Modern CSS Layout: Grid, Flexbox, and Container Queries

Evolution of Layout Approaches

Era	Approach	Issues
Table layout	<table>	Wrong semantics, inflexible
Float layout	float + clearfix	Collapsed height, complexity
Positioning	position: absolute	Out of document flow
Flexbox	display: flex	One-dimensional ✅
CSS Grid	display: grid	Two-dimensional ✅
Container Queries	@container	Component-level responsive ✅

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Flexbox: One-Dimensional Layout

Best for nav bars, tool card rows, button groups—single row or column:

.tool-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
}

.tool-card {
  flex: 1 1 280px; /* grow shrink basis */
  min-width: 0;    /* prevent overflow */
}

Common patterns

/* Center horizontally and vertically */
.center { display: flex; justify-content: center; align-items: center; }

/* Space between ends */
.navbar { display: flex; justify-content: space-between; align-items: center; }

/* Vertical stack */
.sidebar { display: flex; flex-direction: column; gap: 0.5rem; }

ToolsKu’s home page tool grid uses flex-wrap + flex-basis: 280px for adaptive columns.

---

CSS Grid: Two-Dimensional Layout

Best for page shells, category pages—rows and columns together:

.page-layout {
  display: grid;
  grid-template-columns: 240px 1fr;
  grid-template-rows: auto 1fr auto;
  min-height: 100vh;
}

.sidebar  { grid-row: 1 / -1; grid-column: 1; }
.header   { grid-column: 2; }
.main     { grid-column: 2; overflow: auto; }
.footer   { grid-column: 2; }

Auto-fit grid

.tool-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1rem;
}

auto-fill + minmax computes column count automatically—4 columns when wide, 2 when narrow, no media queries needed.

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Container Queries: Component-Level Responsive

Media queries use viewport width; Container Queries use parent container width:

.tool-card-container {
  container-type: inline-size;
}

@container (max-width: 400px) {
  .tool-card {
    flex-direction: column;
    padding: 0.75rem;
  }
  .tool-card .icon { display: none; }
}

@container (min-width: 401px) {
  .tool-card {
    flex-direction: row;
    padding: 1.25rem;
  }
}

Benefit: The same component adapts in a narrow sidebar vs a wide main area without global media queries.

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ToolsKu Layout in Practice

Tool page layout

┌──────────────────────────────────┐
│  Header (flex, space-between)    │
├────────┬─────────────────────────┤
│ Side   │  Tool Area (grid)       │
│ nav    │  ┌─────┐ ┌─────┐      │
│ (grid  │  │Input│ │Output│      │
│  1fr)  │  └─────┘ └─────┘      │
│        │  ┌─────────────────┐  │
│        │  │   Action Bar    │  │
│        │  └─────────────────┘  │
├────────┴─────────────────────────┤
│  Footer                          │
└──────────────────────────────────┘

Responsive breakpoints

Breakpoint	Layout change
< 640px	Single column; sidebar becomes drawer
640–1024px	Two-column tool grid
> 1024px	Three-column grid + fixed sidebar

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Handy CSS Tools

• Unit converter: px ↔ rem ↔ em
• Aspect ratio calculator: simplest ratio
• Color contrast: WCAG compliance check

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Summary

Flexbox handles one dimension, Grid handles two, Container Queries handle component-level responsiveness—together they cover modern web layout. ToolsKu’s UI is a practical application of this stack.