Critical CSS ⚡

Load above-the-fold content instantly while deferring non-critical styles for maximum performance.

What is Critical CSS?

Critical CSS is the practice of extracting and inlining the CSS needed to render the visible portion of a webpage (above the fold), while deferring non-critical styles. This eliminates render-blocking resources and creates the perception of instant loading.

🚀 Instant Rendering

Above-the-fold content loads immediately

📈 Better UX

Users see content faster

🏆 Higher Conversions

Improved engagement and sales

🛒 E-commerce Flash Sale

Critical Elements:

Product image & price - Immediate purchase decision
Countdown timer - Creates urgency
Buy button - Primary conversion element
Hero section styling - Visual appeal

Flash Sale Implementation

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>🚀 Flash Sale - Critical CSS in Action</title>
  <style>
    /* === CRITICAL CSS - Above the Fold === */
    .flash-sale-hero {
      background: linear-gradient(135deg, #ff6b6b 0%, #ee5a24 100%);
      color: white;
      padding: 4rem 2rem;
      text-align: center;
      animation: slideIn 0.8s ease-out;
    }
    
    .countdown-timer {
      font-size: 3rem;
      font-weight: bold;
      margin: 2rem 0;
      text-shadow: 2px 2px 4px rgba(0,0,0,0.3);
    }
    
    .timer-unit {
      display: inline-block;
      margin: 0 1rem;
      padding: 1rem;
      background: rgba(255,255,255,0.2);
      border-radius: 10px;
      min-width: 80px;
    }
    
    .buy-now-btn {
      background: #ffdd59;
      color: #2d3436;
      padding: 1.5rem 3rem;
      font-size: 1.5rem;
      font-weight: bold;
      border: none;
      border-radius: 50px;
      cursor: pointer;
      transition: all 0.3s ease;
      box-shadow: 0 4px 15px rgba(0,0,0,0.2);
    }
    
    .buy-now-btn:hover {
      transform: translateY(-3px);
      box-shadow: 0 6px 20px rgba(0,0,0,0.3);
      background: #ffd32a;
    }
    
    .product-image {
      width: 300px;
      height: 300px;
      object-fit: cover;
      border-radius: 20px;
      box-shadow: 0 8px 25px rgba(0,0,0,0.3);
      margin: 2rem auto;
      display: block;
    }
    
    @keyframes slideIn {
      from {
        opacity: 0;
        transform: translateY(50px);
      }
      to {
        opacity: 1;
        transform: translateY(0);
      }
    }
    
    /* === NON-CRITICAL CSS - Below the Fold === */
    .customer-reviews {
      opacity: 0;
      animation: fadeIn 1s ease 1s forwards;
    }
    
    .related-products {
      opacity: 0;
      animation: fadeIn 1s ease 2s forwards;
    }
    
    .footer {
      opacity: 0;
      animation: fadeIn 1s ease 3s forwards;
    }
    
    @keyframes fadeIn {
      to { opacity: 1; }
    }
  </style>
</head>
<body>
  <!-- 🚀 CRITICAL CONTENT - Above the Fold -->
  <section class="flash-sale-hero">
    <h1>🔥 LIMITED TIME OFFER!</h1>
    <p>Next-Gen Smart Watch Pro - 60% OFF</p>
    
    <div class="countdown-timer">
      <span class="timer-unit">
        <div id="hours">24</div>
        <small>HOURS</small>
      </span>
      <span class="timer-unit">
        <div id="minutes">00</div>
        <small>MINUTES</small>
      </span>
      <span class="timer-unit">
        <div id="seconds">00</div>
        <small>SECONDS</small>
      </span>
    </div>
    
    <img src="data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='300' height='300' viewBox='0 0 300 300'%3E%3Crect width='300' height='300' fill='%233498db' rx='20'/%3E%3Ccircle cx='150' cy='120' r='40' fill='%23fff'/%3E%3Crect x='110' y='180' width='80' height='60' fill='%23fff' rx='10'/%3E%3C/svg%3E" 
         alt="Smart Watch Pro" class="product-image">
    
