Countdown Timer

# Countdown Timer PRD

## Overview
Build a countdown timer application that supports multiple concurrent timers with preset durations, audio/visual alerts, and data persistence across page reloads.

## Requirements
- Set custom countdown duration with hours, minutes, and seconds inputs
- Start, pause, resume, and reset controls for each timer
- Support multiple concurrent timers running simultaneously
- Name each timer with a custom label
- Preset quick-start buttons: 5 min, 10 min, 15 min, 30 min, 1 hour
- Audio alert sound when a timer reaches zero
- Visual flash/pulse animation when a timer completes
- Animated progress ring showing remaining time visually
- Timer state persists across page reload using localStorage
- Delete individual timers from the list
- Edit timer duration while the timer is paused
- Display total elapsed time across all completed timers
- Keyboard shortcut: Space to start/pause the selected timer
- Lap/split time feature to record intermediate times

## Tech Stack
- HTML, CSS, JavaScript (vanilla or any framework)
- Web Audio API or HTML5 Audio for alert sounds

## Scoring Criteria
- **Functional (40%)**: Timers count down accurately, multiple timers work, alerts fire
- **Quality (20%)**: Accurate timing (no drift), smooth animations, clean code
- **Fidelity (25%)**: All features present including persistence, presets, lap times
- **Speed (15%)**: Time bonus