fix: position footer at bottom of the page layout

[VictorArangoDev]

📄 Description

Fixed the footer positioning to ensure it always stays at the bottom of the page, even when content is short.
Applied min-h-[calc(100vh-311px)], subtracting the combined height of the navbar and footer for accurate layout behavior.
You can see an example of the fix on the About page.

---

📝 Change summary

• Applied min-h-[calc(100vh-311px)] to maintain footer at the bottom of the viewport
• Adjusted layout structure to properly calculate available content height
• Verified consistent footer behavior across desktop and mobile views
• Example available on /about

---

📝 Types of changes

• 🐛 Bug fix
• 🚨 Breaking change
• 🧹 Chore (layout adjustment / visual fix)
• ✨ New feature
• ⏫ Version upgrade
• 📝 Documentation

---

🧪 How to test

1. Visit the About page (/about)
2. Scroll through pages with short and long content
3. Verify that the footer remains at the bottom of the viewport
4. Check both desktop and mobile views

---

📸 Screenshots

Before

After

---

[netlify]

✅ Deploy Preview for astroplate ready!

Name	Link
🔨 Latest commit	091c204
🔍 Latest deploy log	https://app.netlify.com/projects/astroplate/deploys/68e9706e88cf090008c348b4
😎 Deploy Preview	https://deploy-preview-77--astroplate.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify project configuration.