocumentationView/DocumentationView.tsx

@@ -1,10 +1,20 @@
-import React from 'react';
+import React, { useEffect } from 'react';
 import Markdown from 'marked-react';
 import documentationContent from '../../../../DOCUMENTATION.md?raw';
-import '@picocss/pico/css/pico.conditional.slate.min.css';
+import { useAppStore } from '../../store';
+import { ensureRendererPicoThemeStylesheet, getRendererPicoTheme } from '../../utils/picoTheme';
 import './DocumentationView.css';
 
 export const DocumentationView: React.FC = () => {
+  const { picoTheme } = useAppStore();
+  const resolvedTheme = getRendererPicoTheme(picoTheme);
+
+  useEffect(() => {
+    ensureRendererPicoThemeStylesheet(resolvedTheme).catch((error) => {
+      console.error('Failed to load documentation theme stylesheet:', error);
+    });
+  }, [resolvedTheme]);
+
   return (
     <div className="documentation-view">
       <div className="documentation-header">
@@ -12,7 +22,7 @@ export const DocumentationView: React.FC = () => {
         <p>User guide for this installed bDS version.</p>
       </div>
       <main className="documentation-scroll">
-        <div className="documentation-content markdown-body pico" data-theme="auto">
+        <div className="documentation-content markdown-body pico" data-theme="auto" data-pico-theme={resolvedTheme}>
           <article className="documentation-article">
             <Markdown>{documentationContent}</Markdown>
           </article>

src/renderer/components/Editor/Editor.tsx

@@ -9,6 +9,7 @@ import { LinkedMediaPanel } from '../LinkedMediaPanel';
 import { ErrorModal } from '../ErrorModal';
 import { ConfirmDeleteModal } from '../ConfirmDeleteModal';
 import { SettingsView } from '../SettingsView';
+import { StyleView } from '../StyleView/StyleView';
 import { TagsView } from '../TagsView';
 import { TagInput } from '../TagInput';
 import { ChatPanel } from '../ChatPanel';
@@ -1697,6 +1698,7 @@ export const Editor: React.FC = () => {
   const showPost = activeTab?.type === 'post';
   const showMedia = activeTab?.type === 'media';
   const showSettings = activeTab?.type === 'settings';
+  const showStyle = activeTab?.type === 'style';
   const showTags = activeTab?.type === 'tags';
   const showChat = activeTab?.type === 'chat';
   const showImport = activeTab?.type === 'import';
@@ -1765,6 +1767,16 @@ export const Editor: React.FC = () => {
     );
   }
 
+  if (showStyle) {
+    return (
+      <div className="editor">
+        <StyleView />
+        {renderErrorModal()}
+        {renderConfirmDeleteModal()}
+      </div>
+    );
+  }
+
   // Show tags if tags tab is active
   if (showTags) {
     return (

src/renderer/components/Sidebar/Sidebar.tsx

@@ -1244,6 +1244,7 @@ const SettingsNav: React.FC = () => {
 
   // Check if settings panel is currently active
   const isSettingsTabActive = tabs.some(t => t.type === 'settings' && t.id === activeTabId);
+  const isStyleTabActive = tabs.some(t => t.type === 'style' && t.id === activeTabId);
 
   const handleNavClick = (category: SettingsCategory) => {
     // If settings panel is not open or not active, open it first
@@ -1257,6 +1258,10 @@ const SettingsNav: React.FC = () => {
     }, isSettingsTabActive ? 0 : 100);
   };
 
+  const handleStyleClick = () => {
+    openTab({ type: 'style', id: 'style', isTransient: false });
+  };
+
   return (
     <div className="sidebar-content settings-panel">
       <div className="sidebar-section">
@@ -1308,6 +1313,13 @@ const SettingsNav: React.FC = () => {
           <span className="settings-nav-entry-icon">🗄️</span>
           <span>Data</span>
         </button>
+        <button
+          className={`settings-nav-entry ${isStyleTabActive ? 'active' : ''}`}
+          onClick={handleStyleClick}
+        >
+          <span className="settings-nav-entry-icon">🎨</span>
+          <span>Style</span>
+        </button>
       </div>
     </div>
   );

src/renderer/components/StatusBar/StatusBar.css

@@ -89,3 +89,8 @@
   font-weight: 600;
   letter-spacing: 0.5px;
 }
+
+.status-bar-item.theme-badge {
+  border: 1px solid var(--vscode-statusBar-border, transparent);
+  border-radius: 3px;
+}

src/renderer/components/StatusBar/StatusBar.tsx

@@ -1,6 +1,7 @@
 import React, { useState, useEffect } from 'react';
 import { useAppStore } from '../../store';
 import { ProjectSelector } from '../ProjectSelector';
+import { getRendererPicoTheme } from '../../utils/picoTheme';
 import './StatusBar.css';
 
