Hey Kellie,
X doesn’t support a floating menu or overlay menu design. It can only be achieved using custom CSS. Your custom codes that pushed the content up to achieve a floating menu must have been removed by someone controlling your website.
Please note that we do not provide support for theme customization. If you wish to achieve an overlay navigation effect, please upgrade to Pro and follow the tutorial in this video https://www.youtube.com/watch?v=rSw2g3A2KLc
If you wish to continue using custom CSS, please consult with a developer. Otherwise, remove the custom CSS that is related to the header.
Thank you for understanding.