CSS Pseudo-Classes 🎯

Select and style elements based on their state, position, and interaction using powerful CSS pseudo-classes.

What are Pseudo-Classes?

Pseudo-classes are keywords added to selectors that specify a special state of the selected elements. They allow you to style elements based on user interaction, element position, form states, and more.

🎮 Interactive States

:hover, :active, :focus for user interactions

📊 Structural Selection

:nth-child, :first-child for element position

✅ Form States

:valid, :invalid, :required for form validation

Interactive Pseudo-Classes

Common Interactive States:

:hover - When mouse is over element
:active - When element is being activated/clicked
:focus - When element has keyboard focus
:visited - For links that have been visited
:link - For unvisited links

Interactive Demo

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Interactive Pseudo-Classes Demo</title>
  <style>
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    
    body {
      font-family: 'Inter', sans-serif;
      line-height: 1.6;
      background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
      min-height: 100vh;
      padding: 2rem;
    }
    
    .container {
      max-width: 1200px;
      margin: 0 auto;
      background: white;
      border-radius: 20px;
      padding: 3rem;
      box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
    }
    
    h1 {
      color: #2d3748;
      margin-bottom: 2rem;
      text-align: center;
      font-size: 2.5rem;
    }
    
    .demo-section {
      background: #f8fafc;
      padding: 2rem;
      border-radius: 15px;
      margin: 2rem 0;
      border-left: 4px solid #667eea;
    }
    
    .code-example {
      background: #2d3748;
      color: #81e6d9;
      padding: 1rem;
      border-radius: 8px;
      font-family: monospace;
      margin: 1rem 0;
      font-size: 0.9rem;
    }
    
    /* Interactive Demo Styles */
    .interactive-grid {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
      gap: 2rem;
      margin: 2rem 0;
    }
    
    .demo-item {
      background: white;
      padding: 2rem;
      border-radius: 12px;
      box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
      text-align: center;
      transition: all 0.3s ease;
    }
    
    /* :hover Pseudo-class */
    .hover-demo {
      background: #e3f2fd;
      border: 2px solid #2196f3;
      cursor: pointer;
    }
    
    .hover-demo:hover {
      background: #bbdefb;
      transform: translateY(-5px);
      box-shadow: 0 8px 15px rgba(33, 150, 243, 0.3);
    }
    
    /* :active Pseudo-class */
    .active-demo {
      background: #ffe0b2;
      border: 2px solid #ff9800;
      cursor: pointer;
      user-select: none;
    }
    
    .active-demo:active {
      background: #ffcc80;
      transform: scale(0.95);
    }
    
    /* :focus Pseudo-class */
    .focus-demo {
      background: #e8f5e8;
      border: 2px solid #4caf50;
      padding: 1rem;
      outline: none;
    }
    
    .focus-demo:focus {
      background: #c8e6c9;
      border-color: #2e7d32;
      box-shadow: 0 0 0 3px rgba(76, 175, 80, 0.3);
    }
    
    /* :nth-child Pseudo-class */
    .nth-child-demo {
      display: flex;
      gap: 1rem;
      flex-wrap: wrap;
      justify-content: center;
    }
    
    .nth-child-demo div {
      width: 50px;
      height: 50px;
      background: #f48fb1;
      display: flex;
      align-items: center;
      justify-content: center;
      border-radius: 8px;
      font-weight: bold;
      color: white;
    }
    
    .nth-child-demo div:nth-child(odd) {
      background: #7986cb;
    }
    
    .nth-child-demo div:nth-child(3n) {
      transform: rotate(15deg);
    }
    
    .nth-child-demo div:nth-child(2n+1):hover {
      background: #5c6bc0;
      transform: scale(1.2);
    }
    
    /* :checked Pseudo-class */
    .checkbox-demo {
      display: flex;
      gap: 2rem;
      justify-content: center;
      margin: 1rem 0;
    }
    
    .checkbox-demo input[type="checkbox"] {
      display: none;
    }
    
    .checkbox-demo label {
      padding: 1rem 2rem;
      background: #f5f5f5;
      border-radius: 8px;
      cursor: pointer;
      transition: all 0.3s;
      border: 2px solid #ddd;
    }
    
    .checkbox-demo input[type="checkbox"]:checked + label {
      background: #4caf50;
      color: white;
      border-color: #2e7d32;
      transform: scale(1.05);
    }
    
    /* :not() Pseudo-class */
    .not-demo {
      display: flex;
      gap: 1rem;
      justify-content: center;
      flex-wrap: wrap;
    }
    
    .not-demo button {
      padding: 0.8rem 1.5rem;
      border: none;
      border-radius: 6px;
      background: #2196f3;
      color: white;
      cursor: pointer;
      transition: all 0.3s;
    }
    
    .not-demo button:not(.special) {
      background: #757575;
    }
    
    .not-demo button:hover:not(.special) {
      background: #424242;
    }
    
    .not-demo button.special {
      background: #ff9800;
    }
    
    .not-demo button.special:hover {
      background: #f57c00;
      transform: scale(1.1);
    }
    
