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Quo. A single chartreuse stroke against stark black-and-white editorial layout.

  • Productivity
  • Light theme
  • 8 colors
  • 2 typefaces

Quo runs on an almost ruthlessly monochromatic system — white and off-white canvases, black ink, hairline borders, near-zero elevation — with a single chartreuse accent that behaves like a highlighter, not a decoration. Headlines are editorial in scale (Roobert at up to 88px, tight -0.02em tracking) while UI stays compact in Inter, producing a newspaper-meets-app rhythm: massive confident display type above dense functional surfaces. Components are flat and rectangular with 10px corners; depth is communicated by product screenshots and one soft shadow rather than stacking. The chartreuse (#edfc47) never fills a button — it highlights words inside headlines, tags icons, and draws the eye to emphasis, making the primary action (a black filled button) feel like the default rather than a colorful exception.

Screenshot of Quo (formerly OpenPhone)
Captured from openphone.com on October 11, 2026

Quo design system

Quo

Accent1

  • Emphasis accent on words inside headlines, icon fills, tag highlights — chartreuse that never fills a button, only marks what matters

Neutrals7

  • High-contrast neutral action fill for primary buttons on light surfaces.

  • Announcement bar and dark band backgrounds — near-black for the slim top promo strip

  • Body text and secondary headings — readable but recedes against Press Black for hierarchy

  • Muted helper text, icon strokes, tertiary metadata

  • Hairline borders, dividers, inactive UI edges — the only border color in the system

  • Page canvas and ambient background — warm off-white that softens the stark black type

  • Card surfaces, product screenshot frames, nav background — the raised, clean tier above the canvas

Try a pairing

Pick any two colors from the palette to check whether text stays readable on top.

Aa

Press Black on Highlighter

18.62 : 1 contrast

Background
Text
  • Body textPasses AA 4.5
  • Large textPasses AA 3
  • StrictPasses AAA 7

More DESIGN.md files. Same web, different personalities.