- ✏️ Update HTML title to "Invoice Email Sender"
- 💄 Change font from 'Roboto' to 'Lora' and revise color scheme
- 🌈 Refine button and input styles with new colors, borders, and transitions
- ✨ Implement tab functionality with CSS rules, HTML structure, and JS listeners
- 📑 Revamp status bar style and content
- 🔨 Refactor main.py:
- 🗃️ Adapt read_yaml and write_yaml for enhanced 'email' and 'email_template' structure
- 🔧 Modify handle_data for structure changes