 export const StatusBar: React.FC = () => {
@@ -9,6 +10,7 @@ export const StatusBar: React.FC = () => {
     tasks,
     selectedPostId,
     totalPosts,
+    picoTheme,
   } = useAppStore();
 
   const [selectedPostStatus, setSelectedPostStatus] = useState<string | null>(null);
@@ -25,6 +27,7 @@ export const StatusBar: React.FC = () => {
   }, [selectedPostId]);
 
   const runningTasks = tasks.filter(t => t.status === 'running');
+  const activeTheme = getRendererPicoTheme(picoTheme);
 
   return (
     <div className="status-bar">
@@ -61,6 +64,10 @@ export const StatusBar: React.FC = () => {
           <span>{media.length} media</span>
         </div>
 
+        <div className="status-bar-item theme-badge">
+          <span>Theme: {activeTheme}</span>
+        </div>
+
         {/* App Name */}
         <div className="status-bar-item brand">
           <span>bDS</span>

src/renderer/components/StyleView/StyleView.css

@@ -0,0 +1,106 @@
+.style-view {
+  display: flex;
+  flex-direction: column;
+  height: 100%;
+  padding: 16px;
+  gap: 12px;
+  background: var(--vscode-editor-background);
+  color: var(--vscode-editor-foreground);
+}
+
+.style-view-header h2 {
+  margin: 0;
+  font-size: 20px;
+  font-weight: 600;
+}
+
+.style-view-header p {
+  margin: 6px 0 0;
+  color: var(--vscode-descriptionForeground);
+}
+
+.style-theme-picker {
+  display: grid;
+  grid-template-columns: repeat(auto-fill, minmax(130px, 1fr));
+  gap: 8px;
+}
+
+.style-theme-option {
+  border: 1px solid var(--vscode-input-border);
+  border-radius: 6px;
+  padding: 4px;
+  background: transparent;
+  cursor: pointer;
+}
+
+.style-theme-option.selected {
+  border-color: var(--vscode-focusBorder);
+  box-shadow: 0 0 0 1px var(--vscode-focusBorder);
+}
+
+.style-theme-swatch {
+  display: grid;
+  grid-template-columns: 1fr;
+  gap: 6px;
+  height: 56px;
+  border-radius: 4px;
+  color: var(--vscode-editor-foreground);
+  font-size: 12px;
+  font-weight: 600;
+  letter-spacing: 0.02em;
+  text-transform: capitalize;
+}
+
+.style-theme-tones {
+  display: grid;
+  grid-template-columns: 1.2fr 1fr 1fr;
+  gap: 4px;
+}
+
+.style-theme-tone {
+  height: 24px;
+  border-radius: 3px;
+  border: 1px solid color-mix(in srgb, var(--vscode-input-border) 70%, transparent);
+}
+
+.style-theme-tone-dark {
+  border-color: color-mix(in srgb, #ffffff 18%, transparent);
+}
+
+.style-theme-name {
+  line-height: 1;
+}
+
+.style-apply-row {
+  display: flex;
+  justify-content: flex-start;
+  align-items: flex-end;
+  gap: 12px;
+}
+
+.style-preview-mode-control {
+  display: flex;
+  flex-direction: column;
+  gap: 4px;
+  font-size: 12px;
+  color: var(--vscode-descriptionForeground);
+}
+
+.style-preview-mode-control select {
+  min-width: 130px;
+}
+
+.style-preview-container {
+  flex: 1;
+  min-height: 0;
+  border: 1px solid var(--vscode-input-border);
+  border-radius: 8px;
+  overflow: hidden;
+  background: var(--vscode-editor-background);
+}
+
+.style-preview-frame {
+  width: 100%;
+  height: 100%;
+  border: 0;
+}

