diff --git a/server/db.js b/server/db.js
index 4d49261..ff9b754 100644
--- a/server/db.js
+++ b/server/db.js
@@ -71,6 +71,35 @@ export async function initDb() {
     )
   `)
 
+  await db.query(`
+    CREATE TABLE IF NOT EXISTS themes (
+      id text PRIMARY KEY,
+      tenant_id text NOT NULL,
+      name text NOT NULL,
+      applies_to text NOT NULL DEFAULT 'all' CHECK (applies_to IN ('all', 'report', 'email')),
+      theme jsonb NOT NULL,
+      created_by text,
+      created_at timestamptz NOT NULL DEFAULT now(),
+      updated_at timestamptz NOT NULL DEFAULT now()
+    )
+  `)
+
+  await db.query(`
+    CREATE TABLE IF NOT EXISTS theme_assets (
+      id text PRIMARY KEY,
+      tenant_id text NOT NULL,
+      theme_id text NOT NULL REFERENCES themes(id) ON DELETE CASCADE,
+      asset_key text NOT NULL,
+      filename text NOT NULL,
+      mime_type text NOT NULL,
+      byte_size integer NOT NULL,
+      public_token text NOT NULL UNIQUE,
+      data bytea NOT NULL,
+      created_at timestamptz NOT NULL DEFAULT now(),
+      UNIQUE(theme_id, asset_key)
+    )
+  `)
+
   await db.query(`
     CREATE TABLE IF NOT EXISTS api_keys (
       id text PRIMARY KEY,
@@ -101,4 +130,12 @@ export async function initDb() {
     CREATE INDEX IF NOT EXISTS template_assets_template_idx
     ON template_assets (template_id)
   `)
+  await db.query(`
+    CREATE INDEX IF NOT EXISTS themes_tenant_created_idx
+    ON themes (tenant_id, created_at DESC)
+  `)
+  await db.query(`
+    CREATE INDEX IF NOT EXISTS theme_assets_theme_idx
+    ON theme_assets (theme_id)
+  `)
 }
diff --git a/server/index.js b/server/index.js
index 92664eb..456a527 100644
--- a/server/index.js
+++ b/server/index.js
@@ -5,6 +5,7 @@ import { initDb, getPool } from './db.js'
 import { readSession, registerAuthRoutes, requireAuth, verifyMachineToken } from './auth.js'
 import { renderEmailHtml, renderReportHtml } from './templateEngine.js'
 import { getTemplateAsset, importTemplatePack, templatePackSpec } from './templatePack.js'
+import { getThemeAsset, importThemeJson, importThemePack, themePackSpec } from './themePack.js'
 
 const app = express()
 const port = Number(process.env.PORT || 3000)
@@ -25,6 +26,20 @@ app.get('/api/health/ready', async (_req, res) => {
 
 registerAuthRoutes(app)
 
+app.get('/theme-media/:token/:filename', async (req, res, next) => {
+  try {
+    const asset = await getThemeAsset(req.params.token)
+    if (!asset) return res.status(404).end()
+    res.setHeader('Content-Type', asset.mime_type)
+    res.setHeader('Content-Length', String(asset.byte_size))
+    res.setHeader('Cache-Control', 'public, max-age=31536000, immutable')
+    res.setHeader('X-Content-Type-Options', 'nosniff')
+    res.send(asset.data)
+  } catch (error) {
+    next(error)
+  }
+})
+
 app.get('/media/:token/:filename', async (req, res, next) => {
   try {
     const asset = await getTemplateAsset(req.params.token)
@@ -255,6 +270,60 @@ app.get('/api/template-packs/spec', (_req, res) => {
   res.json(templatePackSpec)
 })
 
