If your changes to a GitHub Pages site are not showing up after pushing to the repository, there are a few possible causes:
1) Caching: Sometimes, changes may not be immediately visible due to caching. Try clearing your browser cache or waiting a few minutes before refreshing the page.
2) DNS Propagation: If you have recently created or changed the repository that serves your GitHub Pages site, it may take a few minutes for the changes to take effect due to DNS propagation.
3) Source Branch: Make sure that the source branch for your GitHub Pages site is correctly configured. The source branch is specified in the repository's settings, under the "GitHub Pages" section.
4) Theme: If you are using a theme for your GitHub Pages site, make sure that you have pushed the latest version of the theme to the repository.
If none of these steps resolve the issue, try checking the GitHub Pages build logs for errors or further information.