src/renderer/components/StyleView/StyleView.tsx

@@ -0,0 +1,138 @@
+import React, { useEffect, useMemo, useState } from 'react';
+import { useAppStore } from '../../store';
+import { showToast } from '../Toast';
+import { PICO_THEME_NAMES, PICO_THEME_PREVIEW_TOKENS, getRendererPicoTheme, ensureRendererPicoThemeStylesheet, type PicoThemeName } from '../../utils/picoTheme';
+import './StyleView.css';
+
+const PREVIEW_SERVER_BASE_URL = 'http://127.0.0.1:4123';
+type PreviewMode = 'auto' | 'light' | 'dark';
+
+function toDisplayName(theme: PicoThemeName): string {
+  return `${theme.charAt(0).toUpperCase()}${theme.slice(1)}`;
+}
+
+export const StyleView: React.FC = () => {
+  const { activeProject, picoTheme, setPicoTheme } = useAppStore();
+  const [selectedTheme, setSelectedTheme] = useState<PicoThemeName>(getRendererPicoTheme(picoTheme));
+  const [previewMode, setPreviewMode] = useState<PreviewMode>('auto');
+  const [isApplying, setIsApplying] = useState(false);
+
+  useEffect(() => {
+    setSelectedTheme(getRendererPicoTheme(picoTheme));
+  }, [picoTheme]);
+
+  useEffect(() => {
+    ensureRendererPicoThemeStylesheet(selectedTheme).catch((error) => {
+      console.error('Failed to load selected renderer theme stylesheet:', error);
+    });
+  }, [selectedTheme]);
+
+  useEffect(() => {
+    const loadTheme = async () => {
+      try {
+        const metadata = await window.electronAPI?.meta.getProjectMetadata();
+        const nextTheme = getRendererPicoTheme(metadata?.picoTheme);
+        setPicoTheme(metadata?.picoTheme);
+        setSelectedTheme(nextTheme);
+      } catch (error) {
+        console.error('Failed to load project style settings:', error);
+      }
+    };
+
+    loadTheme();
+  }, [activeProject?.id, setPicoTheme]);
+
+  const previewUrl = useMemo(() => {
+    return `${PREVIEW_SERVER_BASE_URL}/__style-preview?theme=${encodeURIComponent(selectedTheme)}&mode=${encodeURIComponent(previewMode)}`;
+  }, [selectedTheme, previewMode]);
+
+  const handleApplyTheme = async () => {
+    try {
+      setIsApplying(true);
+      await window.electronAPI?.meta.updateProjectMetadata({ picoTheme: selectedTheme });
+      setPicoTheme(selectedTheme);
+      showToast.success(`Applied theme: ${toDisplayName(selectedTheme)}`);
+    } catch (error) {
+      console.error('Failed to apply style theme:', error);
+      showToast.error('Failed to apply theme');
+    } finally {
+      setIsApplying(false);
+    }
+  };
+
+  return (
+    <div className="style-view">
+      <div className="style-view-header">
+        <h2>Style</h2>
+        <p>Select a Pico CSS theme and preview the top posts before applying.</p>
+      </div>
+
+      <div className="style-theme-picker" role="group" aria-label="Pico Theme Picker">
+        {PICO_THEME_NAMES.map((theme) => {
+          const isSelected = selectedTheme === theme;
+          const preview = PICO_THEME_PREVIEW_TOKENS[theme];
+          return (
+            <button
+              key={theme}
+              type="button"
+              className={`style-theme-option ${isSelected ? 'selected' : ''}`}
+              onClick={() => setSelectedTheme(theme)}
+              aria-pressed={isSelected}
+              aria-label={toDisplayName(theme)}
+            >
+              <span className={`style-theme-swatch style-theme-swatch-${theme}`}>
+                <span className="style-theme-tones" aria-hidden="true">
+                  <span
+                    className="style-theme-tone style-theme-tone-accent"
+                    style={{ background: `linear-gradient(135deg, ${preview.lightPrimary}, ${preview.darkPrimary})` }}
+                  />
+                  <span
+                    className="style-theme-tone style-theme-tone-light"
+                    style={{ backgroundColor: preview.lightBackground }}
+                  />
+                  <span
+                    className="style-theme-tone style-theme-tone-dark"
+                    style={{ backgroundColor: preview.darkBackground }}
+                  />
+                </span>
+                <span className="style-theme-name">{toDisplayName(theme)}</span>
+              </span>
+            </button>
+          );
+        })}
+      </div>
+
+      <div className="style-apply-row">
+        <label className="style-preview-mode-control">
+          <span>Preview mode</span>
+          <select
+            aria-label="Preview mode"
+            value={previewMode}
+            onChange={(event) => setPreviewMode(event.target.value as PreviewMode)}
+          >
+            <option value="auto">Auto</option>
+            <option value="light">Light</option>
+            <option value="dark">Dark</option>
+          </select>
+        </label>
+        <button
+          className="primary"
+          onClick={handleApplyTheme}
+          disabled={isApplying || picoTheme === selectedTheme}
+        >
+          Apply Theme
+        </button>
+      </div>
+
+      <div className="style-preview-container">
+        <iframe
+          title="Theme preview"
+          className="style-preview-frame"
+          src={previewUrl}
+        />
+      </div>
+    </div>
+  );
+};
+
+export default StyleView;

src/renderer/components/StyleView/index.ts

@@ -0,0 +1 @@
+export { StyleView } from './StyleView';

src/renderer/components/TabBar/TabBar.tsx

@@ -41,6 +41,10 @@ const getTabTitle = (
   if (tab.type === 'settings') {
     return 'Settings';
   }
+
+  if (tab.type === 'style') {
+    return 'Style';
+  }
   
