How to Override Theme CSS Without Losing Changes After Theme Updates

Editing core theme files directly can cause your changes to disappear after updates. This guide shows the safe way to customize CSS.

Best Practice: Use Custom CSS Files

Go to Online Store → Themes → Edit Code → Assets

Create or edit:

• custom.css or base.css

Add Your CSS at the Bottom

/* Custom overrides */
.product-title {
  font-size: 20px;
  color: #111;
}

Never Edit These Files

• theme.liquid core markup
• Vendor app CSS
• Minified core CSS