I'm a product design student. I'm not familiar with the terminal or writing code. Please build this for me with HTML, CSS, JavaScript and native Web Audio. Make a simple, usable browser page, with no external libraries or internet services. Sound should start only after I click. Use comfortable initial levels. I need to play with the result, not read code. Build a sound mixer using these four local audio files: ../../assets/audio/City_Loop_Light-rain_20s.mp3, ../../assets/audio/Forest_Loop_After-rain_20s.mp3, ../../assets/audio/Water_Loop_Light-swell_20s.mp3 and ../../assets/audio/Forest_Loop_Frost_20s.mp3. Each sound needs on/off and its own level slider. Several sounds can play together. Add a global stop and an output level. Keep the audio engine separate from the interface so we can change the design later. Show the file's duration before playback. Check stop, restart and loop boundaries. Keep it local and runnable without a build step.