fix: layout preview missing default style

[motea927]

🔗 Linked issue

#12

❓ Type of change

• 📖 Documentation (updates to the documentation or readme)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

After merging #13, the layout preview lost its default styles. This occurred because the layout preview component is teleported to the body, which prevents the shadow DOM styles from being applied correctly. To address this, we introduced a dynamic style injection to ensure the layout preview retains its default styles.

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly (for new feature).