How to customize CSS styling on Squarespace

intermediate 12 min read Updated 2026-03-18

Quick Answer

Customize CSS styling on Squarespace by accessing the Design panel, navigating to Custom CSS, and adding your code modifications. Use browser developer tools to identify element selectors and test changes before implementing them permanently.

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Prerequisites

Basic understanding of CSS syntax and selectors
Active Squarespace website with admin access
Text editor or browser developer tools knowledge
Backup of your current website design

Step-by-Step Instructions

Access the Design Panel

Log into your Squarespace admin panel and navigate to Design from the main menu. This will open the design customization interface where you can modify your site's appearance and styling options.

Make sure you're in the correct website if you manage multiple Squarespace sites.

Open Custom CSS Editor

In the Design panel, scroll down and click on Custom CSS. This will open a code editor window where you can write and paste your custom CSS code. The editor includes line numbers and basic syntax highlighting for easier coding.

The Custom CSS feature is only available on paid Squarespace plans, not on free trial accounts.

Identify Elements to Style

Open your website in a new tab and use browser developer tools (press F12 or right-click and select Inspect Element). Navigate through your site's HTML structure to find the CSS classes and IDs of elements you want to modify. Note down the specific selectors like .header-title or #navigation.

Look for Squarespace-specific class names that often start with prefixes like 'sqs-' or 'Header-' to ensure your styles target the right elements.

Write Your Custom CSS

Return to the Custom CSS editor and write your styling rules. Use proper CSS syntax with selectors, properties, and values. For example:

.site-title {
  color: #ff6b6b;
  font-size: 24px;
  font-weight: bold;
}

Always include the opening and closing braces and semicolons after each property.

Start with small changes and test frequently to avoid breaking your site's layout.

Preview Your Changes

Click the Save button in the Custom CSS editor to apply your changes. Your modifications will be visible immediately on your live site. Open your website in a new tab or refresh existing tabs to see the updated styling in action.

Use your browser's private/incognito mode to preview changes without cached versions interfering.

Test Responsive Design

Use your browser's responsive design mode or manually resize the browser window to test how your custom CSS appears on different screen sizes. Check mobile, tablet, and desktop views to ensure your styling works across all devices. Add media queries if needed:

@media screen and (max-width: 768px) {
  .site-title {
    font-size: 18px;
  }
}

Squarespace templates are mobile-responsive by default, so make sure your custom CSS doesn't break this functionality.

Organize and Document Your Code

Add comments to your CSS code to document what each section does. Use the following format:

/* Header Customizations */
.site-title {
  color: #ff6b6b;
}

/* Navigation Styling */
.header-nav-item {
  text-transform: uppercase;
}

Group related styles together and maintain consistent indentation for easier maintenance.

Keep a backup copy of your custom CSS code in a text file on your computer in case you need to restore or transfer it later.

Common Issues & Troubleshooting

Custom CSS changes not appearing on the website

Clear your browser cache and cookies, then refresh the page. Also check that you've saved the CSS code properly and that there are no syntax errors like missing semicolons or braces.

CSS styles being overridden by default theme styles

Use more specific CSS selectors or add !important to your property values. For example: color: #ff6b6b !important;. You can also inspect the element to see what styles are taking precedence.

Mobile layout breaking after adding custom CSS

Check your CSS for fixed widths or absolute positioning that might not work on smaller screens. Add responsive breakpoints using media queries and test thoroughly on actual mobile devices.

Custom CSS editor showing syntax errors or not saving

Review your CSS code for common syntax errors like unclosed braces, missing semicolons, or invalid property values. Use an online CSS validator to check your code before pasting it into Squarespace.

Prices mentioned in this guide are pulled from current plan data and may change. Always verify on the official Squarespace website before purchasing.

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