Responsive Layout

[MOQN]

Responsive styles have not yet been implemented but should be applied.

[MOQN]

• Add padding to the main container to ensure enough white space on the left and right sides in low resolution.
• Hide the top menu items and toggle them with a button.
• Reorganize the footer in low resolution.

[MOQN]

Partially implemented (PR#18).

The top navbar should be toggled.