    /* First and Last Child */
    .first-last-demo {
      display: flex;
      gap: 1rem;
      justify-content: center;
    }
    
    .first-last-demo p {
      padding: 1rem;
      background: #e1f5fe;
      border-radius: 6px;
      margin: 0.5rem;
    }
    
    .first-last-demo p:first-child {
      background: #b3e5fc;
      font-weight: bold;
    }
    
    .first-last-demo p:last-child {
      background: #81d4fa;
      font-style: italic;
    }
    
    .first-last-demo p:nth-child(2) {
      background: #4fc3f7;
    }
  </style>
</head>
<body>
  <div class="container">
    <h1>🎯 CSS Pseudo-Classes Interactive Demo</h1>
    
    <div class="demo-section">
      <h2>:hover - Mouse Over Effect</h2>
      <div class="code-example">
        .element:hover {<br>
        &nbsp;&nbsp;background: #bbdefb;<br>
        &nbsp;&nbsp;transform: translateY(-5px);<br>
        }
      </div>
      <div class="interactive-grid">
        <div class="demo-item hover-demo">
          <h3>Hover Over Me!</h3>
          <p>Move your mouse over this box to see the :hover effect</p>
        </div>
      </div>
    </div>
    
    <div class="demo-section">
      <h2>:active - Click Effect</h2>
      <div class="code-example">
        .element:active {<br>
        &nbsp;&nbsp;transform: scale(0.95);<br>
        &nbsp;&nbsp;background: #ffcc80;<br>
        }
      </div>
      <div class="interactive-grid">
        <div class="demo-item active-demo">
          <h3>Click and Hold!</h3>
          <p>Click and hold this box to see the :active effect</p>
        </div>
      </div>
    </div>
    
    <div class="demo-section">
      <h2>:focus - Input Focus</h2>
      <div class="code-example">
        input:focus {<br>
        &nbsp;&nbsp;box-shadow: 0 0 0 3px rgba(76, 175, 80, 0.3);<br>
        &nbsp;&nbsp;border-color: #2e7d32;<br>
        }
      </div>
      <div class="interactive-grid">
        <div class="demo-item">
          <h3>Focus on Input</h3>
          <input type="text" class="focus-demo" placeholder="Click here to focus">
          <p style="margin-top: 1rem;">Click the input field to see :focus effect</p>
        </div>
      </div>
    </div>
    
    <div class="demo-section">
      <h2>:nth-child() - Pattern Selection</h2>
      <div class="code-example">
        div:nth-child(odd) { background: #7986cb; }<br>
        div:nth-child(3n) { transform: rotate(15deg); }<br>
        div:nth-child(2n+1):hover { transform: scale(1.2); }
      </div>
      <div class="demo-item">
        <h3>Number Patterns</h3>
        <div class="nth-child-demo">
          <div>1</div><div>2</div><div>3</div><div>4</div><div>5</div>
          <div>6</div><div>7</div><div>8</div><div>9</div><div>10</div>
        </div>
        <p>Odd numbers are blue, every 3rd is rotated, hover effects vary!</p>
      </div>
    </div>
    
    <div class="demo-section">
      <h2>:checked - Toggle States</h2>
      <div class="code-example">
        input[type="checkbox"]:checked + label {<br>
        &nbsp;&nbsp;background: #4caf50;<br>
        &nbsp;&nbsp;transform: scale(1.05);<br>
        }
      </div>
      <div class="demo-item">
        <h3>Toggle These Options</h3>
        <div class="checkbox-demo">
          <input type="checkbox" id="option1">
          <label for="option1">Feature 1</label>
          
          <input type="checkbox" id="option2">
          <label for="option2">Feature 2</label>
          
          <input type="checkbox" id="option3">
          <label for="option3">Feature 3</label>
        </div>
        <p>Click the options to see :checked state changes</p>
      </div>
    </div>
    
    <div class="demo-section">
      <h2>:not() - Exclusion Selector</h2>
      <div class="code-example">
        button:not(.special) { background: #757575; }<br>
        button.special { background: #ff9800; }
      </div>
      <div class="demo-item">
        <h3>All Buttons Except Special</h3>
        <div class="not-demo">
          <button>Normal</button>
          <button>Normal</button>
          <button class="special">Special</button>
          <button>Normal</button>
          <button class="special">Special</button>
        </div>
        <p>The :not() selector excludes elements from being selected</p>
      </div>
    </div>
    
    <div class="demo-section">
      <h2>:first-child, :last-child</h2>
      <div class="code-example">
        p:first-child { background: #b3e5fc; }<br>
        p:last-child { background: #81d4fa; }<br>
        p:nth-child(2) { background: #4fc3f7; }
      </div>
      <div class="demo-item">
        <h3>First and Last Elements</h3>
        <div class="first-last-demo">
          <p>First Child</p>
          <p>Middle Child</p>
          <p>Last Child</p>
        </div>
        <p>Different styles for first, middle, and last elements</p>
      </div>
    </div>
  </div>
</body>
</html>

