Shopify theme customisation sits on a spectrum from zero-code to full Liquid development. Where you land on that spectrum should be driven by what you are trying to achieve and your risk tolerance for breaking a live store. This guide maps out what is possible at each level, where the danger zones are, and when it makes sense to bring in a developer.
Theme Editor vs Liquid Editing
The Shopify theme editor (Customise in the admin) is a visual interface for making changes that theme developers explicitly made configurable. It is entirely safe — you cannot accidentally break your storefront from within the theme editor, and changes are preview-able before publishing.
Liquid editing (via the code editor in admin or a local development environment) accesses the raw theme files. It is powerful but carries risk — a syntax error in a critical file renders your store unusable until fixed.
| Task | Theme Editor | Liquid Code Edit |
|---|---|---|
| Change colours, fonts, spacing | Yes (via settings) | Yes (for fine control) |
| Reorder page sections | Yes | Not needed |
| Add/remove homepage sections | Yes | Not needed |
| Create a new section type | No | Yes |
| Add conditional logic (show X if logged in) | No | Yes |
| Modify product page layout | Partially | Yes (full control) |
| Add custom CSS classes | Via custom CSS field | Yes |
| Integrate a third-party script | Via theme settings (limited) | Yes (theme.liquid) |
Online Store 2.0 vs Legacy Themes
OS 2.0 (introduced 2021, now standard) uses JSON templates that reference sections by name. This means sections can be added to any page type — product pages, collection pages, blog posts — directly from the theme editor, without code changes. App blocks allow third-party apps to insert content via the theme editor without modifying Liquid files.
Legacy themes use Liquid-only templates. Adding a section to a product page requires editing the product template file directly. App integrations typically require copy-pasting code snippets into specific template locations. If you are on a legacy theme, migrating to an OS 2.0 theme reduces ongoing customisation friction significantly.
Always Back Up Before Editing
Before making any code-level changes: duplicate the theme in Shopify admin (Online Store → Themes → Actions → Duplicate). This creates a backup you can restore instantly. Never edit the published live theme directly without a backup copy. For teams making frequent changes, a Git-based workflow with a local development environment (using the Shopify CLI) provides full version history and the ability to preview changes before pushing to the live theme.
For ongoing theme development and customisation on a planned roadmap, OneOnic’s Shopify development team works within version-controlled theme environments as standard practice.
Common Customisation Requests and What They Require
Custom product page layout — typically requires Liquid section editing. Theme editor rarely provides enough granularity for significant layout changes.
Sticky add-to-cart bar — usually achievable by editing a section and adding CSS/JavaScript, or via a free app. Estimated effort: half a day for a developer.
Custom collection filtering — if the theme does not support it natively, this requires Liquid work or a filtering app (like Boost Commerce or Searchpie). More complex than it appears.
Size guide popup — typically a snippet + CSS + a small Liquid addition to the product template. One to two hours of developer time.
Frequently Asked Questions
Will Shopify theme updates overwrite my customisations?
Shopify theme updates are not applied automatically to themes with customisations — updates are published as new theme versions in your theme library, and you choose whether to apply them. If you update, any code-level customisations in modified files need to be manually re-applied to the new version. This is one reason to document all custom changes clearly.
Can I customise a third-party paid theme?
Yes. Once purchased, a Shopify theme is yours to modify. There is no licensing restriction on code-level customisation. The one practical consideration is that heavy customisation makes future theme updates harder to apply — the more you diverge from the original, the more manual work each update requires.
What is the difference between a section and a block in Shopify?
A section is a standalone, full-width module on a page — a hero banner, a product grid, a testimonials row. A block is a configurable child element within a section — an individual testimonial card, a product feature bullet, a tab within a tabbed section. Blocks are added, removed, and reordered within their parent section in the theme editor.
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