    <button class="buy-now-btn" onclick="alert('🚀 Purchase initiated!')">
      🛒 BUY NOW - $99
    </button>
  </section>

  <!-- 📝 NON-CRITICAL CONTENT - Below the Fold -->
  <section class="customer-reviews">
    <h2>⭐ Customer Reviews</h2>
    <p>"This watch changed my life! Battery lasts for days!" - Sarah M.</p>
  </section>

  <section class="related-products">
    <h2>🛍️ You Might Also Like</h2>
    <p>Smart Watch Accessories</p>
  </section>

  <footer class="footer">
    <p>© 2024 TechGadgets Inc.</p>
  </footer>

  <script>
    // Countdown timer for urgency
    function updateCountdown() {
      const hours = document.getElementById('hours');
      const minutes = document.getElementById('minutes');
      const seconds = document.getElementById('seconds');
      
      let timeLeft = 24 * 60 * 60; // 24 hours in seconds
      
      setInterval(() => {
        if (timeLeft > 0) {
          timeLeft--;
          const hrs = Math.floor(timeLeft / 3600);
          const mins = Math.floor((timeLeft % 3600) / 60);
          const secs = timeLeft % 60;
          
          hours.textContent = hrs.toString().padStart(2, '0');
          minutes.textContent = mins.toString().padStart(2, '0');
          seconds.textContent = secs.toString().padStart(2, '0');
        }
      }, 1000);
    }
    
    updateCountdown();
  </script>
</body>
</html>

📰 Breaking News Article

Critical Content

Elements that readers need immediately:

🚨 Breaking news banner

📖 Article headline

✍️ Lead paragraph

🖼️ Featured image

Deferred Content

Can load after initial render:

💬 Comments section

📚 Related articles

📊 Social sharing

🔍 Search functionality

News Article Implementation

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>📰 Breaking News - Critical CSS Optimization</title>
  <style>
    /* === CRITICAL CSS - Immediate Reading Experience === */
    .breaking-news-banner {
      background: linear-gradient(45deg, #e74c3c, #c0392b);
      color: white;
      padding: 1rem;
      text-align: center;
      font-weight: bold;
      font-size: 1.2rem;
      position: sticky;
      top: 0;
      z-index: 1000;
      animation: pulse 2s infinite;
    }
    
    .article-header {
      padding: 2rem;
      max-width: 800px;
      margin: 0 auto;
      font-family: 'Georgia', serif;
    }
    
    .article-title {
      font-size: 3rem;
      line-height: 1.2;
      margin-bottom: 1rem;
      color: #2c3e50;
      text-shadow: 1px 1px 2px rgba(0,0,0,0.1);
    }
    
    .article-meta {
      color: #7f8c8d;
      font-size: 0.9rem;
      margin-bottom: 2rem;
      border-bottom: 2px solid #ecf0f1;
      padding-bottom: 1rem;
    }
    
    .article-lead {
      font-size: 1.4rem;
      line-height: 1.6;
      color: #34495e;
      font-weight: 500;
      margin-bottom: 2rem;
      background: #f8f9fa;
      padding: 1.5rem;
      border-left: 4px solid #3498db;
      border-radius: 0 8px 8px 0;
    }
    
    .article-content {
      line-height: 1.8;
      font-size: 1.1rem;
      opacity: 0;
      animation: typeIn 2s ease 0.5s forwards;
    }
    
    .featured-image {
      width: 100%;
      max-width: 600px;
      height: 400px;
      object-fit: cover;
      border-radius: 12px;
      margin: 2rem auto;
      display: block;
      box-shadow: 0 8px 25px rgba(0,0,0,0.15);
      opacity: 0;
      animation: zoomIn 1s ease 1s forwards;
    }
    
    @keyframes pulse {
      0%, 100% { opacity: 1; }
      50% { opacity: 0.8; }
    }
    
