Design Sense

---
name: design-sense
description: Compose interfaces that hold together — skeleton before aesthetics, one alignment per row, sizing by declaration. Use when building or reviewing any UI component, fixing "it looks off but I cannot say why", or adding an element to an existing layout.
---

# Design sense

Most UI that "looks off" is not ugly. It is **structurally inconsistent** — two
alignments in one row, two things that should match sized by different
mechanisms, a number column that shifts with its digit count. The viewer cannot
name it and reports a feeling. This skill is how to not create that feeling.

Every rule below came from a real defect. None is a preference.

---

## 1. The order of operations

Build in this order. Doing them out of order is how a layout ends up needing to
be rebuilt rather than adjusted.

1. **Skeleton.** Boxes, widths, alignment. No colour, no type, no borders. If
   it is wrong here, no amount of styling saves it — and styling makes the
   wrongness harder to see, because now there is something to look at.
2. **Rhythm.** One spacing scale. Every gap is a step on it.
3. **Hierarchy.** Size and weight decide what is read first. Still no colour.
4. **Theme.** Colour, borders, shadow — applied last, on top of a layout that
   already works in greyscale.

**The test:** turn the colour off. If you cannot tell what matters, the problem
is in step 3, and reaching for a brighter accent will not fix it.

---

## 2. Composition rules

### One alignment per row

A row that aligns its children to the bottom, containing a label aligned to the
centre, containing a note on its own baseline, is three alignments in one line.
Nobody can name it; everybody sees it.

Pick one — `items-center` for controls, `items-baseline` for text of different
sizes — and let every child inherit it. A child that needs to differ says so
explicitly (`self-center`), and that exception should be rare enough to notice.

**Failure seen:** a bid bar with the row at `items-end`, the label at
`items-center`, and the caption on neither.

### A child in a top-aligned row must declare itself

Add an element to a row aligned at the top and it will sit flush against the
top edge and clip. Nothing is wrong with the element; it never said where it
goes. `self-center` is not decoration — it is the element stating its place.

### Size siblings by the same mechanism

Two controls that should be the same height must be sized the same way. One
sized by padding and one by a minimum height can only ever *coincide* — and
they stop coinciding the moment either one's padding changes.

Declare it: both `h-12`. Matching by accident is not matching.

### Containers assign meaning

Anything inside a bordered, tinted, single-hover-target panel is read as part
of that panel's purpose. Put a view count inside a box holding a price and a
Buy button and people read it as something they are being charged for.

**Before adding an element, ask what its container already claims.** If the
answer is wrong, the element belongs outside the container, not restyled
within it.

### Width follows content, not availability

Two short fields stretched to full width because the row was there, while the
thing that belonged beside them sat alone underneath. A field's width should
suggest the length of what goes in it: a name is short, a description is long,
and a full-width name field silently promises otherwise.

### Labels vary; inputs must not

Labels wrap. A two-line label above an input pushes that input a line below its
neighbour, and the row breaks. Make each field a flex column with the input
pinned to the bottom (`h-full flex-col` + `mt-auto`), so every input in a row
sits on one line whatever its label does.

Do not solve it by shortening the label — the next long label reintroduces it.

### Numbers in a column are right-aligned and fixed-width

`0` and `1,240` starting at different left edges makes a column look broken
even when every figure is correct. Right-align, fix the width, use tabular
figures. This is the cheapest credibility in an interface that shows numbers.

---

## 3. Spacing

**One scale, no exceptions.** 4 / 8 / 12 / 16 / 24 / 32 / 48 / 64. A gap that
is not on it is a gap somebody guessed.

**Space belongs to relationships, not elements.** Related things sit closer
than unrelated things — that proximity is the only grouping signal that works
without a border. If you are reaching for a divider, first check whether the
spacing already says it.

**Padding is symmetric unless asymmetry means something.** `pl-3 pr-2` is
almost always a mistake somebody stopped noticing.

**A sticky element changes the spacing of what it sits over.** A page ending in
generous bottom padding, under a sticky bar, under a footer, produces a dead
band nobody designed. When something sticks, the space beneath it is its
responsibility, not the page's.

---

## 4. Responsive

### Design the narrow case first

Not because mobile matters more, but because the narrow case forces the
priority question — what is this row FOR — and the answer improves the wide
case too.

### Dropping is a decision, and it is about width, not importance

On a 375px row, an avatar and a held-time clock cost ~163px, and the name
truncates to "Meridia…" to pay for it. The name is the row. Both get dropped.

State the trade in a comment where the drop happens: what was removed, what it
bought, why the remaining thing won. Otherwise somebody restores it in six
months and the name truncates again.

### Fold economy

Count what sits above the primary content on a phone. Six facts and two
progress bars above a leaderboard means the thing people came for starts below
the fold.

Rule: **one headline, one primary action, at most two supporting facts.**
Everything else folds behind a tap, or moves below the content.

### A breakpoint above the common laptop is effectively "off"

`hidden 2xl:block` (1536px) means most laptops never render it. Something built
and invisible is worse than something missing — it reads as built.

**Verify at the width people actually use**, not the width you have.

---

## 5. Mobile hard rules

- **Inputs at 16px** or iOS zooms on focus and never zooms back. Enforce it
  unlayered, and see §6.
- **Standalone tap targets ≥ 44px.** Links inside a sentence are exempt —
  boxing prose links breaks the paragraph.
- **Nothing scrolls horizontally.** Wide content (tables, tickers, code)
  scrolls inside its own container, never the page.
- **Sticky bottom bars pad with `env(safe-area-inset-bottom)`**, and the
  viewport must be set to `cover` or that inset is always zero.

---

## 6. The traps

**Layered `!important` beats unlayered `!important`.** In Tailwind v4, an
`!important` inside `@layer utilities` wins against an unlayered one. So a
theme override written as unlayered `!important` silently loses.

Use plain unlayered rules: unlayered beats layered regardless of specificity,
and needs no `!important` at all.

**Framework state loses to background re-renders.** A scroll-driven UI flag in
component state is reset by any router refresh or polling revalidation. Put the
flag on the document root and key the CSS off it — outside the framework,
nothing the framework does can undo it.

**Grepping rendered HTML for a label misses it.** React inserts comment nodes
between a literal and an interpolated value, so `held 3d` is `held <!-- -->3d`.
Match on a class or an attribute instead.

**Same number, different meaning by context.** "0 views" on a leaderboard row
reads as a verdict on the person; on their own profile it reads as the honest
state of a new page. Decide per context whether zero is information or an
accusation.

---

## 7. Review checklist

Run before calling a component done:

- [ ] Does it hold up in greyscale?
- [ ] One alignment per row, exceptions declared?
- [ ] Do siblings that match, match **by declaration**?
- [ ] Is every gap on the scale?
- [ ] Do numbers line up down their column?
- [ ] Does each element's container claim what the element means?
- [ ] Does it survive the longest realistic label, name and number?
- [ ] Checked at 375px, 768px, 1280px — and 1440px, not just your own screen?
- [ ] Does any tap target fall under 44px?
- [ ] Any horizontal scroll at 375px?

**And the one that catches most of it:** open the real page at the real width.
Verifying that the code renders is not verifying that a person can see it.