+app.get('/api/theme-packs/spec', (_req, res) => {
+  res.setHeader('Cache-Control', 'no-store')
+  res.json(themePackSpec)
+})
+
+app.get('/api/themes', async (_req, res) => {
+  const { rows } = await getPool().query(
+    `SELECT id,name,applies_to,theme,created_at,updated_at
+     FROM themes
+     WHERE tenant_id=$1
+     ORDER BY created_at DESC`,
+    [tenantId]
+  )
+  res.setHeader('Cache-Control', 'no-store')
+  res.json(rows)
+})
+
+app.post('/api/theme-packs/import-json', async (req, res) => {
+  try {
+    const baseUrl = (process.env.APP_BASE_URL || `${req.protocol}://${req.get('host')}`).replace(/\/$/, '')
+    const imported = await importThemeJson(req.body, {
+      tenantId,
+      createdBy: userId(req),
+      baseUrl
+    })
+    res.status(201).json(imported)
+  } catch (error) {
+    res.status(400).json({ error: 'invalid_theme_pack', detail: error instanceof Error ? error.message : String(error) })
+  }
+})
+
+app.post(
+  '/api/theme-packs/import',
+  express.raw({
+    type: ['application/zip', 'application/x-zip-compressed', 'application/octet-stream'],
+    limit: '20mb'
+  }),
+  async (req, res, next) => {
+    try {
+      const baseUrl = (process.env.APP_BASE_URL || `${req.protocol}://${req.get('host')}`).replace(/\/$/, '')
+      const imported = await importThemePack(req.body, {
+        tenantId,
+        createdBy: userId(req),
+        baseUrl
+      })
+      res.status(201).json(imported)
+    } catch (error) {
+      if (error?.type === 'entity.too.large') return res.status(413).json({ error: 'theme_pack_too_large' })
+      if (error instanceof Error) return res.status(400).json({ error: 'invalid_theme_pack', detail: error.message })
+      next(error)
+    }
+  }
+)
+
 app.post(
   '/api/template-packs/import',
   express.raw({
diff --git a/server/themePack.js b/server/themePack.js
new file mode 100644
index 0000000..b61c467
--- /dev/null
+++ b/server/themePack.js
@@ -0,0 +1,215 @@
+import crypto from 'node:crypto'
+import path from 'node:path'
+import AdmZip from 'adm-zip'
+import { getPool } from './db.js'
+
+const MAX_FILES = 60
+const MAX_UNCOMPRESSED_BYTES = 30 * 1024 * 1024
+const MAX_ASSET_BYTES = 10 * 1024 * 1024
+const MAX_MANIFEST_BYTES = 128 * 1024
+
+const MIME_BY_EXT = {
+  '.png': 'image/png',
+  '.jpg': 'image/jpeg',
+  '.jpeg': 'image/jpeg',
+  '.webp': 'image/webp',
+  '.gif': 'image/gif'
+}
+
+function cleanArchivePath(value) {
+  const normalized = String(value || '').replaceAll('\\\\', '/')
+  if (!normalized || normalized.startsWith('/') || normalized.includes('../') || normalized.includes('/..')) {
+    throw new Error('Theme pack contains an unsafe path')
+  }
+  return normalized
+}
+
+function replaceAssetRefs(value, assetUrls) {
+  if (typeof value === 'string') {
+    return value.replace(/asset:\/\/([a-zA-Z0-9._-]+)/g, (full, key) => assetUrls[key] || full)
+  }
+  if (Array.isArray(value)) return value.map(item => replaceAssetRefs(item, assetUrls))
+  if (value && typeof value === 'object') {
+    return Object.fromEntries(
+      Object.entries(value).map(([key, child]) => [key, replaceAssetRefs(child, assetUrls)])
+    )
+  }
+  return value
+}
+
+function validateManifest(manifest) {
+  if (!manifest || manifest.format !== 'template-studio-theme' || manifest.version !== 1) {
+    throw new Error('theme-pack.json must use format "template-studio-theme" version 1')
+  }
+  if (typeof manifest.name !== 'string' || !manifest.name.trim()) {
+    throw new Error('Theme name is required')
+  }
+  if (!manifest.theme || typeof manifest.theme !== 'object' || Array.isArray(manifest.theme)) {
+    throw new Error('Theme object is required')
+  }
+
+  const appliesTo = ['all', 'report', 'email'].includes(manifest.appliesTo) ? manifest.appliesTo : 'all'
+  const assets = Array.isArray(manifest.assets) ? manifest.assets : []
+  const keys = new Set()
+
+  for (const asset of assets) {
+    if (!asset || typeof asset.key !== 'string' || !/^[a-zA-Z0-9._-]{1,80}$/.test(asset.key)) {
+      throw new Error('Each theme asset requires a simple key')
+    }
+    if (keys.has(asset.key)) throw new Error(`Duplicate theme asset key: ${asset.key}`)
+    keys.add(asset.key)
+    cleanArchivePath(asset.file)
+  }
+
+  return {
+    name: manifest.name.trim(),
+    appliesTo,
+    theme: manifest.theme,
+    assets
+  }
+}
+
+async function saveTheme({ name, appliesTo, theme, assets = [], entryMap, tenantId, createdBy, baseUrl }) {
+  const db = await getPool().connect()
+  try {
+    await db.query('BEGIN')
+
+    const themeId = crypto.randomUUID()
+    const assetUrls = {}
+
+    await db.query(
