Layout and space

Layout is where "AI-generated" gets caught. Equal columns, everything centred, every card identical — these are the tells.

Principles

A layout has a primary axis. Left-biased, right-biased, top-heavy, or bottom-weighted. Centre-biased is a default, not a choice.
Asymmetry reads as intentional. Symmetry reads as generated. When in doubt, shift.
Spacing is a scale, not a value. Pick one scale. Use it everywhere. Don't type raw px.
Varied spacing. If every gap is 24px, the page is a template. Mix small, medium, and large gaps within the same layout.
Break the grid on purpose. A page with one element crossing the grid is stronger than a page that never does.

The spacing scale

4pt base. Nine steps. Named by role, not size.

:root {
  --space-3xs: 0.125rem;  /*  2px */
  --space-2xs: 0.25rem;   /*  4px */
  --space-xs:  0.5rem;    /*  8px */
  --space-sm:  0.75rem;   /* 12px */
  --space-md:  1rem;      /* 16px */
  --space-lg:  1.5rem;    /* 24px */
  --space-xl:  2.5rem;    /* 40px */
  --space-2xl: 4rem;      /* 64px */
  --space-3xl: 6rem;      /* 96px */
  --space-4xl: 9rem;      /* 144px */
}

Use gap for sibling spacing. It's cleaner than stacked margins, it participates in flex/grid, and it collapses predictably.
Use margin only for optical adjustments or breaking out of the flow. Never margin for a list of siblings.

Grids

Prefer CSS Grid for page layout, Flexbox for component internals.
grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)) for fluid responsive grids without media queries.
Don't default to 3 columns of equal cards with icon-above-heading-above-copy. This is the AI feature-grid. Break it: vary column widths with grid-template-columns: 1.2fr 1fr 0.8fr, or use a 12-column underlying grid and give each item a different span, or use 4-up with a 2-span hero, etc.
Use named grid areas for complex layouts and rename them at breakpoints.

Asymmetry techniques

Wide left margin. Treat the left as a permanent negative space — narrow column of labels, wide column of content. Labels must NOT be section eyebrows / numbers paired with the heading — that's gate-54-banned. Reserve this technique for body-level micro-labels (caption, footnote, date) alongside body copy.
Hanging headers. ⚠️ Opt-in only. Section labels sit in the left margin; content flows to the right. Permitted only when the user explicitly asks for an editorial / hanging-header layout AND no eyebrow / number / chapter tag sits in the left margin. The eyebrow-left / heading-right pattern is banned by slop-test gate 54 — it's the most reliable templated-editorial AI tell. Default to a stacked single-column section head.
Offset grids. Odd columns wider than even. Or the other way.
Grid-breaks. One element that deliberately extends past a column boundary: a pull-quote, a photograph, a rule, a number.
Generous top, tight bottom (or vice-versa). Sections don't need to be evenly padded.
Alignment coherence. A section head's horizontal alignment should be a deliberate choice that coheres with the body it introduces — match it (left head over left-flush body; centred head over symmetric / centred body) or break from it on purpose (a head that escapes an asymmetric grid). What reads as an AI mistake is the accidental mismatch: a narrow head block auto-centred (margin-inline: auto plus a max-width / ch cap) left floating over full-width, left-flush content beneath it. Centred, hanging, bottom-aligned, and asymmetric heads all stay on the table — the guard is intentionality, not uniformity.

Depth

Depth is weight and scale, not shadow. A heavier weight, a larger size, a warmer hue — these create hierarchy better than drop shadows.
If you use shadow, use one:
- Whisper — 0 1px 2px oklch(20% 0.01 <hue> / 0.05) for hovering cards.
- Hairline — 0 0 0 1px oklch(30% 0.01 <hue> / 0.06) as an alternative to a 1px border.
Never stack multiple shadows. Never use a coloured glow on a light background.
Z-index has six levels, named. Don't freestyle numbers.

:root {
  --z-base:     1;
  --z-raised:   10;
  --z-dropdown: 100;
  --z-sticky:   200;
  --z-modal:    400;
  --z-toast:    500;
  --z-tooltip:  600;
}

Bans

Centre-aligned everything. Headings + body + CTA all centred is the landing-page template every LLM emits.
min-height: 100vh hero with one centred sentence. Stop.
Card-in-card. A bordered container inside a bordered container. Pick one.
Identical feature grid. Three columns, three icons, three two-line headings, three three-line bodies. Change something.
Equal padding on everything. If the card padding equals the section padding equals the page padding, the rhythm is flat.
z-index: 9999 and other ad-hoc z values. Use the scale.
Shadow-on-dark accidental glow. A drop shadow on a dark card creates a glow; that's wrong.

Page-edge clipping

The clipped-edge enrichment archetype (E1) — and any other deliberately overflowing element (full-bleed marquee, oversized headline that exceeds the viewport on small screens, a tilted figure that pushes past a column) — needs a parent that visually shows the overflow without letting the document scroll horizontally.

The default is unsafe: a width: calc(100% + 12vw) figure inside a section with overflow: visible makes the document scroll horizontally on every viewport. The page feels broken on touch devices. Slop-test gate 34 fails on this.

Always pair clipped-edge with a global clip. At the top of the stylesheet:

html { overflow-x: clip; }
body { overflow-x: clip; }   /* fallback for older Safari */

Use overflow-x: clip rather than overflow-x: hidden:

clip preserves position: sticky and position: fixed on descendants.
hidden creates a new scroll container, which breaks sticky and can trap focus on overflowing inputs.

The clipped-edge mockup keeps its visual extension; the page no longer scrolls horizontally. Same pattern works for full-bleed marquees, oversized headlines, and any deliberately-decorative overflow.

The hero or section that contains the overflowing element keeps overflow: visible (so the figure renders past the parent edge); the global clip on html and body is the only safety net needed.

When in doubt

If the layout looks fine but flat, do one of these before shipping:

Add one break-out element.
Unbalance a column width.
Move the primary CTA out of the centre.
Remove a card and replace it with negative space.
Change one section's padding so the rhythm is uneven.

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