14 Design Mistakes Developers Make (and How to Fix Them With Examples)

Source: Dev.to

Using Too Many Font Sizes

Problem: Random font sizes make the UI feel messy and unplanned.

/* ❌ What devs often do */
h1 { font-size: 42px; }
h2 { font-size: 30px; }
h3 { font-size: 27px; }
p  { font-size: 18px; }
.small { font-size: 15px; }
.tiny { font-size: 13px; }

How to Fix: Use a consistent scale and repeat it everywhere.

h1 { font-size: 2rem; }
h2 { font-size: 1.5rem; }
h3 { font-size: 1.25rem; }
p  { font-size: 1rem; }

No Spacing System

Problem: Everything feels cramped or uneven.

Fix: Adopt a spacing scale (e.g., 4px → 8px → 12px → 16px → 24px → 32px → 48px) and apply it consistently.

.section {
  padding: 24px;
  margin-bottom: 32px;
}

Inconsistent Buttons

Problem: Different borders, shadows, and padding make buttons look unprofessional.

Fix: Define a single button ruleset and reuse it.

button {
  padding: 10px 16px;
  border-radius: 8px;
  font-weight: 600;
  transition: 0.2s;
}
button:hover { opacity: .9; }
button:active { transform: scale(.97); }

Using Too Many Colors

Problem: More colors do not equal a better UI.

Guideline: Limit the palette to five core colors:

1. Primary
2. Secondary
3. Background
4. Text
5. Accent

Ignoring Hierarchy

Problem: Users don’t know what to look at first.

Fix: Structure content with clear visual hierarchy.

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• Big title → primary message
• Subtitle → supporting context
• Normal text → details

Centering Everything

Problem: Centered paragraphs are hard to read.

Fix:

• Center headings and hero text.
• Left‑align body paragraphs.

Low Contrast Text

Problem: Light grey text looks pretty but is unreadable.

/* ❌ Bad */
color: #999;

/* ✅ Good */
color: #1a1a1a;

Inconsistent Icon Styles

Problem: Mixing icon libraries looks amateur.

Fix: Choose a single icon set (e.g., Lucide, HeroIcons, Feather) and stick with it.

Full‑Width Text

Problem: Wide paragraphs tire the eyes.

Fix: Constrain line length.

max-width: 65ch;

No Visual Grouping

Problem: Elements float without structure.

Fix: Use visual grouping techniques such as:

• Cards
• Background blocks
• Dividers
• Consistent padding and spacing

No Interaction Feedback

Problem: Buttons feel dead.

Fix: Add hover and active states.

button:hover { opacity: .85; }
button:active { transform: scale(.97); }

Popups Everywhere

Problem: Popups are not a reliable navigation strategy.

Fix: Prefer inline components for contextual interactions.

Only Using Color for Errors

Problem: Relying solely on color is not accessible for color‑blind users.

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Not Testing Mobile‑First

Problem: Designs that work on desktop may be unusable on mobile.

Fix: Build with a mobile‑first approach.

.container { width: 100%; }

@media (min-width: 768px) {
  .container {
    max-width: 700px;
    margin: auto;
  }
}

Final Thoughts

You don’t need to “be a designer.” What you need are clear rules and a decision‑making mindset.

• Rules: Consistency, hierarchy, accessibility, and responsiveness.
• Design: Not decoration, but purposeful choices.