Form Pseudo-Classes

Validation States

Use pseudo-classes to provide visual feedback for form validation without JavaScript.

input:valid { border-color: green; }

input:invalid { border-color: red; }

input:required { background: yellow; }

Input States

Control how form elements appear in different states like disabled, read-only, or checked.

input:disabled { opacity: 0.6; }

input:checked { background: blue; }

input:focus { outline: blue; }

Form Validation Demo

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Form Pseudo-Classes Demo</title>
  <style>
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    
    body {
      font-family: 'Inter', sans-serif;
      line-height: 1.6;
      background: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
      min-height: 100vh;
      padding: 2rem;
    }
    
    .container {
      max-width: 800px;
      margin: 0 auto;
      background: white;
      border-radius: 20px;
      padding: 3rem;
      box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
    }
    
    h1 {
      color: #2d3748;
      margin-bottom: 2rem;
      text-align: center;
      font-size: 2.5rem;
    }
    
    .form-section {
      background: #f8fafc;
      padding: 2rem;
      border-radius: 15px;
      margin: 2rem 0;
      border-left: 4px solid #4facfe;
    }
    
    .code-example {
      background: #2d3748;
      color: #81e6d9;
      padding: 1rem;
      border-radius: 8px;
      font-family: monospace;
      margin: 1rem 0;
      font-size: 0.9rem;
    }
    
    /* Form Styles */
    .form-group {
      margin-bottom: 1.5rem;
    }
    
    label {
      display: block;
      margin-bottom: 0.5rem;
      font-weight: 600;
      color: #2d3748;
    }
    
    input, select, textarea {
      width: 100%;
      padding: 0.8rem;
      border: 2px solid #e2e8f0;
      border-radius: 8px;
      font-size: 1rem;
      transition: all 0.3s ease;
    }
    
    /* :required and :optional */
    input:required {
      border-left: 4px solid #e53e3e;
      background: #fed7d7;
    }
    
    input:optional {
      border-left: 4px solid #38a169;
      background: #f0fff4;
    }
    
    /* :valid and :invalid */
    input:valid {
      border-color: #38a169;
      background: #f0fff4;
    }
    
    input:invalid {
      border-color: #e53e3e;
      background: #fed7d7;
    }
    
    input:focus:invalid {
      box-shadow: 0 0 0 3px rgba(229, 62, 62, 0.3);
    }
    
    input:focus:valid {
      box-shadow: 0 0 0 3px rgba(56, 161, 105, 0.3);
    }
    
    /* :in-range and :out-of-range */
    input[type="number"]:in-range {
      border-color: #3182ce;
      background: #ebf8ff;
    }
    
    input[type="number"]:out-of-range {
      border-color: #d69e2e;
      background: #fefcbf;
    }
    
    /* :disabled and :enabled */
    input:disabled {
      background: #f7fafc;
      color: #a0aec0;
      cursor: not-allowed;
    }
    
    input:enabled {
      background: white;
    }
    
    /* :read-only and :read-write */
    input:read-only {
      background: #f7fafc;
      color: #718096;
    }
    
    input:read-write {
      background: white;
      color: #2d3748;
    }
    
    /* Checkbox and Radio Styles */
    .checkbox-group, .radio-group {
      display: flex;
      gap: 2rem;
      margin: 1rem 0;
    }
    
    input[type="checkbox"], input[type="radio"] {
      width: auto;
      margin-right: 0.5rem;
    }
    
    /* :checked styles for custom checkboxes */
    .custom-checkbox {
      position: relative;
      padding-left: 2rem;
      cursor: pointer;
    }
    
    .custom-checkbox input {
      display: none;
    }
    
    .custom-checkbox .checkmark {
      position: absolute;
      left: 0;
      top: 0;
      height: 1.2rem;
      width: 1.2rem;
      background: #e2e8f0;
      border-radius: 4px;
      transition: all 0.3s;
    }
    
    .custom-checkbox input:checked + .checkmark {
      background: #4facfe;
    }
    
    .custom-checkbox input:checked + .checkmark::after {
      content: "✓";
      color: white;
      position: absolute;
      left: 50%;
      top: 50%;
      transform: translate(-50%, -50%);
    }
    
    /* Submit Button */
    .submit-btn {
      background: #4facfe;
      color: white;
      padding: 1rem 2rem;
      border: none;
      border-radius: 8px;
      font-size: 1.1rem;
      cursor: pointer;
      transition: all 0.3s;
      width: 100%;
    }
    
    .submit-btn:hover {
      background: #3a8bd6;
      transform: translateY(-2px);
    }
    
    .submit-btn:active {
      transform: translateY(0);
    }
    
    .submit-btn:disabled {
      background: #a0aec0;
      cursor: not-allowed;
      transform: none;
    }
    
    /* Focus styles for accessibility */
    *:focus {
      outline: 2px solid #4facfe;
      outline-offset: 2px;
    }
    