   if (tab.type === 'tags') {
     return 'Tags';
@@ -107,6 +111,12 @@ const getTabIcon = (tab: Tab): React.ReactNode => {
           <path d="M9.1 4.4L8.6 2H7.4l-.5 2.4-.7.3-2-1.3-.9.8 1.3 2-.2.7-2.4.5v1.2l2.4.5.3.8-1.3 2 .8.8 2-1.3.8.3.4 2.3h1.2l.5-2.4.8-.3 2 1.3.8-.8-1.3-2 .3-.8 2.3-.4V7.4l-2.4-.5-.3-.8 1.3-2-.8-.8-2 1.3-.7-.2zM9.4 1l.5 2.4L12 2.1l2 2-1.4 2.1 2.4.4v3l-2.4.5L14 12l-2 2-2.1-1.4-.5 2.4h-3L5.9 12.5 4 14l-2-2 1.4-2.1L1 9.4v-3l2.4-.5L2 4l2-2 2.1 1.4.4-2.4h3zm.6 7c0 1.1-.9 2-2 2s-2-.9-2-2 .9-2 2-2 2 .9 2 2zM8 9c.6 0 1-.4 1-1s-.4-1-1-1-1 .4-1 1 .4 1 1 1z"/>
         </svg>
       );
+    case 'style':
+      return (
+        <svg width="16" height="16" viewBox="0 0 16 16" fill="currentColor">
+          <path d="M8 1a7 7 0 1 0 0 14A7 7 0 0 0 8 1zm0 1a6 6 0 0 1 4.91 2.55c-.61.3-1.39.52-2.28.52-1.08 0-1.9-.22-2.62-.42-.71-.2-1.33-.37-2.06-.37-.97 0-1.84.25-2.55.6A6 6 0 0 1 8 2zm-5 6a5.97 5.97 0 0 1 .17-1.42c.59-.37 1.5-.8 2.77-.8.59 0 1.1.14 1.76.32.79.22 1.69.47 2.92.47 1.05 0 1.99-.24 2.75-.59A6 6 0 0 1 13.99 8H3zm10.82 1h-10.6a6 6 0 0 0 10.6 0z"/>
+        </svg>
+      );
     case 'tags':
       return (
         <svg width="16" height="16" viewBox="0 0 16 16" fill="currentColor">

src/renderer/components/index.ts

@@ -12,6 +12,7 @@ export { TaskPopup } from './TaskPopup';
 export { ResizablePanel } from './ResizablePanel';
 export { CredentialsPanel } from './CredentialsPanel';
 export { SettingsView } from './SettingsView';
+export { StyleView } from './StyleView';
 export { TagsView, scrollToTagsSection, type TagsCategory } from './TagsView';
 export { TagInput } from './TagInput';
 export { PostLinks } from './PostLinks';

src/renderer/store/appStore.ts

@@ -12,7 +12,7 @@ import type {
 const STORAGE_KEY = 'bds-app-state';
 
 // Tab types
-export type TabType = 'post' | 'media' | 'settings' | 'tags' | 'chat' | 'import' | 'metadata-diff' | 'git-diff' | 'documentation';
+export type TabType = 'post' | 'media' | 'settings' | 'style' | 'tags' | 'chat' | 'import' | 'metadata-diff' | 'git-diff' | 'documentation';
 
 export interface Tab {
   type: TabType;
@@ -65,6 +65,7 @@ interface AppState {
   selectedPostId: string | null;
   selectedMediaId: string | null;
   preferredEditorMode: EditorMode;
+  picoTheme: import('../../main/shared/picoThemes').PicoThemeName | undefined;
   gitDiffPreferences: GitDiffPreferences;
   
   // Data
@@ -113,6 +114,7 @@ interface AppState {
   setSelectedPost: (id: string | null) => void;
   setSelectedMedia: (id: string | null) => void;
   setPreferredEditorMode: (mode: EditorMode) => void;
+  setPicoTheme: (theme: import('../../main/shared/picoThemes').PicoThemeName | undefined) => void;
   setGitDiffPreferences: (preferences: GitDiffPreferences) => void;
   
   setPosts: (posts: PostData[], hasMore?: boolean, total?: number) => void;
@@ -166,6 +168,7 @@ export const useAppStore = create<AppState>()(
       selectedPostId: null,
       selectedMediaId: null,
       preferredEditorMode: 'wysiwyg',
+      picoTheme: undefined,
       gitDiffPreferences: {
         wordWrap: true,
         viewStyle: 'inline',
@@ -289,6 +292,7 @@ export const useAppStore = create<AppState>()(
       setSelectedPost: (id) => set({ selectedPostId: id }),
       setSelectedMedia: (id) => set({ selectedMediaId: id }),
       setPreferredEditorMode: (mode) => set({ preferredEditorMode: mode }),
+      setPicoTheme: (theme) => set({ picoTheme: theme }),
       setGitDiffPreferences: (preferences) => set({ gitDiffPreferences: preferences }),
       
