> For the complete documentation index, see [llms.txt](https://4sh-templates.gitbook.io/opulent-os2.0/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://4sh-templates.gitbook.io/opulent-os2.0/add-custom-code-css-correctly.md).

# Add Custom code/CSS correctly

* 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:

"For any files generated by a third-party app or custom code developed by merchants or development teams;

theme.liquid snippets;

you'll need to manually transfer the custom code/CSS to the updated theme. Unfortunately, Shopify doesn't offer a workaround for this."

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