# Add Custom code/ CSS correctly

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You won't lose any changes made in Megamog theme by adding Custom Code/CSS directly into these files, since it would be automatically migrated to the updated theme.

</Hint>

Custom Code/CSS can be added to these files:

* File **assets/custom.css.liquid:** Add **Custom CSS** here.
* File **snippets/custom-code-head.liquid:**  Add **Custom Code** *such as* *tracking script, meta tag* before closing tag \</head>.
* File **snippets/custom-code-body.liquid:** Add **Custom Code** *such as tracking script* before closing tag \</body>.

If you made any customizations in these files:&#x20;

* Any files created by a 3rd-party app or customized codes from merchants/dev teams;
* **theme.liquid snippets;**

then you would need to keep track of the files that have been modified in case you need to update your theme when new version is available.