adjusted styling to address #1

[Silvyre]

This PR addresses issue #1 (UI responsivity: header text wrapping issues on smaller resolutions).

• CSS was adjusted to prevent textual overlap and conflict at smaller resolutions

[vitokhangnguyen]

Thank you for your contribution!
Responsiveness is absolutely an important factor of a modern web application. Although currently, my app does not support dragging and dropping of notes on small devices or devices other than computers, I accepted your code since I think it might be helpful in future in which I plan to expand my app to said devices.