       // Post Actions
@@ -376,6 +380,7 @@ export const useAppStore = create<AppState>()(
         selectedPostId: state.selectedPostId,
         selectedMediaId: state.selectedMediaId,
         preferredEditorMode: state.preferredEditorMode,
+        picoTheme: state.picoTheme,
         gitDiffPreferences: state.gitDiffPreferences,
         // Tabs are persisted here for now (project-specific persistence handled separately)
         tabs: state.tabs,
@@ -393,6 +398,7 @@ export const useAppStore = create<AppState>()(
           activeTabId: persistedState.activeTabId || null,
           panelActiveTab: persistedState.panelActiveTab || current.panelActiveTab,
           dirtyPosts: new Set(persistedState.dirtyPosts || []),
+          picoTheme: persistedState.picoTheme || current.picoTheme,
           gitDiffPreferences: persistedState.gitDiffPreferences || current.gitDiffPreferences,
         };
       },

src/renderer/utils/picoTheme.ts

@@ -0,0 +1,70 @@
+import { PICO_THEME_NAMES, sanitizePicoTheme, type PicoThemeName } from '../../main/shared/picoThemes';
+
+export { PICO_THEME_NAMES, type PicoThemeName };
+
+export interface PicoThemePreviewToken {
+  lightBackground: string;
+  darkBackground: string;
+  lightPrimary: string;
+  darkPrimary: string;
+}
+
+export const PICO_THEME_PREVIEW_TOKENS: Record<PicoThemeName, PicoThemePreviewToken> = {
+  amber: { lightBackground: '#fff', darkBackground: 'rgb(19, 22.5, 30.5)', lightPrimary: '#876400', darkPrimary: '#c79400' },
+  blue: { lightBackground: '#fff', darkBackground: 'rgb(19, 22.5, 30.5)', lightPrimary: '#2060df', darkPrimary: '#8999f9' },
+  cyan: { lightBackground: '#fff', darkBackground: 'rgb(19, 22.5, 30.5)', lightPrimary: '#047878', darkPrimary: '#0ab1b1' },
+  fuchsia: { lightBackground: '#fff', darkBackground: 'rgb(19, 22.5, 30.5)', lightPrimary: '#c1208b', darkPrimary: '#f869bf' },
+  green: { lightBackground: '#fff', darkBackground: 'rgb(19, 22.5, 30.5)', lightPrimary: '#33790f', darkPrimary: '#4eb31b' },
+  grey: { lightBackground: '#fff', darkBackground: 'rgb(19, 22.5, 30.5)', lightPrimary: '#6a6a6a', darkPrimary: '#9e9e9e' },
+  indigo: { lightBackground: '#fff', darkBackground: 'rgb(19, 22.5, 30.5)', lightPrimary: '#655cd6', darkPrimary: '#a294e5' },
+  jade: { lightBackground: '#fff', darkBackground: 'rgb(19, 22.5, 30.5)', lightPrimary: '#007a50', darkPrimary: '#00b478' },
+  lime: { lightBackground: '#fff', darkBackground: 'rgb(19, 22.5, 30.5)', lightPrimary: '#577400', darkPrimary: '#82ab00' },
+  orange: { lightBackground: '#fff', darkBackground: 'rgb(19, 22.5, 30.5)', lightPrimary: '#bd3c13', darkPrimary: '#f56b3d' },
+  pink: { lightBackground: '#fff', darkBackground: 'rgb(19, 22.5, 30.5)', lightPrimary: '#c72259', darkPrimary: '#f7708e' },
+  pumpkin: { lightBackground: '#fff', darkBackground: 'rgb(19, 22.5, 30.5)', lightPrimary: '#9c5900', darkPrimary: '#e48500' },
+  purple: { lightBackground: '#fff', darkBackground: 'rgb(19, 22.5, 30.5)', lightPrimary: '#aa40bf', darkPrimary: '#d47de4' },
+  red: { lightBackground: '#fff', darkBackground: 'rgb(19, 22.5, 30.5)', lightPrimary: '#c52f21', darkPrimary: '#f17961' },
+  sand: { lightBackground: '#fff', darkBackground: 'rgb(19, 22.5, 30.5)', lightPrimary: '#6e6a60', darkPrimary: '#a39e8f' },
+  slate: { lightBackground: '#fff', darkBackground: 'rgb(19, 22.5, 30.5)', lightPrimary: '#5d6b89', darkPrimary: '#909ebe' },
+  violet: { lightBackground: '#fff', darkBackground: 'rgb(19, 22.5, 30.5)', lightPrimary: '#8352c5', darkPrimary: '#b290d9' },
+  yellow: { lightBackground: '#fff', darkBackground: 'rgb(19, 22.5, 30.5)', lightPrimary: '#756b00', darkPrimary: '#ad9f00' },
+  zinc: { lightBackground: '#fff', darkBackground: 'rgb(19, 22.5, 30.5)', lightPrimary: '#646b79', darkPrimary: '#969eaf' },
+};
+
+const themeStylesheetLoaders: Record<PicoThemeName, () => Promise<unknown>> = {
+  amber: () => import('@picocss/pico/css/pico.conditional.amber.min.css'),
+  blue: () => import('@picocss/pico/css/pico.conditional.blue.min.css'),
+  cyan: () => import('@picocss/pico/css/pico.conditional.cyan.min.css'),
+  fuchsia: () => import('@picocss/pico/css/pico.conditional.fuchsia.min.css'),
+  green: () => import('@picocss/pico/css/pico.conditional.green.min.css'),
+  grey: () => import('@picocss/pico/css/pico.conditional.grey.min.css'),
+  indigo: () => import('@picocss/pico/css/pico.conditional.indigo.min.css'),
+  jade: () => import('@picocss/pico/css/pico.conditional.jade.min.css'),
+  lime: () => import('@picocss/pico/css/pico.conditional.lime.min.css'),
+  orange: () => import('@picocss/pico/css/pico.conditional.orange.min.css'),
+  pink: () => import('@picocss/pico/css/pico.conditional.pink.min.css'),
+  pumpkin: () => import('@picocss/pico/css/pico.conditional.pumpkin.min.css'),
+  purple: () => import('@picocss/pico/css/pico.conditional.purple.min.css'),
+  red: () => import('@picocss/pico/css/pico.conditional.red.min.css'),
+  sand: () => import('@picocss/pico/css/pico.conditional.sand.min.css'),
+  slate: () => import('@picocss/pico/css/pico.conditional.slate.min.css'),
+  violet: () => import('@picocss/pico/css/pico.conditional.violet.min.css'),
+  yellow: () => import('@picocss/pico/css/pico.conditional.yellow.min.css'),
+  zinc: () => import('@picocss/pico/css/pico.conditional.zinc.min.css'),
+};
+
+const loadedThemes = new Set<PicoThemeName>();
+
+export function getRendererPicoTheme(theme: unknown): PicoThemeName {
+  return sanitizePicoTheme(theme) ?? 'slate';
+}
+
+export async function ensureRendererPicoThemeStylesheet(theme: PicoThemeName): Promise<void> {
+  if (loadedThemes.has(theme)) {
+    return;
+  }
+
+  const loader = themeStylesheetLoaders[theme];
+  await loader();
+  loadedThemes.add(theme);
+}

