---
title: "Custom Code Injection"
description: "There are multiple ways to add custom CSS and JS to your Ghost theme, including code injection and custom asset files."
url: "https://www.priority.vision/docs/guides/custom-code-injection"
scope: shared
appliesTo: [Essence, Scope, Thoughts, Feed, Moment, Aspect, OnFlow, Thesis, Format]
lastUpdated: 2026-09-18
---
# Adding Custom CSS & JS: Code Injection and Custom Assets
You can customize your Ghost theme by adding CSS and JavaScript. The recommended way is using Ghost's built-in Code Injection feature, but you can also use custom asset files. Here's how both methods work:
## Method 1: Ghost Code Injection (Recommended)
Code Injection is the safest way to add custom CSS/JS—your changes won't be lost during theme updates.
### Add Custom CSS
1. Log in to Ghost Admin.
2. Go to **Settings → Advanced → Code injection** and click **Edit**.
3. Paste your CSS in the **Site header** editor, for example:
```html
```
### Add Custom JS
1. Go to **Settings → Advanced → Code injection** and click **Edit**.
2. Paste your JS in the **Site footer** editor, for example:
```html
```
## Method 2: Custom Asset Files (Alternative)
You can also add code to `/assets/custom.css` or `/assets/custom.js` in your theme folder.
### How to Use
1. Open `/assets/custom.css` or `/assets/custom.js` in a text editor.
2. Add your custom code.
3. Save the file.
**Important:** Changes made directly to custom asset files may be lost when you update your theme. Always back up your custom files before updating.
### Preserving Custom Asset Changes
1. Back up your `custom.css` and `custom.js` before updating your theme.
2. After updating, compare your backups and reapply any changes as needed.
## Which Method Should I Use?
We **strongly recommend** using Ghost's Code Injection feature:
- Your changes survive theme updates.
- You can manage everything from the Ghost admin panel.
- Less risk of breaking your theme.
Use custom asset files only if you have advanced needs that Code Injection can't cover—and always keep backups!
## Documentation Index
> Fetch the complete documentation index at: https://www.priority.vision/docs/llms.txt
> Use this file to discover all available pages before exploring further.