# Child Theme If you need to modify core files or just need a better way to manage custom CSS, we recommend using the child theme. The fastest way to install the child theme is by going to Appearance -> Themes -> Add New Theme & Activate Child theme. Now you have the child theme actived, you can start add your custom CSS into the child theme style.css file, or your custom PHP code in functions.php file, via Appearance -> Editor. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://7iquid.gitbook.io/carmelina-wordpress-theme/basic-installation/child-theme.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.