Hi @Keegan Clarke ,
Welcome to Q&A forum!
To save your customizations in SharePoint, you need to apply your changes using a method that persists beyond page refreshes. Since changes made directly in the browser's developer tools are temporary, consider using SharePoint Framework (SPFx). Since you are using modern SharePoint, consider developing a custom web part using the SharePoint Framework. This allows you to implement your styles and functionality in a way that is supported by SharePoint.
For your reference:
Customizing "modern" site pages
Good day!
If the answer is helpful, please click "Accept as Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.