Glassmorphism Design Spec

4 Core Elements

1. Transparency — Semi-transparent backgrounds using rgba() or hsla() with alpha 0.05–0.4
2. Blur — backdrop-filter: blur() ranging 8–40px for frosted-glass effect
3. Border — Subtle semi-transparent borders (1px solid rgba(255,255,255,0.18)) to define edges
4. Shadow — Soft layered box-shadow for depth separation from background

CSS Tokens

Reference: references/tokens.css

Use CSS custom properties from tokens.css for consistent theming:

@import 'references/tokens.css';

.glass-card {
  background: var(--glass-bg);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border: var(--glass-border);
  border-radius: var(--glass-radius);
  box-shadow: var(--glass-shadow);
}

Component Examples

Card

.glass-card {
  background: var(--glass-bg);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border: var(--glass-border);
  border-radius: var(--glass-radius);
  box-shadow: var(--glass-shadow);
  padding: 1.5rem;
}

Navbar

.glass-nav {
  background: var(--glass-bg-heavy);
  backdrop-filter: var(--glass-blur-strong);
  -webkit-backdrop-filter: var(--glass-blur-strong);
  border-bottom: var(--glass-border);
  box-shadow: var(--glass-shadow);
  position: sticky;
  top: 0;
  z-index: 100;
}

Modal Overlay

.glass-modal-backdrop {
  background: rgba(0, 0, 0, 0.4);
  backdrop-filter: blur(4px);
}
.glass-modal {
  background: var(--glass-bg-heavy);
  backdrop-filter: var(--glass-blur-strong);
  -webkit-backdrop-filter: var(--glass-blur-strong);
  border: var(--glass-border);
  border-radius: var(--glass-radius-lg);
  box-shadow: var(--glass-shadow-elevated);
}

Button

.glass-btn {
  background: var(--glass-bg-light);
  backdrop-filter: var(--glass-blur-light);
  -webkit-backdrop-filter: var(--glass-blur-light);
  border: var(--glass-border);
  border-radius: var(--glass-radius);
  transition: background 0.2s;
}
.glass-btn:hover {
  background: var(--glass-bg);
}

Browser Compatibility

Feature	Chrome	Firefox	Safari	Edge
backdrop-filter	76+	103+	9+ (-webkit-)	79+
rgba() backgrounds	All	All	All	All

• Always include -webkit-backdrop-filter for Safari support
• Firefox <103: use @supports fallback with solid semi-transparent bg
• Fallback pattern:

.glass-card {
  background: rgba(255, 255, 255, 0.85); /* fallback */
}
@supports (backdrop-filter: blur(1px)) {
  .glass-card {
    background: var(--glass-bg);
    backdrop-filter: var(--glass-blur);
  }
}

Accessibility Notes

• Ensure contrast ratio ≥ 4.5:1 for text over glass surfaces — test against all possible backgrounds
• Provide prefers-reduced-transparency media query to disable blur/transparency for users who need it
• Avoid placing critical text on highly transparent surfaces without a fallback
• Use prefers-contrast: more to increase border opacity and reduce transparency

@media (prefers-reduced-transparency: reduce) {
  .glass-card {
    background: rgba(255, 255, 255, 0.92);
    backdrop-filter: none;
  }
}
@media (prefers-contrast: more) {
  .glass-card {
    background: rgba(255, 255, 255, 0.85);
    border: 1px solid rgba(0, 0, 0, 0.3);
  }
}