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 — enough to read as a control, not enough to read 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 · three weights · ink only

Hairline · 1px
Between two related items — a stat and its caption, a row in a table. The quiet separator.
Bar · 2px
Between sections in the same document — essay breaks, column heads. Rarely used. A mid-weight is almost always wrong.
Masthead · 3px
Top of every card, top of every deck slide, top of every page. Opens the document. The only rule with loud weight.

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