You don't need design skill to make something that looks competent. You need to stop doing the handful of things that make interfaces look amateur.

1. Space is the whole thing

The single biggest difference between amateur and professional interfaces is whitespace. Not decoration — space.

Pick a spacing scale and use only those values: 4, 8, 12, 16, 24, 32, 48, 64. Never 13 or 27. Consistent spacing looks deliberate; arbitrary spacing looks accidental, even when nobody can say why.

Related things go close together. Unrelated things go far apart. That one rule does most of the work of visual hierarchy.

2. Fewer sizes, fewer weights

Three text sizes and two weights is enough for most interfaces. Every additional one dilutes the hierarchy. If everything is emphasised, nothing is.

3. One accent colour

A neutral palette — greys, or a very desaturated tint — plus one accent for actions. That's it. The accent means "this is the thing to click". Using it for decoration destroys its meaning.

Semantic colours for states: red for destructive, green for success. Never rely on colour alone to convey meaning.

4. Line length and line height

Body text at 60–75 characters per line, with line height around 1.5–1.6. Full-width text on a wide screen is genuinely hard to read, and it's the most common typography mistake on the web.

5. Align things

Pick a left edge and stick to it. Most amateurish layouts are caused by things not lining up, and fixing alignment is free.

6. Steal the structure

design-pass.txt
Here's my interface: <paste>

Improve it using only these levers — no new libraries, no redesign:
- A consistent spacing scale. Show me the values you chose.
- At most three text sizes and two weights.
- One accent colour, used only for actions.
- Body text at a readable measure and line height.
- Consistent alignment.

For each change, one line on what it fixes. Don't add decoration —
I want it clearer, not fancier.

Squint at your screen. What stands out should be what matters. If your least important element is the most visually prominent, that's the bug.