To implement dark mode, use CSS custom properties (variables) for color schemes and media queries (prefers-color-scheme) to detect system theme preferences. Provide a toggle option for users to switch manually, storing their preference locally to persist across sessions.

These questions represent a mix of foundational knowledge and practical skills in front-end development, reflecting the breadth and depth expected in interviews at top tech companies. Remember, the key to success lies not only in knowing the answers but in understanding the underlying concepts and being able to discuss and apply them in various scenarios.