Space & rule the editorial furniture, not the SaaS kit

Hairlines & air.

The page is a printed journal, not a dashboard. Space between elements does the work that drop-shadows used to. A 1px ink hairline separates ideas; a 3px ink rule opens sections. Nothing is rounded. Nothing glows. Nothing floats.

The ruler §1 · ten steps · clamp-based

01
4
02
8
03
12
04
16
05
24
06
32
07
48
08
64
09
96
10
144

Radii. Two options, one default. §2 · never 12px

sharp · 0
DefaultAll editorial surfaces: card, stat, quote, hero, deck, one-pager. The printed tone requires sharp corners. A rounded corner is a software default.
chamfer · 2
Product UI onlyThe app, dashboards, and input fields use a 2px chamfer. It reads as a control, not as "friendly software." 2px is the entire product radius. Never 4. Never 8.
banned
KilledThe shadcn 10px default, the 12px marketing card, the 16px pill, the rounded-2xl tile. If it looks like a SaaS template, we made a mistake.

Rules, not shadows §3 · strong · normal · muted

Muted hairline
Between two related items: a stat and its caption, or a row in a table. The quiet separator.
Normal rule
Between sections in the same document: essay breaks and column heads. One clean ink line.
Strong rule
Top of every card, top of every deck slide, top of every page. Opens the document.

Banned — the AI-tell list §4 · burn on sight

Radius 12pxThe default Tailwind / shadcn marketing card. Reads AI-generated from across the room.
#EBEBEB 1px soft borderThe "calm SaaS" reflex. Replace with a 1px ink hairline or nothing.
Drop shadows0 4 12 rgba(0,0,0,.12), 0 8 24 rgba(0,0,0,.16), any glow. All banned. Rules replace shadows.
Gradient backgroundsPurple-to-pink, "subtle" tint-to-white. All AI fingerprints.
Rounded stat tilesFour evenly-spaced 12-radius cards with an icon in the top-left.
Centered hero + 3-col belowThe 2019 landing-page reflex. Break it with asymmetry: 1fr 2fr, 3fr 7fr.
"• " bulletsUse filing codes (§1, §2) or mono numerals (01 · 02) or nothing.
Uppercase letter-spaced kicker > 4 times per pageVary with arrows, filing codes, pure italic, or cut.
Source · editorial review, set 26.04 · Scope · every preview, every artifact, every export · Status · enforced