We need to create index.html with embedded CSS and JS and load tone.min.js via script src="tone.min.js". Then implement piano keyboard: probably draw keys (white and black) as divs; map mouse clicks and keyboard keys (like ASDF etc) to notes. Use Tone.js to synthesize: use a synth with ADSR envelope.

We need to ensure tone.min.js is in current directory. Let's list files.

We have tone.min.js.

Now we need to write index.html. We'll create HTML skeleton with style and script.

Implement basic piano: perhaps one octave (C4 to B4) with keys. We'll map QWERTY row: A S D F G H J K L ; etc to notes. Simpler: use computer keys: 'a','w','s','e','d','f','t','g','y','h','u','j','k' typical piano mapping. Provide visual feedback: highlight key when pressed.

Implement using Tone.Synth with envelope: attack 0.01, decay 0.2, sustain 0.5, release 1.

Add event listeners for mouse down/up on key elements, and keydown/keyup globally.

Will need to map note names to frequencies perhaps using Tone.Note (or just use note string in synth.triggerAttackRelease).

Implementation steps:

- HTML: container div with class 'piano', each key as div with class 'white-key' or 'black-key' and data-note attribute.

- CSS: style for white and black keys, positions. Use position: relative for piano container; white keys width 40px, height 200px; black keys width 30px, height 120px, positioned absolute over white keys.

Simplify: layout using flexbox for white keys, and overlay black keys with position absolute.

We'll design layout for one octave: notes: C4 D4 E4 F4 G4 A4 B4 (white) and C#4 etc.

Keyboard mapping: use letters: a s d f g h j k; maybe map corresponding.

I'll define mapping object.

Implement JS:

- const synth = new Tone.Synth({envelope: {attack:0.01, decay:0.2, sustain:0.5, release:1}}).toDestination();

- function playNote(note){ synth.triggerAttackRelease(note, "8n"); }

Add event listeners to keys: mousedown triggers note and adds class 'active'; mouseup removes class.

Add keydown/keyup: track which key is down to avoid repeat.

We need to ensure Tone start on user interaction: call Tone.start() on first click.

Implement.

Now create index.html via write.