    /* Demo info boxes */
    .demo-info {
      background: #e3f2fd;
      padding: 1rem;
      border-radius: 8px;
      margin: 1rem 0;
      border-left: 4px solid #2196f3;
    }
  </style>
</head>
<body>
  <div class="container">
    <h1>📝 Form Pseudo-Classes Demo</h1>
    
    <div class="form-section">
      <h2>Form Validation States</h2>
      <div class="code-example">
        input:required { border-left: 4px solid red; }<br>
        input:valid { border-color: green; }<br>
        input:invalid { border-color: red; }
      </div>
      
      <form>
        <div class="form-group">
          <label for="email">Email Address *</label>
          <input type="email" id="email" required placeholder="Enter valid email">
          <div class="demo-info">
            <strong>:required</strong> - Red border for required fields<br>
            <strong>:valid/:invalid</strong> - Green/Red based on validation
          </div>
        </div>
        
        <div class="form-group">
          <label for="phone">Phone Number (Optional)</label>
          <input type="tel" id="phone" placeholder="Optional field">
          <div class="demo-info">
            <strong>:optional</strong> - Green border for optional fields
          </div>
        </div>
        
        <div class="form-group">
          <label for="age">Age (10-100)</label>
          <input type="number" id="age" min="10" max="100" value="25" required>
          <div class="demo-info">
            <strong>:in-range/:out-of-range</strong> - Different styles for valid/invalid ranges
          </div>
        </div>
        
        <div class="form-group">
          <label for="username">Username</label>
          <input type="text" id="username" required pattern="[A-Za-z]{3,}">
          <div class="demo-info">
            <strong>pattern attribute</strong> - Uses regex validation with :valid/:invalid
          </div>
        </div>
        
        <div class="form-group">
          <label for="readonly">Read-only Field</label>
          <input type="text" id="readonly" value="This field is read-only" readonly>
          <div class="demo-info">
            <strong>:read-only</strong> - Different styling for non-editable fields
          </div>
        </div>
        
        <div class="form-group">
          <label>Custom Checkboxes</label>
          <div class="checkbox-group">
            <label class="custom-checkbox">
              <input type="checkbox" checked>
              <span class="checkmark"></span>
              Option 1
            </label>
            <label class="custom-checkbox">
              <input type="checkbox">
              <span class="checkmark"></span>
              Option 2
            </label>
          </div>
          <div class="demo-info">
            <strong>:checked</strong> - Custom styles for checked state
          </div>
        </div>
        
        <div class="form-group">
          <label for="disabled">Disabled Field</label>
          <input type="text" id="disabled" value="This field is disabled" disabled>
          <div class="demo-info">
            <strong>:disabled</strong> - Grayed out and non-interactive
          </div>
        </div>
        
        <button type="submit" class="submit-btn">Submit Form</button>
      </form>
    </div>
    
    <div class="form-section">
      <h2>Interactive Demo Instructions</h2>
      <div class="demo-info">
        <p><strong>Try these interactions:</strong></p>
        <ul>
          <li>Enter invalid email to see :invalid state</li>
          <li>Enter valid email to see :valid state</li>
          <li>Type less than 3 characters in username</li>
          <li>Enter age outside 10-100 range</li>
          <li>Click checkboxes to see :checked state</li>
          <li>Try focusing on different fields</li>
        </ul>
      </div>
    </div>
  </div>
</body>
</html>

Advanced Pseudo-Classes

Structural & URL-based Selection

Advanced pseudo-classes allow selection based on element position, content, and even URL fragments.

/* URL fragment targeting */

section:target { background: yellow; }

/* Empty elements */

div:empty { display: none; }

/* Language specific */

p:lang(fr) { font-style: italic; }

Advanced Techniques Demo

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Advanced Pseudo-Classes Demo</title>
  <style>
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    
    body {
      font-family: 'Inter', sans-serif;
      line-height: 1.6;
      background: linear-gradient(135deg, #ff9a9e 0%, #fecfef 100%);
      min-height: 100vh;
      padding: 2rem;
    }
    
    .container {
      max-width: 1200px;
      margin: 0 auto;
      background: white;
      border-radius: 20px;
      padding: 3rem;
      box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
    }
    
    h1 {
      color: #2d3748;
      margin-bottom: 2rem;
      text-align: center;
      font-size: 2.5rem;
    }
    
    .demo-section {
      background: #f8fafc;
      padding: 2rem;
      border-radius: 15px;
      margin: 2rem 0;
      border-left: 4px solid #ff9a9e;
    }
    
    .code-example {
      background: #2d3748;
      color: #81e6d9;
      padding: 1rem;
      border-radius: 8px;
      font-family: monospace;
      margin: 1rem 0;
      font-size: 0.9rem;
    }
    
    /* :target Demo */
    .target-demo {
      margin: 2rem 0;
    }
    
    .target-nav {
      display: flex;
      gap: 1rem;
      margin-bottom: 1rem;
    }
    
    .target-nav a {
      padding: 0.5rem 1rem;
      background: #e3f2fd;
      border-radius: 6px;
      text-decoration: none;
      color: #1976d2;
      transition: all 0.3s;
    }
    
