HTML Rendering Fix for Mobile & Tablet

I'm facing layout problems with my HTML project. The issues are prominent on both tablet and mobile devices, and frustratingly, they are consistent across all browsers. I'm in need of an experienced freelancer who can troubleshoot and rectify these rendering issues.

Ideal skills and experience for the job:
- Proficient in HTML, CSS, and JavaScript
- Extensive experience with responsive web design
- Familiar with cross-browser compatibility testing
- Able to optimize layouts for mobile and tablet devices