+      `INSERT INTO themes (id,tenant_id,name,applies_to,theme,created_by)
+       VALUES ($1,$2,$3,$4,$5,$6)`,
+      [themeId, tenantId, name, appliesTo, {}, createdBy]
+    )
+
+    for (const asset of assets) {
+      const archivePath = cleanArchivePath(asset.file)
+      const entry = entryMap?.get(archivePath)
+      if (!entry) throw new Error(`Missing theme asset file: ${archivePath}`)
+
+      const extension = path.extname(archivePath).toLowerCase()
+      const mimeType = MIME_BY_EXT[extension]
+      if (!mimeType) throw new Error(`Unsupported theme asset type: ${archivePath}`)
+
+      const data = entry.getData()
+      if (data.length > MAX_ASSET_BYTES) throw new Error(`Theme asset exceeds 10 MB: ${archivePath}`)
+
+      const id = crypto.randomUUID()
+      const publicToken = crypto.randomBytes(24).toString('base64url')
+      const filename = path.basename(archivePath).replace(/[^a-zA-Z0-9._-]/g, '-') || `asset${extension}`
+
+      await db.query(
+        `INSERT INTO theme_assets
+          (id,tenant_id,theme_id,asset_key,filename,mime_type,byte_size,public_token,data)
+         VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9)`,
+        [id, tenantId, themeId, asset.key, filename, mimeType, data.length, publicToken, data]
+      )
+
+      assetUrls[asset.key] = `${baseUrl}/theme-media/${publicToken}/${encodeURIComponent(filename)}`
+    }
+
+    const resolvedTheme = replaceAssetRefs(theme, assetUrls)
+    const unresolved = JSON.stringify(resolvedTheme).match(/asset:\/\/[a-zA-Z0-9._-]+/g)
+    if (unresolved?.length) throw new Error(`Unknown theme asset reference: ${unresolved[0]}`)
+
+    const { rows } = await db.query(
+      `UPDATE themes
+       SET theme=$1,updated_at=now()
+       WHERE id=$2
+       RETURNING id,name,applies_to,theme,created_at,updated_at`,
+      [resolvedTheme, themeId]
+    )
+
+    await db.query('COMMIT')
+    return { theme: rows[0], asset_count: assets.length }
+  } catch (error) {
+    await db.query('ROLLBACK')
+    throw error
+  } finally {
+    db.release()
+  }
+}
+
+export async function importThemePack(buffer, { tenantId, createdBy, baseUrl }) {
+  if (!Buffer.isBuffer(buffer) || !buffer.length) throw new Error('Theme ZIP body is empty')
+
+  const zip = new AdmZip(buffer)
+  const entries = zip.getEntries().filter(entry => !entry.isDirectory)
+  if (!entries.length || entries.length > MAX_FILES) {
+    throw new Error(`Theme pack must contain between 1 and ${MAX_FILES} files`)
+  }
+
+  let totalBytes = 0
+  const entryMap = new Map()
+  for (const entry of entries) {
+    const archivePath = cleanArchivePath(entry.entryName)
+    totalBytes += Number(entry.header?.size || 0)
+    if (totalBytes > MAX_UNCOMPRESSED_BYTES) throw new Error('Theme pack expands beyond the 30 MB limit')
+    entryMap.set(archivePath, entry)
+  }
+
+  const manifestEntry = entryMap.get('theme-pack.json')
+  if (!manifestEntry) throw new Error('Theme pack is missing theme-pack.json')
+  if (Number(manifestEntry.header?.size || 0) > MAX_MANIFEST_BYTES) {
+    throw new Error('theme-pack.json is too large')
+  }
+
+  let manifest
+  try {
+    manifest = JSON.parse(manifestEntry.getData().toString('utf8'))
+  } catch {
+    throw new Error('theme-pack.json is not valid JSON')
+  }
+
+  const validated = validateManifest(manifest)
+  return saveTheme({ ...validated, entryMap, tenantId, createdBy, baseUrl })
+}
+
+export async function importThemeJson(manifest, context) {
+  const validated = validateManifest({ ...manifest, assets: [] })
+  return saveTheme({ ...validated, ...context })
+}
+
+export async function getThemeAsset(publicToken) {
+  const { rows } = await getPool().query(
+    `SELECT filename,mime_type,byte_size,data
+     FROM theme_assets
+     WHERE public_token=$1
+     LIMIT 1`,
+    [publicToken]
+  )
+  return rows[0] || null
+}
+
+export const themePackSpec = {
+  format: 'template-studio-theme',
+  version: 1,
+  name: 'Clean Operations',
+  appliesTo: 'report',
+  theme: {
+    backgroundColor: '#eef3f7',
+    surfaceColor: '#ffffff',
+    textColor: '#172b3a',
+    mutedColor: '#607282',
+    accentColor: '#123b5d',
+    buttonTextColor: '#ffffff',
+    borderColor: '#d8e1e8',
+    borderRadius: 8,
+    fontFamily: 'Arial',
+    reportDensity: 'auto',
+    pageMarginTop: 9,
+    pageMarginRight: 9,
+    pageMarginBottom: 9,
+    pageMarginLeft: 9,
+    pagePadding: 14,
+    pageBackgroundMode: 'none',
+    pageBackgroundImage: 'asset://background',
+    decorativeBorder: false,
+    borderImage: 'asset://border'
+  },
+  assets: [
+    { key: 'background', file: 'assets/background.webp' },
+    { key: 'border', file: 'assets/border.png' }
+  ]
+}