    .target-content div {
      padding: 2rem;
      margin: 1rem 0;
      background: white;
      border-radius: 8px;
      border: 2px solid transparent;
      display: none;
    }
    
    .target-content div:target {
      display: block;
      border-color: #1976d2;
      background: #e3f2fd;
      animation: fadeIn 0.5s ease;
    }
    
    @keyframes fadeIn {
      from { opacity: 0; transform: translateY(10px); }
      to { opacity: 1; transform: translateY(0); }
    }
    
    /* :empty Demo */
    .empty-demo {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
      gap: 1rem;
      margin: 1rem 0;
    }
    
    .empty-box {
      padding: 2rem;
      background: #f5f5f5;
      border-radius: 8px;
      text-align: center;
      min-height: 100px;
      border: 2px solid #ddd;
    }
    
    .empty-box:empty {
      background: #ffebee;
      border-color: #f44336;
      position: relative;
    }
    
    .empty-box:empty::after {
      content: "Empty!";
      color: #f44336;
      font-style: italic;
    }
    
    /* :lang() Demo */
    .lang-demo {
      margin: 2rem 0;
    }
    
    .lang-demo p:lang(en) {
      background: #e3f2fd;
      padding: 1rem;
      border-left: 4px solid #2196f3;
    }
    
    .lang-demo p:lang(es) {
      background: #e8f5e8;
      padding: 1rem;
      border-left: 4px solid #4caf50;
    }
    
    .lang-demo p:lang(fr) {
      background: #f3e5f5;
      padding: 1rem;
      border-left: 4px solid #9c27b0;
    }
    
    /* Structural Pseudo-classes */
    .structural-demo {
      display: flex;
      gap: 1rem;
      flex-wrap: wrap;
      justify-content: center;
      margin: 2rem 0;
    }
    
    .structural-demo div {
      padding: 1rem;
      background: #f5f5f5;
      border-radius: 6px;
      min-width: 80px;
      text-align: center;
    }
    
    .structural-demo div:first-of-type {
      background: #bbdefb;
      font-weight: bold;
    }
    
    .structural-demo div:last-of-type {
      background: #c8e6c9;
      font-style: italic;
    }
    
    .structural-demo div:nth-of-type(3n) {
      transform: rotate(-5deg);
    }
    
    /* :root Demo */
    :root {
      --primary-color: #ff6b6b;
      --secondary-color: #4ecdc4;
      --spacing: 1rem;
    }
    
    .root-demo {
      background: var(--primary-color);
      color: white;
      padding: var(--spacing);
      border-radius: 8px;
      margin: 1rem 0;
    }
    
    .root-demo:nth-child(even) {
      background: var(--secondary-color);
    }
    
    /* Interactive Elements */
    .interactive-demo {
      margin: 2rem 0;
    }
    
    .interactive-grid {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
      gap: 1rem;
    }
    
    .interactive-item {
      padding: 1.5rem;
      background: white;
      border-radius: 8px;
      border: 2px solid #e0e0e0;
      transition: all 0.3s;
      cursor: pointer;
    }
    
    .interactive-item:hover {
      border-color: var(--primary-color);
      transform: translateY(-2px);
    }
    
    .interactive-item:active {
      transform: translateY(0);
    }
    
    /* Demo Controls */
    .demo-controls {
      background: #fff3e0;
      padding: 1rem;
      border-radius: 8px;
      margin: 1rem 0;
      border-left: 4px solid #ff9800;
    }
  </style>
</head>
<body>
  <div class="container">
    <h1>🚀 Advanced Pseudo-Classes Demo</h1>
    
    <div class="demo-section">
      <h2>:target - URL Fragment Navigation</h2>
      <div class="code-example">
        div:target {<br>
        &nbsp;&nbsp;display: block;<br>
        &nbsp;&nbsp;border-color: #1976d2;<br>
        &nbsp;&nbsp;animation: fadeIn 0.5s ease;<br>
        }
      </div>
      
      <div class="target-demo">
        <div class="target-nav">
          <a href="#tab1">Tab 1</a>
          <a href="#tab2">Tab 2</a>
          <a href="#tab3">Tab 3</a>
        </div>
        
        <div class="target-content">
          <div id="tab1">
            <h3>Tab 1 Content</h3>
            <p>This content is shown because #tab1 is in the URL</p>
          </div>
          <div id="tab2">
            <h3>Tab 2 Content</h3>
            <p>Click the tabs above to change the URL fragment</p>
          </div>
          <div id="tab3">
            <h3>Tab 3 Content</h3>
            <p>:target selects the element with ID matching URL fragment</p>
          </div>
        </div>
      </div>
    </div>
    
    <div class="demo-section">
      <h2>:empty - Empty Element Detection</h2>
      <div class="code-example">
        .element:empty {<br>
        &nbsp;&nbsp;background: #ffebee;<br>
        &nbsp;&nbsp;border-color: #f44336;<br>
        }<br>
        .element:empty::after {<br>
        &nbsp;&nbsp;content: "Empty!";<br>
        }
      </div>
      