tests/engine/MetaEngine.test.ts

@@ -580,6 +580,33 @@ describe('MetaEngine', () => {
       expect(metadata?.defaultAuthor).toBe('Loaded Author');
     });
 
+    it('should persist picoTheme to filesystem', async () => {
+      await metaEngine.setProjectMetadata({
+        name: 'Styled Project',
+        picoTheme: 'slate',
+      } as any);
+
+      const metaDir = metaEngine.getMetaDir();
+      const projectPath = normalizePath(`${metaDir}/project.json`);
+      const content = mockFiles.get(projectPath);
+      const parsed = JSON.parse(content!);
+      expect(parsed.picoTheme).toBe('slate');
+    });
+
+    it('should load picoTheme from filesystem', async () => {
+      const metaDir = metaEngine.getMetaDir();
+      const projectPath = normalizePath(`${metaDir}/project.json`);
+      mockFiles.set(projectPath, JSON.stringify({
+        name: 'Loaded Project',
+        picoTheme: 'zinc',
+      }));
+
+      await metaEngine.loadProjectMetadata();
+
+      const metadata = await metaEngine.getProjectMetadata();
+      expect((metadata as any)?.picoTheme).toBe('zinc');
+    });
+
     it('should set and get maxPostsPerPage in project metadata', async () => {
       await metaEngine.setProjectMetadata({
         name: 'My Blog',

tests/engine/PreviewServer.test.ts

@@ -196,6 +196,60 @@ describe('PreviewServer', () => {
     expect(lightboxLoadingImageResponse.headers.get('content-type')).toContain('image/gif');
   });
 
