Converting demo1.html to Jekyll Format

Convert onepage.html into a Jekyll-friendly onepage.md format, following patterns from demo1.md.

Steps:

1. Analyze the existing onepage.html structure
2. Extract the main sections and components
3. Create a Jekyll-compatible onepage.md file with frontmatter
4. Define all necessary sections as variables in the frontmatter
5. Structure the main content using includes for sections