      <div class="empty-demo">
        <div class="empty-box">I have content</div>
        <div class="empty-box"></div>
        <div class="empty-box">Another box with text</div>
        <div class="empty-box"><!-- This comment doesn't count as content --></div>
      </div>
      <p>:empty selects elements with no children (including text nodes)</p>
    </div>
    
    <div class="demo-section">
      <h2>:lang() - Language Specific Styles</h2>
      <div class="code-example">
        p:lang(en) { background: #e3f2fd; }<br>
        p:lang(es) { background: #e8f5e8; }<br>
        p:lang(fr) { background: #f3e5f5; }
      </div>
      
      <div class="lang-demo">
        <p lang="en">This is an English paragraph with specific styling.</p>
        <p lang="es">Este es un párrafo en español con estilo específico.</p>
        <p lang="fr">Ceci est un paragraphe en français avec un style spécifique.</p>
      </div>
    </div>
    
    <div class="demo-section">
      <h2>Structural Pseudo-classes</h2>
      <div class="code-example">
        div:first-of-type { background: #bbdefb; }<br>
        div:last-of-type { background: #c8e6c9; }<br>
        div:nth-of-type(3n) { transform: rotate(-5deg); }
      </div>
      
      <div class="structural-demo">
        <div>First</div>
        <div>Second</div>
        <div>Third</div>
        <div>Fourth</div>
        <div>Fifth</div>
        <div>Sixth</div>
        <div>Seventh</div>
        <div>Eighth</div>
      </div>
    </div>
    
    <div class="demo-section">
      <h2>:root - CSS Variables Scope</h2>
      <div class="code-example">
        :root {<br>
        &nbsp;&nbsp;--primary-color: #ff6b6b;<br>
        &nbsp;&nbsp;--secondary-color: #4ecdc4;<br>
        &nbsp;&nbsp;--spacing: 1rem;<br>
        }<br><br>
        .element {<br>
        &nbsp;&nbsp;background: var(--primary-color);<br>
        &nbsp;&nbsp;padding: var(--spacing);<br>
        }
      </div>
      
      <div class="root-demo">Primary Color from :root</div>
      <div class="root-demo">Secondary Color (even child)</div>
      <div class="root-demo">Primary Color again</div>
    </div>
    
    <div class="demo-controls">
      <h3>💡 Pro Tips</h3>
      <ul>
        <li>Use :target for single-page applications without JavaScript</li>
        <li>:empty is great for dynamic content that might be empty</li>
        <li>:lang() helps with internationalization and accessibility</li>
        <li>Structural pseudo-classes work based on element type</li>
        <li>:root is perfect for CSS custom properties (variables)</li>
      </ul>
    </div>
  </div>
</body>
</html>

Practical Real-World Examples

📋 Navigation Menus

Interactive nav states with hover and active effects

📊 Data Tables

Zebra striping and row hover effects

✅ Form Validation

Real-time validation feedback

Practical Implementation

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Practical Pseudo-Classes Examples</title>
  <style>
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    
    body {
      font-family: 'Inter', sans-serif;
      line-height: 1.6;
      background: linear-gradient(135deg, #a8edea 0%, #fed6e3 100%);
      min-height: 100vh;
      padding: 2rem;
    }
    
    .container {
      max-width: 1400px;
      margin: 0 auto;
    }
    
    h1 {
      color: #2d3748;
      margin-bottom: 2rem;
      text-align: center;
      font-size: 2.5rem;
    }
    
    /* Navigation Menu */
    .nav-menu {
      background: white;
      border-radius: 15px;
      padding: 2rem;
      margin: 2rem 0;
      box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
    }
    
    .nav-list {
      list-style: none;
      display: flex;
      gap: 0;
      background: #f8fafc;
      border-radius: 10px;
      overflow: hidden;
    }
    
    .nav-list li {
      flex: 1;
    }
    
    .nav-list a {
      display: block;
      padding: 1rem 2rem;
      text-decoration: none;
      color: #4a5568;
      text-align: center;
      transition: all 0.3s;
      border-bottom: 3px solid transparent;
    }
    
    .nav-list a:hover {
      background: #e2e8f0;
      color: #2d3748;
    }
    
    .nav-list a:active {
      background: #cbd5e0;
      transform: scale(0.98);
    }
    
    .nav-list a:focus {
      outline: 2px solid #667eea;
      outline-offset: -2px;
    }
    
    /* Current page indicator */
    .nav-list a[aria-current="page"] {
      background: #667eea;
      color: white;
      border-bottom-color: #4c51bf;
    }
    
    /* Table Styles */
    .data-table {
      width: 100%;
      background: white;
      border-radius: 15px;
      overflow: hidden;
      box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
      margin: 2rem 0;
    }
    
    .data-table table {
      width: 100%;
      border-collapse: collapse;
    }
    
    .data-table th {
      background: #667eea;
      color: white;
      padding: 1rem;
      text-align: left;
    }
    
    .data-table td {
      padding: 1rem;
      border-bottom: 1px solid #e2e8f0;
    }
    
