Story 5.4: Ensure Responsive Design for Presentation Viewer

[ajelinek]

Part of #10

As a user, I want to view presentations effectively on various devices, including desktops, tablets, and mobile phones, with a responsive layout.

Acceptance Criteria:

• Slide content reflows and scales appropriately for different viewport sizes.
• Navigation controls are accessible and usable on all screen sizes.
• Font sizes, spacing, and image scaling are responsive.
• No horizontal scrolling is required on smaller screens for primary content.

Test Cases:

• E2E test: View presentation on emulated mobile, tablet, and desktop sizes; verify layout and usability.
• Visual regression testing (optional): Catch unintended layout shifts across devices.

Constraints:

• Requires careful CSS design using media queries, flexible units, and potentially container queries.

Dependencies:

• All UI components (Slide.astro, NavigationControls, etc.).
• Project's global CSS and styling approach.