The user wants me to build a playable piano keyboard web app that:
1. Uses the pre-provided tone.min.js library (global Tone)
2. Is controlled by mouse and computer keys
3. Synthesizes notes with an ADSR envelope
4. Has visual key feedback

This needs to be a single HTML file with inline CSS and JavaScript. I'll create a piano keyboard with:
- Visual keys (white and black keys) that respond to clicks
- Computer keyboard mapping to piano keys
- Tone.js for sound synthesis with ADSR envelope
- Visual feedback when keys are pressed

Let me build this step by step:

1. First, check if tone.min.js exists in the current directory
2. Create the index.html file with the piano keyboard implementation

I'll map computer keyboard keys to piano notes. Common mappings:
- White keys: a, s, d, f, g, h, j, k, l, ;, '
- Black keys: w, e, t, y, u, o, p

Or I could use a different octave-based mapping.

Let me create a comprehensive piano keyboard.

I've created a complete piano keyboard web app with the following features:

1. **Visual Piano Keyboard**: 
   - White keys and black keys properly positioned
   - Key labels showing computer keyboard shortcuts
   - Note labels showing the actual note names

2. **Mouse and Keyboard Control**:
   - Click/touch on keys to play
   - Computer keyboard mapping (lower octave with a, s, d, f, g, h, j, k, l, ;, ' for white keys and w, e, t, y, u, o, p for black keys)
   - Upper octave with q, 2, 3, 5, 6, 7, 9, 0, [, ] for white keys and black keys with Ctrl/Shift modifier

3. **ADSR Envelope Controls**:
   - Attack, Decay, Sustain, Release sliders
   - All properly connected to the Tone.js synth

4. **Visual Feedback**:
   - Keys light up when pressed
   - Active state styling for both white and black keys

5. **Additional Features**:
   - Waveform selection (sine, square, sawtooth, triangle)
   - Volume control
   - Octave selection (2-6)
   - Responsive design

The app uses the pre-loaded tone.min.js file and is fully self-contained in a single HTML file with inline CSS and JavaScript.