The user wants me to build a single-page web app using Tone.js (already provided as tone.min.js) that features:
1. A clickable pentatonic pad grid that triggers a synth voice with reverb
2. A play/stop button that runs an arpeggiator sequence
3. An adjustable tempo control
4. All sound synthesized, no audio files

Let me first check that tone.min.js exists in the current directory.

Good, the file exists. Now let me build a comprehensive single-page web app with:

1. A pentatonic pad grid (clickable) that triggers a synth with reverb
2. A play/stop button for an arpeggiator
3. Adjustable tempo

Let me design a nice UI for this. I'll use a pentatonic scale - let's use C pentatonic across multiple octaves for the grid. The pentatonic scale has 5 notes per octave (C, D, E, G, A), so I can make a nice grid layout.

For the arpeggiator, I'll use Tone.Sequence or Tone.Transport with scheduled events.

Let me create a visually appealing design with:
- A grid of pads (maybe 4x5 or similar layout covering 2 octaves of pentatonic)
- Each pad colored nicely
- A control section with play/stop and tempo
- Reverb effect on the synth

I'll use a PolySynth or MonoSynth with reverb. Let me think about the grid layout...

Pentatonic notes could be arranged like:
- Rows represent scale degrees (C, D, E, G, A)
- Columns represent octaves

Or I could do a more creative layout. Let me do a 5x4 grid (5 notes × 4 octaves = 20 pads) or maybe 5 rows × 3 columns for a cleaner look.

Actually, let me think about this more musically. A common approach is:
- 5 columns (one per pentatonic degree)
- Multiple rows for octaves

Or I could arrange it like a traditional pad controller with rows and columns.

Let me do a nice visual design. I'll make it look modern with gradient colors.

Let me design the pentatonic grid. I'll use C major pentatonic: C, D, E, G, A across 2 octaves (C4-C6), giving us 10 notes. I could arrange them in a 5×2 grid or a 2×5 grid.

Actually, let me make it more interesting - a 4×5 grid with notes from C3 to B5, focusing on pentatonic notes. Or better yet, let me arrange it so each row is a different octave and each column is a scale degree.


5 columns × 4 rows would give me 20 pads total. I could span from C4 to A5 with two full octaves, creating a visually balanced grid that's playable and musically coherent. The5×4 arrangement feels right—five scale degrees across columns and four rows to cover the range, with lower octaves at the top and higher ones below.

For the implementation, I'll use Tone.js to generate notes dynamically and build out the arpeggiator logic. The UI needs the grid of interactive pads, play/stop controls, a tempo slider, and a display showing the current tempo. I'll style everything with CSS grid and flexbox, using a dark background with neon accents to give it that modern synth aesthetic.

The file has been written. Let me verify it's there and looks correct.

Good, the file is there and complete. Let me also verify the script tag for tone.min.js is correct.

Everything looks good. Let me summarize what was built.