CSS الحديث: التخطيط، المتغيرات، واستعلامات الحاوية (Container Queries)

/* Navigation bar: items in a row */
.nav {
  display: flex;
  gap: 1rem;
  justify-content: space-between; /* Space between nav items and logo */
  align-items: center; /* Vertically centered */
}

/* Form: items in a column */
.form {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

/* Responsive: row on desktop, column on mobile */
@media (max-width: 768px) {
  .nav {
    flex-direction: column;
  }
}

/* Dashboard layout */
.dashboard {
  display: grid;
  grid-template-columns: 250px 1fr 300px; /* Sidebar, main, aside */
  grid-template-rows: auto 1fr auto; /* Header, content, footer */
  gap: 1rem;
  height: 100vh;
}

.header {
  grid-column: 1 / -1; /* Span all columns */
}

.sidebar {
  grid-column: 1;
  grid-row: 2;
}

.main {
  grid-column: 2;
  grid-row: 2;
}

.footer {
  grid-column: 1 / -1;
}

.dashboard {
  display: grid;
  grid-template-columns: 250px 1fr;
}

.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 1rem;
}

.card {
  display: flex;
  flex-direction: column;
}

:root {
  --color-primary: #0066ff;
  --color-text: #333;
  --spacing-base: 1rem;
  --radius: 0.5rem;
}

button {
  background: var(--color-primary);
  padding: var(--spacing-base);
  border-radius: var(--radius);
  color: white;
}

/* Light theme (default) */
:root {
  --bg: #ffffff;
  --text: #000000;
}

/* Dark theme */
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #1a1a1a;
    --text: #ffffff;
  }
}

/* User-selected dark mode */
body.dark-mode {
  --bg: #1a1a1a;
  --text: #ffffff;
}

body {
  background: var(--bg);
  color: var(--text);
}

.card {
  --card-bg: #f5f5f5;
  --card-padding: 1.5rem;
}

.card-header {
  background: var(--card-bg);
  padding: var(--card-padding);
}

/* Different card style */
.card.featured {
  --card-bg: #ffd700;
  --card-padding: 2rem;
  /* Header automatically uses new values */
}

/* Define a container context */
.card-container {
  container-type: inline-size;
}

/* Query the container's width */
@container (min-width: 400px) {
  .card-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
  }
}

@container (max-width: 300px) {
  .card-content {
    display: block;
  }
}

/* Select card if it contains an image */
.card:has(img) {
  display: grid;
  grid-template-columns: 200px 1fr;
}

/* Select form if it has an error */
.form:has(.error) {
  border: 2px solid red;
}

/* Select heading followed by text */
h2:has(+ p) {
  margin-bottom: 0.5rem;
}

/* Style based on input state */
form:has(input:invalid) {
  background: #ffe0e0;
}

/* Dark mode: if user prefers dark, select background */
@media (prefers-color-scheme: dark) {
  body:has(.dark-mode-toggle:checked) {
    --bg: #1a1a1a;
  }
}

/* Define layer order */
@layer reset, base, theme, components, utilities;

@layer reset {
  * { margin: 0; padding: 0; }
}

@layer base {
  body { font-family: system-ui; }
}

@layer theme {
  :root {
    --color-primary: blue;
  }
}

@layer components {
  .button { background: var(--color-primary); }
}

@layer utilities {
  .text-center { text-align: center; }
}

/* Utilities override components override theme—determined by layer order */

/* Before: repetition */
.card { border: 1px solid #ccc; }
.card-header { background: #f5f5f5; }
.card-body { padding: 1rem; }

/* After: native nesting */
.card {
  border: 1px solid #ccc;

  & .header {
    background: #f5f5f5;
  }

  & .body {
    padding: 1rem;
  }

  /* Hover state */
  &:hover {
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
  }

  /* Media query inside */
  @media (max-width: 600px) {
    flex-direction: column;
  }
}

.modal {
  view-transition-name: modal;
}

@supports (view-transition-name: modal) {
  ::view-transition-new(modal) {
    animation: slideUp 0.5s;
  }

  @keyframes slideUp {
    from {
      opacity: 0;
      transform: translateY(50px);
    }
  }
}

document.startViewTransition(() => {
  updateDOM(); // Change the DOM
  // Browser automatically animates the transition
});

<div className="grid grid-cols-1 md:grid-cols-2 gap-4 p-4">
  <div className="border rounded-lg p-4 hover:shadow-lg">
    <h3 className="text-lg font-bold mb-2">Title</h3>
    <p>Content</p>
  </div>
</div>

<div className="card-grid">
  <article className="card">
    <h3>Title</h3>
    <p>Content</p>
  </article>
</div>

<style>
  .card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1rem;
    padding: 1rem;
  }

  .card {
    border: 1px solid #ccc;
    border-radius: 0.5rem;
    padding: 1rem;

    &:hover {
      box-shadow: 0 4px 8px rgba(0,0,0,0.1);
    }
  }
</style>

.toast {
  opacity: 1;
  transform: translateX(0);
  transition: opacity 0.3s, transform 0.3s;
}

/* The "from" state — applied only on first render */
@starting-style {
  .toast {
    opacity: 0;
    transform: translateX(-100%);
  }
}