> ## Documentation Index > Fetch the complete documentation index at: https://loops.so/docs/llms.txt > Use this file to discover all available pages before exploring further. # Update a theme > Update a theme's name and/or styles. Style changes cascade to every email using the theme. ## OpenAPI ````yaml https://app.loops.so/openapi.json post /v1/themes/{themeId} openapi: 3.1.0 info: title: Loops OpenAPI Spec description: This is the OpenAPI Spec for the [Loops API](https://loops.so/docs/api). version: 1.21.6 servers: - url: https://app.loops.so/api security: [] tags: - name: API key - name: Audience segments description: View audience segments - name: Campaigns description: Create and manage email campaigns - name: Campaign groups description: Organize campaigns into groups - name: Configuration description: View configuration settings - name: Contacts description: Manage contacts in your audience - name: Contact properties description: Manage contact properties - name: Components description: View email components - name: Email messages description: Manage email message content for campaigns - name: Events description: Trigger workflows with events - name: Event patterns description: View workflow event patterns - name: Mailing lists description: View mailing lists - name: Themes description: View email themes - name: Transactional emails description: Create, manage, and send transactional emails - name: Transactional groups description: Organize transactional emails into groups - name: Uploads description: Upload image assets - name: Workflows description: View and mutate workflow graphs - name: Workflow nodes description: View and mutate workflow nodes - name: Webhooks description: >- Events Loops sends to your configured webhook endpoint when certain events happen in your account. Configure an endpoint in Settings → Webhooks. Each account supports one webhook endpoint. Events are signed with `webhook-id`, `webhook-timestamp`, and `webhook-signature` headers and delivered at a maximum rate of 10 per second. See https://loops.so/docs/webhooks for setup, verification, and payload details. paths: /v1/themes/{themeId}: parameters: - name: themeId in: path required: true description: The ID of the theme. schema: type: string examples: - clt3u5v7w9x1y3z5a7b9c1d3 post: tags: - Themes summary: Update a theme description: >- Update a theme's name and/or styles. When `styles` change, the update cascades to every email using this theme, and `affectedEmailCount` in the response reports how many emails were affected. Manual style edits made on individual emails are preserved: the cascade only changes properties an email has not overridden. A per-email override is removed only when it becomes identical to the theme's new value, after which that email follows the theme for that property. operationId: updateTheme requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/UpdateThemeBody' responses: '200': description: Successful. content: application/json: schema: $ref: '#/components/schemas/UpdateThemeResponse' '400': description: Invalid `themeId` or request body. content: application/json: schema: $ref: '#/components/schemas/ThemeFailureResponse' '401': description: Invalid API key or content API not enabled for this team. '404': description: Theme not found. content: application/json: schema: $ref: '#/components/schemas/ThemeFailureResponse' '405': description: Wrong HTTP request method. security: - apiKey: [] components: schemas: UpdateThemeBody: type: object description: At least one of `name` or `styles` must be provided. properties: name: type: string styles: $ref: '#/components/schemas/ThemeStyles' UpdateThemeResponse: allOf: - $ref: '#/components/schemas/ThemeResponse' - type: object properties: affectedEmailCount: type: number description: >- The number of emails using this theme that are affected by the style change. `0` when only the name changed. required: - affectedEmailCount examples: - id: clt3u5v7w9x1y3z5a7b9c1d3 name: Default styles: backgroundColor: '#f5f5f5' backgroundXPadding: 24 backgroundYPadding: 24 bodyColor: '#ffffff' bodyXPadding: 24 bodyYPadding: 24 bodyFontFamily: Helvetica bodyFontCategory: sans-serif borderColor: '#e5e5e5' borderWidth: 1 borderRadius: 8 buttonBodyColor: '#111827' buttonBodyXPadding: 16 buttonBodyYPadding: 12 buttonBorderColor: '#111827' buttonBorderWidth: 0 buttonBorderRadius: 6 buttonTextColor: '#ffffff' buttonTextFormat: 0 buttonTextFontSize: 16 dividerColor: '#e5e5e5' dividerBorderWidth: 1 textBaseColor: '#374151' textBaseFontSize: 16 textBaseLineHeight: 24 textBaseLetterSpacing: 0 textLinkColor: '#2563eb' heading1Color: '#111827' heading1FontSize: 28 heading1LineHeight: 36 heading1LetterSpacing: -0.5 heading2Color: '#111827' heading2FontSize: 22 heading2LineHeight: 30 heading2LetterSpacing: -0.25 heading3Color: '#111827' heading3FontSize: 18 heading3LineHeight: 26 heading3LetterSpacing: 0 isDefault: true createdAt: '2025-06-29T07:47:39.370Z' updatedAt: '2025-06-29T07:47:39.370Z' affectedEmailCount: 12 ThemeFailureResponse: type: object properties: message: type: string required: - message examples: - message: Theme not found. ThemeStyles: type: object description: >- Flat map of style attributes, matching the attribute names accepted by the LMX `