Countdown

This tiny codebase exhibits high simplicity, yet significant opportunities exist to professionalize its structure and robustness, especially given the reported security context. * Decouple rendering logic from core time calculations to enhance maintainability and testability of the countdown function. * Salting performance, refactor DOM manipulation by caching critical element selectors outside the periodic `setInterval` loop execution. * The countdown date is rigidly hardcoded; externalize the target date, perhaps using dataset attributes, for better configuration flexibility. * Add robust validation logic to gracefully halt the timer and handle the resulting negative time spans once the target date is reached.