    .data-table tr:nth-child(even) {
      background: #f8fafc;
    }
    
    .data-table tr:hover {
      background: #e2e8f0;
      transform: scale(1.01);
      transition: all 0.2s;
    }
    
    .data-table tr:last-child td {
      border-bottom: none;
    }
    
    /* Card Grid */
    .card-grid {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
      gap: 2rem;
      margin: 2rem 0;
    }
    
    .card {
      background: white;
      border-radius: 15px;
      padding: 2rem;
      box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
      transition: all 0.3s;
      border: 2px solid transparent;
    }
    
    .card:hover {
      transform: translateY(-5px);
      box-shadow: 0 20px 40px rgba(0, 0, 0, 0.15);
      border-color: #667eea;
    }
    
    .card:active {
      transform: translateY(-2px);
    }
    
    .card:nth-child(3n+1) {
      border-left: 4px solid #667eea;
    }
    
    .card:nth-child(3n+2) {
      border-left: 4px solid #4ecdc4;
    }
    
    .card:nth-child(3n+3) {
      border-left: 4px solid #ff6b6b;
    }
    
    /* Button Group */
    .button-group {
      display: flex;
      gap: 1rem;
      margin: 2rem 0;
      flex-wrap: wrap;
    }
    
    .btn {
      padding: 1rem 2rem;
      border: none;
      border-radius: 8px;
      font-size: 1rem;
      cursor: pointer;
      transition: all 0.3s;
      position: relative;
      overflow: hidden;
    }
    
    .btn-primary {
      background: #667eea;
      color: white;
    }
    
    .btn-primary:hover {
      background: #5a67d8;
      transform: translateY(-2px);
    }
    
    .btn-primary:active {
      transform: translateY(0);
    }
    
    .btn-primary:focus {
      box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.3);
    }
    
    .btn-secondary {
      background: #e2e8f0;
      color: #4a5568;
    }
    
    .btn-secondary:hover:not(:disabled) {
      background: #cbd5e0;
    }
    
    .btn:disabled {
      background: #a0aec0;
      cursor: not-allowed;
      transform: none !important;
    }
    
    /* Form Validation */
    .form-container {
      background: white;
      border-radius: 15px;
      padding: 2rem;
      margin: 2rem 0;
      box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
    }
    
    .form-group {
      margin-bottom: 1.5rem;
    }
    
    .form-group input {
      width: 100%;
      padding: 1rem;
      border: 2px solid #e2e8f0;
      border-radius: 8px;
      font-size: 1rem;
      transition: all 0.3s;
    }
    
    .form-group input:focus {
      border-color: #667eea;
      box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
    }
    
    .form-group input:invalid {
      border-color: #e53e3e;
    }
    
    .form-group input:valid {
      border-color: #38a169;
    }
    
    /* Progress Indicator */
    .progress-steps {
      display: flex;
      margin: 2rem 0;
      background: white;
      border-radius: 15px;
      padding: 2rem;
      box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
    }
    
    .step {
      flex: 1;
      text-align: center;
      padding: 1rem;
      position: relative;
    }
    
    .step:not(:last-child)::after {
      content: '';
      position: absolute;
      top: 50%;
      right: 0;
      width: 50%;
      height: 2px;
      background: #e2e8f0;
      z-index: 1;
    }
    
    .step.active {
      color: #667eea;
      font-weight: bold;
    }
    
    .step.active::before {
      content: '✓';
      background: #667eea;
      color: white;
      width: 30px;
      height: 30px;
      border-radius: 50%;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      margin-bottom: 0.5rem;
    }
    
    .step:not(.active)::before {
      content: counter(step);
      background: #e2e8f0;
      color: #a0aec0;
      width: 30px;
      height: 30px;
      border-radius: 50%;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      margin-bottom: 0.5rem;
    }
    
    .progress-steps {
      counter-reset: step;
    }
    
    .step {
      counter-increment: step;
    }
  </style>
</head>
<body>
  <div class="container">
    <h1>💼 Practical Pseudo-Classes Examples</h1>
    
    <!-- Navigation Menu -->
    <nav class="nav-menu">
      <h2>📋 Navigation Menu with States</h2>
      <ul class="nav-list">
        <li><a href="#" aria-current="page">Dashboard</a></li>
        <li><a href="#">Projects</a></li>
        <li><a href="#">Team</a></li>
        <li><a href="#">Calendar</a></li>
        <li><a href="#">Reports</a></li>
      </ul>
      <p style="margin-top: 1rem; color: #666;">
        Uses: :hover, :active, :focus, and attribute selectors for current page
      </p>
    </nav>
    
