Fix Scrolling Issues on Website

I need help resolving a scrolling issue on my website. The scrolling gets stuck on the galleries and tools pages. This issue started after I added an iframe with a custom app.

Ideal Skills and Experience:
- Strong expertise in CSS and JavaScript
- Experience with iframes and integrating custom apps into websites
- Problem-solving skills to diagnose and fix scrolling issues
- Familiarity with web development and debugging tools

the site is complete tiling.uk

i have uploaded a text document with the style sheet it is in the correct format on the hosting site though