Build a mindfulness meditation timer using HTML5, CSS3, and JavaScript. Create a serene, distraction-free interface with nature-inspired design. Implement customizable meditation sessions with preparation, meditation, and rest intervals. Add ambient sound options including nature sounds, binaural beats, and white noise. Include guided meditation with customizable voice prompts. Implement interval bells with volume control and sound selection. Add session history and statistics tracking. Create visual breathing guides with animations. Support offline usage as a PWA. Include dark mode and multiple themes. Add session scheduling with reminders.