fix: resolve waitlist modal overlap with navbar

[AnxhDarji]

What does this PR do?

This PR fixes the waitlist modal overlap issue caused by the fixed navbar on desktop view.

Changes made

• Updated modal positioning to account for the fixed navbar height
• Added responsive height handling to prevent clipping at different browser zoom levels
• Enabled internal modal scrolling when content exceeds the viewport height

Result

• The waitlist form no longer gets hidden behind the navbar
• Modal content remains accessible and properly visible at 100%, 110%, and 125% zoom levels
• Existing UI, responsiveness, and functionality remain unchanged

Type of change

• 🐛 Bug fix
• ✨ New feature
• 📝 Content (mentor / resource / storyboard)
• 📖 Documentation
• 🎨 Style / UI improvement
• ♻️ Refactor

Checklist

• I've tested my changes locally (npm run dev)
• My code follows the project style guide
• No console errors introduced

Screenshots

Before

After

Fixes #68

[vercel]

@AnxhDarji is attempting to deploy a commit to the HerStack's projects Team on Vercel.

A member of the Team first needs to authorize it.

[AnxhDarji]

Fixed the navbar overlap issue affecting the waitlist modal on desktop view. Tested across multiple zoom levels.

Happy to contribute to HerStack

[Karanjot786]

Hey @AnxhDarji! Saw your work on GSSoC 2026.

We are building TermUI, a TypeScript terminal UI framework with React-style hooks and JSX, rendered entirely in the terminal.

We have 55 unassigned GSSoC issues open, including well-scoped bug fixes with clear repro steps. Your JavaScript background transfers directly.

• Open issues (GSSoC 2026)
• TermUI on GSSoC

Karanjot, TermUI maintainer