Monday 30 March 2026Afternoon Edition

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Programming & Dev Tools

Someone Built an x86 CPU Emulator Entirely in CSS

No JavaScript. No WebAssembly. Just cascading style sheets computing actual x86 instructions.

Zotpaper1 min read
In a feat of creative engineering that pushes CSS well beyond its intended purpose, a developer has built a functioning x86 CPU emulator written entirely in CSS.

The project dubbed x86CSS demonstrates that CSS increasingly powerful features including custom properties, calc, and complex selector logic can be combined to perform actual computation. The emulator processes x86 instructions using nothing but the browser CSS engine. While obviously not practical, the project joins a proud tradition of proving CSS is accidentally Turing-complete. Previous CSS-only projects have implemented Rule 110 cellular automata and basic logic gates, but a full x86 emulator represents a significant escalation in ambition.

Analysis

Why This Matters

Beyond the obvious fun factor, projects like this reveal hidden computational power in everyday tools. CSS has evolved far beyond simple styling.

Background

The question of whether CSS is Turing-complete has been debated for years. With custom properties and container queries, the language has enough expressive power for arbitrary computation.

What to Watch

How many developers will now try to one-up this by building something even more absurd in CSS.

Sources