Common Responsive Layout Patterns in CSS

/* Sidebar Layout */
.layout {
  display: flex;
  flex-direction: column;
}

.sidebar {
  background: #f5f5f5;
  padding: 1rem;
}

.main-content {
  flex: 1;
  padding: 1rem;
}

@media (min-width: 768px) {
  .layout {
    flex-direction: row;
  }
  
  .sidebar {
    width: 250px;
    flex-shrink: 0;
  }
}