🎹 Neon Piano

A playable one-octave neon synth keyboard you can perform with directly — no game mode, no falling tiles, no score. Just press a key (mouse, touch, or keyboard) and a real square-wave tone rings out and sustains for as long as you hold. The full C → high C with all five sharps is laid out across one row, with a 9-octave shifter so you can roam from sub-bass to piccolo range. Cyberpunk visuals with a cyan→magenta gradient palette, CRT scanlines, and the Orbitron typeface — same family as the Neon Tiles games, designed as their landscape-orientation companion instrument.

🎮 How to Play

It plays like a real keyboard. Press = note on, release = note off.

• Mouse / Click — Click and hold a tile to sustain the note; release to stop.
• Touch — Same gesture on mobile/tablet. Each touch is independent.
• Keyboard (white keys) — A S D F J K L ; map to C D E F G A B C (one full octave, do→do).
• Keyboard (black keys / sharps) — W E Y U I map to C♯ D♯ F♯ G♯ A♯, sitting visually between their flanking white keys.
• Octave down — Q (or the - OCT button)
• Octave up — P (or the + OCT button)
• Jump directly to an octave — 1 through 9 on the number row, or click the colored number buttons. Default is octave 4 (middle C).

✨ Features

🎵 Real Sustained Synthesis, Not Sample Playback

• Built on the Web Audio API with live OscillatorNode square-wave synthesis — no audio files, just math.
• Each note actually consists of two oscillators: a fundamental (volume 0.10) and an octave overtone (volume 0.025), mixed to give the tone a slight 8-bit-game richness without losing its edge.
• Notes sustain indefinitely while you hold the key, with a 120 ms exponential release ramp on key-up — no sudden cutoffs, no artificial decay.
• Polyphonic: hold multiple keys at once (mouse + keyboard + touch all stack) and every note rings simultaneously.

🎹 Full Chromatic Octave, Sharps Included

• 8 white tiles arranged across the full keyboard width, labeled with their pitch (e.g., C4), keyboard hotkey (e.g., A), and matching keyboard letter.
• 5 black tiles overlaid above the white-tile boundaries at correct piano positions (between C–D, D–E, F–G, G–A, A–B). Geometry is computed from the actual layout math ((90vw - 7×0.6vw gap) / 8 white keys), so the sharps land exactly on the boundary, not approximately.
• Black-tile colors are computed as the average of their two flanking white keys' colors, so the cyan→magenta gradient flows smoothly across all 13 keys — not just the white ones.

🌐 9-Octave Range

• Shift the entire keyboard from octave 1 (deep sub-bass, C1 = ~33 Hz) to octave 9 (well into ultrasonic territory, C9 = ~8.4 kHz).
• The high C of any octave is the low C of the next, so you always have 8 do→do white keys regardless of where you are.
• Number buttons across the top are themselves painted along the same cyan→magenta gradient, so you can see at a glance where on the spectrum you are.

🎨 Polished Neon Visuals

• CRT scanline overlay on the whole screen — subtle horizontal lines at 1 px / 3 px spacing, giving the synth a retro arcade-cabinet feel.
• Each tile has its own neon tube look: dark interior with scanline texture in the tile's color, glowing border, and an outer halo on press.
• Active state is dramatic: the whole tile fills with its color, the label flashes white with a glowing text-shadow, and the outer halo doubles in size.
• Gradient title ("NEON PIANO") across the top in the same cyan → purple → magenta sweep used by the Neon Tiles game series.
• Octave indicator buttons highlight in their own color when selected, with a strong outer glow.

🧠 Smart Input Handling

• Audio context warmup: a 10 ms silent sample plays at first user gesture so the audio thread is spooled up before the first real note — no first-press latency.
• latencyHint: 'interactive' on the AudioContext for the lowest practical latency.
• e.repeat filtered on keydown so holding a key doesn't retrigger the note 30 times per second.
• window blur releases everything — switching tabs or apps won't leave a note hanging.
• mouseleave also counts as release so dragging off a tile won't strand a sustained note.
• Octave changes release all currently-held notes cleanly before rebuilding the keyboard, so no stuck tones from before the shift.

📱 Multi-Touch + Multi-Input

• Touch events use passive: false with preventDefault so the keyboard doesn't trigger page scroll or zoom on mobile.
• Multiple touches can hold multiple keys independently — play actual chords with two thumbs or all ten fingers.
• Mouse, touch, and physical keyboard all coexist — you can hold a chord with your left hand on the keyboard and add notes with your right hand on the touchscreen.

🛠️ Tech Stack

• Pure HTML / CSS / JavaScript — zero dependencies, zer