Claude's design language is built on a single, deliberate choice: warmth over coolness. Where almost every other AI product leans into cold blues, sterile whites, and futuristic gradients, Anthropic built a surface that feels like quality paper.

The foundation is a parchment canvas — #f5f4ed — a warm cream with the faintest yellow-green undertone. It reads as aged book paper rather than a screen. From there, every neutral carries the same warmth: grays are never cool blue-gray, they're olive-tinted (#5e5d59, #87867f), and borders are cream (#f0eee6) rather than neutral gray.

The single brand accent is a terracotta — #c96442 — an earthy burnt orange used sparingly for primary actions and brand moments. It's the visual equivalent of Claude's voice: thoughtful, grounded, human.

• Canvas: Parchment #f5f4ed
• Text: Near-black with olive warmth #141413
• Accent: Terracotta, used rarely #c96442

The type system pairs a medium-weight serif for content with a clean sans for UI — the serif gives every response the gravitas of a published essay.

This is one of the most distinctive choices in the interface: asymmetry between the two speakers.

User messages sit inside a soft, warm-gray bubble — rounded, contained, clearly "yours." Assistant responses have no bubble at all. They render as clean serif text directly on the parchment, like reading a letter. The effect is that Claude's replies feel less like chat messages and more like a thoughtful written response.

A small avatar and the name "Claude" anchor each assistant turn. The text itself does the visual work — generous line-height (around 1.7), comfortable measure, and the serif typeface carry the editorial feeling.