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Synthwave sunset · step-3.7-flash

Create an animated synthwave sunset: a glowing gradient sun with scanlines setting over an infinite neon grid that scrolls toward the viewer, with a starfield and a reflected horizon.

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transcript · 4 messages
user

Create an animated synthwave sunset: a glowing gradient sun with scanlines setting over an infinite neon grid that scrolls toward the viewer, with a starfield and a reflected horizon.

assistant
thinking
The user wants a single-page web app with an animated synthwave sunset effect. It needs to be fully self-contained in one index.html file with inline CSS and JS, no external resources.

Let me design this:
1. A glowing gradient sun with horizontal scanlines
2. An infinite neon grid that scrolls toward the viewer (perspective grid)
3. A starfield with twinkling stars
4. A reflected horizon (sun reflection on the grid)

I'll use Canvas API for the main rendering since it's efficient for this kind of animation.

Key visual elements:
- Background: dark sky gradient (deep purple/blue/black)
- Sun: large glowing circle with gradient colors (pink/orange/purple) with horizontal scanlines cutting through it
- Grid: perspective grid on the "ground" area with neon lines (cyan/magenta) scrolling toward viewer
- Stars: randomly placed dots that twinkle
- Reflection: mirror the sun on the grid with opacity

I'll create a full-screen canvas animation with requestAnimationFrame.

Let me write the complete index.html file.
write /workspace/index.html (8798 bytes)
toolResult

Successfully wrote 8798 bytes to /workspace/index.html

assistant
thinking
The file has been written successfully. Let me provide a concise summary to the user about what was created.

Created `index.html`. The scene features: - **Sky / Ground** — vertical gradient from deep indigo to neon magenta above a dark horizon - **Sun** — radial + linear gradient disc with animated horizontal scanlines (using `source-atop`) - **Neon Grid** — perspective-mapped vertical and curved horizontal lines scrolling depth-first with edge-to-edge gradient strokes - **Horizon glow** — bright magenta line with soft bloom - **Starfield** — 220 stars with independent twinkle phases - **Reflection** — a flipped, scaled, faded duplicate of the sun + scanlines drawn into the ground plane - **Vignette** — radial darkening to frame the view Everything runs off a single `<canvas>` with `requestAnimationFrame`, no external resources, and responds to window resizing.

TAKE IT TO CODE

A single self-contained HTML file — copy it and open in any browser, or reuse the prompt with your own pi-agent run.

RUN

modelstep-3.7-flash
vendorStepFun
harnesspi-agent
generated2026-07-22

EVALUATION

4/5 working

Synthwave sunset with glowing gradient sun, scanlines, neon grid, starfield, and horizon reflection; static, no visible grid scroll or input response.

Vision grade · anthropic/claude-sonnet-5

MEASUREMENTS

Raw readings from the capture, not a verdict — the grade above is the only judgement. Percentages are how much of the screen changed; the measure under-reports sparse motion on a dark background.

idle motion0.1%
on click0.0%
on drag0.0%
on wheel0.0%
on enter + space0.0%
on arrow keys0.0%
on w/a/s/d0.0%
frame spread32.3 / 255
console errors0
js errors none

METRICS

runtime27.2s
tokens in3.8k
tokens out3.6k
cached2.8k
cost / run$0.0051