What steps should I take before modifying theme files?

Each Pixel Union theme includes a wealth of features and settings. With these extents also come limitations, so merchants often modify theme files to achieve new enhancements.

The most reliable way to adjust theme files is to hire a vetted expert, but the next best approach would be to make the adjustment yourself. To safeguard your storefront while trying out adjustments, start with the latest version available, protect your work by creating backups, and track your changes.

Use Shopify’s built-in features first

Before modifying theme files, check whether the change can already be made using:

• Theme settings
• App embeds
• Theme blocks
• Sections
• Metafields
• Dynamic sources
• Shopify apps

Many customizations no longer require editing theme code thanks to Shopify’s Online Store 2.0 architecture.  

Start with the latest supported available

Before adding custom code, make sure you’re working from the latest supported version of your Pixel Union theme whenever possible. Newer versions often include bug fixes, improved compatibility with Shopify, accessibility enhancements, and additional built-in features that may reduce or eliminate the need for customizations.

Why

• New theme versions include bug fixes
• Security improvements
• Accessibility improvements
• Compatibility with the latest Shopify platform updates
• New features that may eliminate the need for custom code

Protect your work by creating backups

Creating duplicates of your theme is always advised before making any changes to the theme files. Duplicates of the theme not only serve as references for the theme's default state but also as a complete backup for the adjusted theme. If errors are encountered, publish the previous theme or use it to copy the default code to the adjusted theme to restore function, styling, etc.

Never edit your live theme first

Whenever possible, make changes on a duplicate theme instead of your published theme.

Benefits:

• customers never see unfinished work
• easier troubleshooting
• safer testing
• no storefront downtime

Track your changes

Record the adjustments you make to the theme files. This can be simple as a document file with dates and notes with a summary of a modification. Shared documents, like those available through Google Docs, are valuable for tracking changes when working in teams.

Use:

• Google Docs
• Notion
• GitHub
• Markdown file
• project documentation

Comment your code 

Liquid

{% comment %}
Custom size guide
Added Aug 2026
{% endcomment %}

CSS

/* Added Aug 2026
Increase announcement bar height */

JS

// Added Aug 2026
// Custom product carousel

Understand Support limitations

Pixel Union supports the original functionality of our themes.

• If issues occur after modifying theme files:
• support may ask you to reproduce the issue on an unmodified theme
• custom code isn’t covered under theme support third-party developers are responsible for their customizations

If you're using AI generated code

Tools like ChatGPT and AI coding assistants can help generate Shopify code, but the output should always be reviewed and tested before publishing. AI-generated code may:

• conflict with existing theme functionality
• reduce performance
• create accessibility issues
• stop working after future theme updates

Always test AI-generated changes on a duplicate theme before publishing.