CSS Grid Practice
12-Column Grid System
The 12-column grid is a classic layout system in web development. Here's how to implement it with CSS Grid:
Example
HTML
<style>
.grid-12 {
display: grid;
grid-template-columns: repeat(12, 1fr);
gap: 20px;
}
.g-col-3 { grid-column: span 3; }
.g-col-4 { grid-column: span 4; }
.g-col-6 { grid-column: span 6; }
.g-col-8 { grid-column: span 8; }
.g-col-12 { grid-column: span 12; }
.grid-item {
background: #e8f4f8;
border: 1px solid #3498db;
padding: 16px;
text-align: center;
border-radius: 4px;
}
</style>
<div class="grid-12">
<div class="grid-item g-col-3">3 columns</div>
<div class="grid-item g-col-3">3 columns</div>
<div class="grid-item g-col-3">3 columns</div>
<div class="grid-item g-col-3">3 columns</div>
</div>
Common Layout Patterns
Holy Grail Layout
The most common page layout pattern:
Example
HTML
<style>
.holy-grail {
display: grid;
grid-template-areas:
"header header header"
"sidebar main aside"
"footer footer footer";
grid-template-columns: 200px 1fr 200px;
grid-template-rows: 60px 1fr 40px;
min-height: 100vh;
gap: 10px;
}
.hg-header { grid-area: header; background: #2c3e50; color: white; }
.hg-sidebar { grid-area: sidebar; background: #34495e; color: white; }
.hg-main { grid-area: main; background: #ecf0f1; }
.hg-aside { grid-area: aside; background: #34495e; color: white; }
.hg-footer { grid-area: footer; background: #2c3e50; color: white; }
.holy-grail > * { padding: 20px; display: flex; align-items: center; justify-content: center; }
</style>
<div class="holy-grail">
<header class="hg-header">Header</header>
<aside class="hg-sidebar">Sidebar</aside>
<main class="hg-main">Main Content</main>
<aside class="hg-aside">Aside</aside>
<footer class="hg-footer">Footer</footer>
</div>
Responsive Card Grid
Example
HTML
<style>
.card-grid {
display: grid;
grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
gap: 20px;
padding: 20px;
}
.card {
background: white;
border-radius: 8px;
box-shadow: 0 2px 8px rgba(0,0,0,0.1);
padding: 20px;
}
</style>
<div class="card-grid">
<div class="card">Card 1</div>
<div class="card">Card 2</div>
<div class="card">Card 3</div>
<div class="card">Card 4</div>
</div>
❓ FAQ
Q Why do grid systems use 12 columns?
A 12 is divisible by 2, 3, 4, and 6 — maximum flexibility. You can create 1/2, 1/3, 1/4, 1/6, 2/3, 3/4 proportions. Bootstrap and other frameworks use 12-column grids — it's the industry standard.
Q Hand-written grid vs Bootstrap grid?
A Hand-writing helps you understand the principles; Bootstrap is a packaged implementation. Real projects use Bootstrap for efficiency, but understanding principles helps when frameworks don't meet specific needs.
Q Flex grid vs Grid grid — which is better?
A Each has strengths. Flex suits one-dimensional arrangements but can't align across rows. Grid has stronger two-dimensional capabilities. For simple row distribution, Flex is enough; for grid-line alignment, use Grid.
📖 Summary
- Grid systems are a time-tested classic layout solution
- Implementing a 12-column grid with Flexbox isn't complex — key is understanding percentage widths and flex-wrap
- 12 columns offer flexible combinations with responsive breakpoints
- While many projects use Bootstrap or Tailwind grids, implementing once yourself truly teaches the underlying principles
📝 Exercises
- Implement a complete 12-column grid system, create an HTML page showing different column combinations (3-3-3-3, 4-4-4, 2-8-2, etc.).
- Use responsive grid to show single column on mobile, two on tablet, four on desktop.
- Use
col-offset-3to center a content block on the page. - Re-implement the 12-column grid using Grid, compare code differences.