    <!-- Data Table -->
    <div class="data-table">
      <h2>📊 Data Table with Zebra Striping</h2>
      <table>
        <thead>
          <tr>
            <th>Name</th>
            <th>Email</th>
            <th>Status</th>
            <th>Actions</th>
          </tr>
        </thead>
        <tbody>
          <tr>
            <td>John Doe</td>
            <td>john@example.com</td>
            <td>Active</td>
            <td>
              <button class="btn btn-primary" style="padding: 0.5rem 1rem; font-size: 0.9rem;">Edit</button>
            </td>
          </tr>
          <tr>
            <td>Jane Smith</td>
            <td>jane@example.com</td>
            <td>Inactive</td>
            <td>
              <button class="btn btn-primary" style="padding: 0.5rem 1rem; font-size: 0.9rem;">Edit</button>
            </td>
          </tr>
          <tr>
            <td>Mike Johnson</td>
            <td>mike@example.com</td>
            <td>Active</td>
            <td>
              <button class="btn btn-primary" style="padding: 0.5rem 1rem; font-size: 0.9rem;">Edit</button>
            </td>
          </tr>
          <tr>
            <td>Sarah Wilson</td>
            <td>sarah@example.com</td>
            <td>Pending</td>
            <td>
              <button class="btn btn-primary" style="padding: 0.5rem 1rem; font-size: 0.9rem;">Edit</button>
            </td>
          </tr>
        </tbody>
      </table>
      <p style="padding: 1rem; color: #666;">
        Uses: :nth-child(even), :hover, :last-child for table styling
      </p>
    </div>
    
    <!-- Card Grid -->
    <div>
      <h2>🎴 Interactive Card Grid</h2>
      <div class="card-grid">
        <div class="card">
          <h3>Web Development</h3>
          <p>Build modern web applications with latest technologies</p>
        </div>
        <div class="card">
          <h3>UI/UX Design</h3>
          <p>Create beautiful and user-friendly interfaces</p>
        </div>
        <div class="card">
          <h3>Mobile Apps</h3>
          <p>Develop cross-platform mobile applications</p>
        </div>
        <div class="card">
          <h3>Cloud Solutions</h3>
          <p>Scalable cloud infrastructure and deployment</p>
        </div>
        <div class="card">
          <h3>Data Analytics</h3>
          <p>Turn data into actionable insights</p>
        </div>
        <div class="card">
          <h3>AI & Machine Learning</h3>
          <p>Intelligent solutions for complex problems</p>
        </div>
      </div>
      <p style="text-align: center; color: #666;">
        Uses: :hover, :active, :nth-child() for varied border colors
      </p>
    </div>
    
    <!-- Button Group -->
    <div class="form-container">
      <h2>🔘 Button States & Interactions</h2>
      <div class="button-group">
        <button class="btn btn-primary">Primary Action</button>
        <button class="btn btn-secondary">Secondary Action</button>
        <button class="btn btn-primary" disabled>Disabled Button</button>
        <button class="btn btn-secondary">Another Button</button>
      </div>
      <p style="color: #666;">
        Uses: :hover, :active, :focus, :disabled for button states
      </p>
    </div>
    
    <!-- Form Validation -->
    <div class="form-container">
      <h2>📝 Smart Form Validation</h2>
      <form>
        <div class="form-group">
          <label>Email Address *</label>
          <input type="email" required placeholder="Enter valid email">
        </div>
        <div class="form-group">
          <label>Password *</label>
          <input type="password" required minlength="6" placeholder="Minimum 6 characters">
        </div>
        <div class="form-group">
          <label>Phone Number (Optional)</label>
          <input type="tel" placeholder="Optional field">
        </div>
        <button class="btn btn-primary" type="submit">Create Account</button>
      </form>
      <p style="color: #666; margin-top: 1rem;">
        Uses: :required, :optional, :valid, :invalid, :focus for form validation
      </p>
    </div>
    
    <!-- Progress Steps -->
    <div class="progress-steps">
      <div class="step active">Sign Up</div>
      <div class="step active">Profile</div>
      <div class="step">Preferences</div>
      <div class="step">Confirmation</div>
    </div>
    <p style="text-align: center; color: #666;">
      Uses: :not(), :before, counters for progress indicators
    </p>
  </div>
</body>
</html>

Best Practices & Common Patterns

✅ Do This

Use :focus for accessibility
Combine pseudo-classes like :hover:focus
Use :nth-child for complex patterns
Test with keyboard navigation
Use :not() for exclusion patterns
Provide fallbacks for older browsers

❌ Avoid This

Overusing complex :nth-child formulas
Forgetting to style :focus states
Using :hover on non-interactive elements
Ignoring touch device limitations
Creating inaccessible color contrasts
Overcomplicating with too many states

🎯 Pseudo-Class Specificity

Order Matters:

:link → :visited
:hover → :active
:focus should be considered

Specificity Weight:

Pseudo-classes: 0,1,0
Same as class selectors
Less than ID selectors

Browser Support & Compatibility

Modern Pseudo-Class Support

:hover

99.9%

:focus

99.9%

:nth-child

99%

:valid/:invalid

98%

:focus-within

96%

:where()

92%

:is()

92%

:has()

88%

Ready to Master Pseudo-Classes? 🎯

Experiment with our interactive examples and discover the power of CSS pseudo-classes. Create dynamic, accessible, and engaging user interfaces with pure CSS!

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