designing-layouts

Layout Systems & Responsive Design

Purpose

This skill provides comprehensive guidance for creating responsive layout systems using modern CSS techniques. It covers grid systems, flexbox patterns, container queries, spacing systems, and mobile-first design strategies to build flexible, accessible interfaces that adapt seamlessly across devices.

When to Use

Invoke this skill when:

• Building responsive admin dashboards with sidebars and headers
• Creating grid-based layouts for content cards or galleries
• Implementing masonry or Pinterest-style layouts
• Designing split-pane interfaces with resizable panels
• Establishing responsive breakpoint systems
• Structuring application shells with navigation and content areas
• Building mobile-first responsive designs
• Creating flexible spacing and container systems

Layout Patterns

Grid Systems

For structured, two-dimensional layouts, use CSS Grid with design tokens.

12-Column Grid:

.grid-container {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  gap: var(--grid-gap);
  max-width: var(--container-max-width);
  margin: 0 auto;
  padding: 0 var(--container-padding-x);
}

.col-span-6 { grid-column: span 6; }
.col-span-4 { grid-column: span 4; }
.col-span-3 { grid-column: span 3; }

Auto-Fit Responsive Grid:

.auto-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(280px, 100%), 1fr));
  gap: var(--grid-gap);
}

For complex grid layouts and advanced patterns, see references/layout-patterns.md.

Flexbox Patterns

For one-dimensional layouts and alignment control.

Holy Grail Layout:

.holy-grail {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

.holy-grail__body {
  flex: 1;
  display: flex;
}

.holy-grail__nav {
  width: var(--sidebar-width);
  flex-shrink: 0;
}

.holy-grail__main {
  flex: 1;
  min-width: 0; /* Prevent overflow */
}

.holy-grail__aside {
  width: var(--sidebar-width);
  flex-shrink: 0;
}