# Theme Development
> Build, customize, and deploy Shopify themes. Use this skill for creating new themes, modifying existing themes, understanding theme architecture, working with sections/blocks, and optimizing theme performance. Covers Skeleton theme, Dawn theme, layouts, templates, and the theme editor customization experience.
- Skill: `dragnoir/theme-development` (Agent Skill, multi-file: 4 files)
- Install (CLI): `npx skillmds@latest add dragnoir/theme-development`
- Raw SKILL.md: https://api.skillmd.com/api/skills/dragnoir/theme-development/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: DevOps & Infra
- License: MIT
- Author: dragnoir (https://skillmd.com/u/dragnoir)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/dragnoir/theme-development
---
# Shopify Theme Development
## When to use this skill
Use this skill when:
- Creating a new Shopify theme from scratch
- Modifying or customizing an existing theme
- Understanding Shopify theme architecture
- Working with sections, blocks, and templates
- Setting up the development environment
- Deploying themes to a Shopify store
- Optimizing theme performance
## Theme Architecture Overview
### Directory Structure
A Shopify theme must follow this structure:
```
your-theme/
├── assets/ # CSS, JS, images, fonts
├── config/ # Theme settings (settings_schema.json, settings_data.json)
├── layout/ # Layout files (theme.liquid required)
├── locales/ # Translation files (en.default.json, etc.)
├── sections/ # Reusable section components
├── snippets/ # Reusable code snippets
└── templates/ # Page templates (JSON or Liquid)
└── customers/ # Customer account templates
```
**Minimum Requirements:** Only `layout/theme.liquid` is required for upload.
### Component Hierarchy
```
Layout (theme.liquid)
└── Template (product.json)
└── Sections (product-details.liquid)
└── Blocks (price, quantity, add-to-cart)
└── Snippets (icon-cart.liquid)
```
## Getting Started
### 1. Initialize a New Theme
Use the Skeleton theme as a starting point:
```bash
# Clone the Skeleton theme
shopify theme init my-theme
# Navigate to your theme
cd my-theme
```
The [Skeleton theme](https://github.com/shopify/skeleton-theme) is minimal and follows Shopify best practices.
### 2. Start Development Server
```bash
# Start local development with hot reload
shopify theme dev
# Connect to a specific store
shopify theme dev --store your-store.myshopify.com
```
This opens a local preview URL with live reloading.
### 3. Push to Shopify
```bash
# Upload as a new theme
shopify theme push --unpublished
# Push to an existing theme
shopify theme push --theme THEME_ID
```
## Key Concepts
### Layouts
Layouts wrap all pages. The main layout file is `layout/theme.liquid`:
```liquid
{{ page_title }}
{{ content_for_header }}
{% sections 'header-group' %}
{{ content_for_layout }}
{% sections 'footer-group' %}
```
### JSON Templates
Modern themes use JSON templates that reference sections:
```json
// templates/product.json
{
"sections": {
"main": {
"type": "product-details",
"settings": {}
},
"recommendations": {
"type": "product-recommendations",
"settings": {}
}
},
"order": ["main", "recommendations"]
}
```
### Sections
Sections are reusable, customizable modules:
```liquid
{% schema %}
{
"name": "Featured Collection",
"settings": [
{
"type": "collection",
"id": "collection",
"label": "Collection"
},
{
"type": "range",
"id": "products_to_show",
"min": 2,
"max": 12,
"step": 1,
"default": 4,
"label": "Products to show"
}
],
"presets": [
{
"name": "Featured Collection"
}
]
}
{% endschema %}
{% if section.settings.collection != blank %}
{% for product in section.settings.collection.products limit: section.settings.products_to_show %}
{% render 'product-card', product: product %}
{% endfor %}
{% endif %}
```
### Blocks
Blocks allow merchants to add, remove, and reorder content:
```liquid
{% schema %}
{
"name": "Slideshow",
"blocks": [
{
"type": "slide",
"name": "Slide",
"settings": [
{
"type": "image_picker",
"id": "image",
"label": "Image"
},
{
"type": "text",
"id": "heading",
"label": "Heading"
}
]
}
]
}
{% endschema %}
{% for block in section.blocks %}
{{ block.settings.heading }}
{% endfor %}
```
## Best Practices
### Performance
1. **Lazy load images** - Use `loading="lazy"` for images below the fold
2. **Optimize images** - Use `image_url` filter with appropriate widths
3. **Minimize render-blocking resources** - Defer non-critical CSS/JS
4. **Use native browser features** - Prefer CSS over JavaScript when possible
```liquid
{{ product.featured_image | image_url: width: 800 | image_tag:
loading: 'lazy',
widths: '300, 500, 800, 1200',
sizes: '(max-width: 600px) 100vw, 50vw'
}}
```
### Accessibility
1. Use semantic HTML (``, `