ممارسة Grid CSS

<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 أعمدة</div>
  <div class="grid-item g-col-3">3 أعمدة</div>
  <div class="grid-item g-col-3">3 أعمدة</div>
  <div class="grid-item g-col-3">3 أعمدة</div>
</div>

<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">ترويسة</header>
  <aside class="hg-sidebar">شريط جانبي</aside>
  <main class="hg-main">المحتوى الرئيسي</main>
  <aside class="hg-aside">جانبي</aside>
  <footer class="hg-footer">تذييل</footer>
</div>

<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">بطاقة 1</div>
  <div class="card">بطاقة 2</div>
  <div class="card">بطاقة 3</div>
  <div class="card">بطاقة 4</div>
</div>