+  it('uses selected pico theme stylesheet from project metadata', async () => {
+    server = new PreviewServer({
+      postEngine: makeEngine([makePost()]),
+      settingsEngine: {
+        setProjectContext: vi.fn(),
+        async getProjectMetadata() {
+          return {
+            maxPostsPerPage: 50,
+            picoTheme: 'slate',
+          };
+        },
+      } as any,
+      getActiveProjectContext: async () => ({ projectId: 'default' }),
+    });
+
+    await server.start(0);
+
+    const rootResponse = await fetch(`${server.getBaseUrl()}/`);
+    expect(rootResponse.status).toBe(200);
+    const rootHtml = await rootResponse.text();
+
+    expect(rootHtml).toContain('href="/assets/pico.slate.min.css"');
+    expect(rootHtml).not.toContain('href="/assets/pico.min.css"');
+
+    const themedCss = await fetch(`${server.getBaseUrl()}/assets/pico.slate.min.css`);
+    expect(themedCss.status).toBe(200);
+    expect(themedCss.headers.get('content-type')).toContain('text/css');
+  });
+
+  it('supports preview mode override for style preview route', async () => {
+    server = new PreviewServer({
+      postEngine: makeEngine([makePost()]),
+      settingsEngine: {
+        setProjectContext: vi.fn(),
+        async getProjectMetadata() {
+          return {
+            maxPostsPerPage: 50,
+            picoTheme: 'slate',
+          };
+        },
+      } as any,
+      getActiveProjectContext: async () => ({ projectId: 'default' }),
+    });
+
+    await server.start(0);
+
+    const response = await fetch(`${server.getBaseUrl()}/__style-preview?theme=slate&mode=dark`);
+    expect(response.status).toBe(200);
+    const html = await response.text();
+
+    expect(html).toContain('<html lang="en" data-theme="dark">');
+    expect(html).toContain('href="/assets/pico.slate.min.css"');
+  });
+
   it('limits list routes to 50 posts', async () => {
     const posts = Array.from({ length: 60 }).map((_, index) =>
       makePost({
@@ -279,7 +333,7 @@ describe('PreviewServer', () => {
     expect(separatorCount).toBe(1);
 
     expect(html).toContain('.archive-day-separator { position: relative; height: 2px;');
-    expect(html).toContain('color: var(--color);');
+    expect(html).toContain('color: var(--pico-color, var(--color));');
     expect(html).toContain('border-top: 1px solid currentColor;');
     expect(html).toContain('opacity: .18;');
     expect(html).toContain('.archive-day-separator::before');

tests/renderer/components/PagesShortcut.test.tsx

@@ -156,4 +156,26 @@ describe('Pages shortcut UI', () => {
     expect(wrappers.length).toBeGreaterThanOrEqual(2);
     expect((wrappers[0] as HTMLElement).style.display).toBe('flex');
   });
+
+  it('opens style tab from settings sidebar navigation', async () => {
+    useAppStore.setState({
+      sidebarVisible: true,
+      tabs: [],
+      activeTabId: null,
+    });
+    useAppStore.getState().setActiveView('settings');
+
+    render(<Sidebar />);
+
+    const styleButton = await screen.findByRole('button', { name: /style/i });
+    styleButton.click();
+
+    const state = useAppStore.getState();
+    expect(state.tabs).toEqual(
+      expect.arrayContaining([
+        expect.objectContaining({ type: 'style', id: 'style' }),
+      ])
+    );
+    expect(state.activeTabId).toBe('style');
+  });
 });

tests/renderer/components/StatusBar.test.tsx

@@ -0,0 +1,28 @@
+import React from 'react';
+import { describe, it, expect, beforeEach, vi } from 'vitest';
+import { render, screen } from '@testing-library/react';
+import { StatusBar } from '../../../src/renderer/components/StatusBar/StatusBar';
+import { useAppStore } from '../../../src/renderer/store';
+
+vi.mock('../../../src/renderer/components/ProjectSelector', () => ({
+  ProjectSelector: () => <div data-testid="project-selector">Project</div>,
+}));
+
+describe('StatusBar', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    useAppStore.setState({
+      media: [],
+      tasks: [],
+      selectedPostId: null,
+      totalPosts: 0,
+      picoTheme: 'slate',
+    } as any);
+  });
+
+  it('shows the currently applied theme', () => {
+    render(<StatusBar />);
+
+    expect(screen.getByText('Theme: slate')).toBeInTheDocument();
+  });
+});

