OpenAI vs Substack
54 token-level differences between these two design systems.
Background
#ffffff → #ffffff Text
#000000 → #363737 Brand
#000000 → #ff6719 Border
rgba(0,0,0,0.1) → rgba(0, 0, 0, 0.10) Display font
OpenAI Sans → Cahuenga Body size
16px → 19px colors 48 changed
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bg-soft #f1f1f1 → #f6f6f3 ~
surface #fafafa → #ffffff ~
text #000000 → #363737 ~
text-strong #000000 → #1a1a1a ~
text-muted #5d5d5d → #878787 ~
text-faint #b4b4b4 → #a8a8a8 ~
brand #000000 → #ff6719 ~
brand-hover #1a1a1a → #e85412 ~
border rgba(0,0,0,0.1) → rgba(0, 0, 0, 0.10) ~
border-soft rgba(0,0,0,0.08) → rgba(0, 0, 0, 0.06) ~
border-strong rgba(0,0,0,0.16) → rgba(0, 0, 0, 0.20) ~
success #10a37f → #0d8050 ~
danger #cc2525 → #dc2626 ~
info #3a3a3a → #2563eb +
bg-elev #fafaf7 +
bg-cream #fbf9f4 +
surface-warm #fafaf7 +
text-soft #666c70 +
text-link #363737 +
brand-deep #cc4a0e +
brand-tint rgba(255, 103, 25, 0.10) +
brand-tint-strong rgba(255, 103, 25, 0.18) +
border-warm rgba(0, 0, 0, 0.08) +
selection-bg rgba(255, 103, 25, 0.20) +
shadow-soft rgba(0, 0, 0, 0.06) +
shadow-medium rgba(0, 0, 0, 0.10) +
reading-rule rgba(0, 0, 0, 0.08) −
bg-section #f7f7f7 −
surface-card #ffffff −
surface-hover rgba(0,0,0,0.04) −
surface-press rgba(0,0,0,0.08) −
text-subtle #8e8e8e −
text-on-brand #ffffff −
text-on-dark #ededed −
brand-active #2c2c2c −
brand-on-dark #ffffff −
accent #10a37f −
accent-hover #0d8a6b −
accent-soft #d6f3e8 −
link #000000 −
link-hover #5d5d5d −
link-visited #000000 −
scrim rgba(0,0,0,0.5) −
shadow-card rgba(0,0,0,0.06) −
shadow-elev rgba(0,0,0,0.10) −
shadow-modal rgba(0,0,0,0.20) −
warning-soft #fdf3e7 −
danger-soft #fae5e5 typography 5 changed
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display {"family":"OpenAI Sans","size":48} → {"family":"Cahuenga","size":56} ~
h1 {"family":"OpenAI Sans","size":40} → {"family":"Cahuenga","size":40} ~
h2 {"family":"OpenAI Sans","size":32} → {"family":"Cahuenga","size":32} ~
body {"family":"OpenAI Sans","size":16} → {"family":"Spectral","size":19} ~
label {"family":"OpenAI Sans Mono","size":12} → {"family":"Monaco","size":13} radius 1 changed
~
button 8px → 6px spacing identical
No differences.