tests/renderer/components/StyleView.test.tsx

@@ -0,0 +1,78 @@
+import React from 'react';
+import { describe, it, expect, beforeEach, vi } from 'vitest';
+import { fireEvent, render, screen } from '@testing-library/react';
+import { StyleView } from '../../../src/renderer/components/StyleView/StyleView';
+import { useAppStore } from '../../../src/renderer/store';
+
+describe('StyleView', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+
+    useAppStore.setState({
+      activeProject: {
+        id: 'project-1',
+        name: 'Test Project',
+        slug: 'test-project',
+        isActive: true,
+        createdAt: new Date().toISOString(),
+        updatedAt: new Date().toISOString(),
+      },
+      picoTheme: 'slate',
+    } as any);
+
+    (window as any).electronAPI = {
+      ...(window as any).electronAPI,
+      meta: {
+        ...(window as any).electronAPI?.meta,
+        getProjectMetadata: vi.fn().mockResolvedValue({ picoTheme: 'slate' }),
+        updateProjectMetadata: vi.fn().mockResolvedValue({ picoTheme: 'blue' }),
+      },
+    };
+  });
+
+  it('lets users select a theme and apply it', async () => {
+    render(<StyleView />);
+
+    const blueButton = await screen.findByRole('button', { name: /blue/i });
+    fireEvent.click(blueButton);
+
+    const applyButton = screen.getByRole('button', { name: /apply theme/i });
+    fireEvent.click(applyButton);
+
+    expect((window as any).electronAPI.meta.updateProjectMetadata).toHaveBeenCalledWith(
+      expect.objectContaining({ picoTheme: 'blue' })
+    );
+  });
+
+  it('renders the style preview iframe for top posts with selected theme', async () => {
+    render(<StyleView />);
+
+    const iframe = await screen.findByTitle('Theme preview');
+    expect(iframe.getAttribute('src')).toContain('/__style-preview');
+    expect(iframe.getAttribute('src')).toContain('theme=slate');
+    expect(iframe.getAttribute('src')).toContain('mode=auto');
+  });
+
+  it('lets users force dark/light mode for preview iframe', async () => {
+    render(<StyleView />);
+
+    const modeSelect = await screen.findByLabelText(/preview mode/i);
+    fireEvent.change(modeSelect, { target: { value: 'dark' } });
+
+    const iframe = await screen.findByTitle('Theme preview');
+    expect(iframe.getAttribute('src')).toContain('mode=dark');
+  });
+
+  it('renders each theme swatch with accent, light, and dark tones', async () => {
+    const { container } = render(<StyleView />);
+
+    await screen.findByRole('button', { name: /blue/i });
+
+    const blueSwatch = container.querySelector('.style-theme-swatch-blue');
+    expect(blueSwatch).not.toBeNull();
+
+    const tones = blueSwatch?.querySelectorAll('.style-theme-tone') ?? [];
+    expect(tones.length).toBe(3);
+    expect(blueSwatch?.textContent).toContain('Blue');
+  });
+});

tests/renderer/components/TabBar.test.tsx

@@ -86,4 +86,15 @@ describe('TabBar', () => {
 
     expect(container.querySelector('.tab-bar')).toBeNull();
   });
+
+  it('renders style tab label', async () => {
+    useAppStore.setState({
+      tabs: [{ type: 'style', id: 'style', isTransient: false }],
+      activeTabId: 'style',
+    });
+
+    render(<TabBar />);
+
+    expect(await screen.findByText('Style')).toBeInTheDocument();
+  });
 });

tests/renderer/documentationStructure.test.ts

@@ -23,7 +23,8 @@ describe('documentation structure and presentation', () => {
     );
     const source = readFileSync(viewPath, 'utf8');
 
-    expect(source).toContain('@picocss/pico/css/pico.conditional.slate.min.css');
+    expect(source).toContain('ensureRendererPicoThemeStylesheet');
+    expect(source).toContain('getRendererPicoTheme');
     expect(source).toContain('className="documentation-content markdown-body pico"');
     expect(source).toContain('data-theme="auto"');
   });

tests/renderer/store/tabStore.test.ts

@@ -343,6 +343,29 @@ describe('Tab Management', () => {
 
       expect(getStore().tabs).toHaveLength(1);
     });
+
+    it('should open style as a dedicated tab', () => {
+      getStore().openTab({ type: 'style', id: 'style', isTransient: false });
+
+      expect(getStore().tabs).toHaveLength(1);
+      expect(getStore().tabs[0].type).toBe('style');
+      expect(getStore().activeTabId).toBe('style');
+    });
+
+    it('should restore style tab from persisted state', () => {
+      const tabState = {
+        tabs: [
+          { type: 'style' as const, id: 'style', isTransient: false },
+        ],
+        activeTabId: 'style',
+      };
+
+      getStore().restoreTabState(tabState);
+
+      expect(getStore().tabs).toHaveLength(1);
+      expect(getStore().tabs[0].type).toBe('style');
+      expect(getStore().activeTabId).toBe('style');
+    });
   });
 
   describe('Multiple Tab Types', () => {