    @keyframes typeIn {
      from {
        opacity: 0;
        transform: translateY(20px);
      }
      to {
        opacity: 1;
        transform: translateY(0);
      }
    }
    
    @keyframes zoomIn {
      from {
        opacity: 0;
        transform: scale(0.9);
      }
      to {
        opacity: 1;
        transform: scale(1);
      }
    }
    
    /* === NON-CRITICAL CSS - Secondary Content === */
    .related-articles {
      opacity: 0;
      animation: fadeInUp 1s ease 2s forwards;
    }
    
    .comments-section {
      opacity: 0;
      animation: fadeInUp 1s ease 3s forwards;
    }
    
    @keyframes fadeInUp {
      to {
        opacity: 1;
        transform: translateY(0);
      }
      from {
        opacity: 0;
        transform: translateY(20px);
      }
    }
  </style>
</head>
<body>
  <!-- 🚨 CRITICAL - Breaking News Banner -->
  <div class="breaking-news-banner">
    🚨 BREAKING: Major Scientific Discovery Announced
  </div>

  <!-- 📖 CRITICAL - Article Content -->
  <article class="article-header">
    <h1 class="article-title">
      Scientists Discover New Energy Source That Could Power Cities for Centuries
    </h1>
    
    <div class="article-meta">
      <strong>By Dr. Sarah Chen</strong> | 
      <span>Physics Today</span> | 
      <time datetime="2024-01-15">January 15, 2024</time> |
      <span>🕒 5 min read</span>
    </div>
    
    <div class="article-lead">
      Groundbreaking research reveals a revolutionary energy technology that harnesses quantum fluctuations 
      to generate clean, limitless power. Early tests show potential to replace fossil fuels entirely.
    </div>
    
    <img src="data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='600' height='400' viewBox='0 0 600 400'%3E%3Crect width='600' height='400' fill='%232c3e50'/%3E%3Ccircle cx='300' cy='200' r='80' fill='%233498db'/%3E%3Cpath d='M300,120 L320,180 L380,180 L330,220 L350,280 L300,240 L250,280 L270,220 L220,180 L280,180 Z' fill='%23f1c40f'/%3E%3C/svg%3E" 
         alt="Quantum Energy Reactor" class="featured-image">
    
    <div class="article-content">
      <p>In a stunning development that could reshape global energy markets, an international team of researchers 
      has successfully demonstrated a new form of energy generation that taps into the fundamental fabric of spacetime.</p>
      
      <p>The technology, dubbed "Quantum Vacuum Energy Extraction," utilizes advanced nanomaterials to capture 
      and convert zero-point energy into usable electricity. Early prototype reactors have shown remarkable 
      stability and output levels that exceed current nuclear fusion predictions.</p>
      
      <p>"This isn't just incremental progress—it's a complete paradigm shift," said lead researcher Dr. Chen. 
      "We're looking at energy densities orders of magnitude beyond anything previously imagined."</p>
    </div>
  </article>

  <!-- 📰 NON-CRITICAL - Related Content -->
  <section class="related-articles">
    <h3>📚 Related Articles</h3>
    <p>Quantum Computing Breakthrough | Renewable Energy Trends 2024</p>
  </section>

  <section class="comments-section">
    <h3>💬 Join the Discussion</h3>
    <p>What do you think about this discovery?</p>
  </section>

  <script>
    // Simulate progressive content loading
    setTimeout(() => {
      document.querySelector('.article-content').innerHTML += `
        <p><strong>Commercial Applications:</strong> The first commercial reactors are expected to be deployed 
        within 5 years, with initial installations planned for major metropolitan areas. Early cost projections 
        suggest energy prices could drop by over 80% compared to current rates.</p>
        
        <p><strong>Environmental Impact:</strong> Unlike fossil fuels or conventional nuclear power, the quantum 
        energy process produces zero emissions and generates minimal waste. The reactors are also remarkably 
        compact, with a unit capable of powering a small city fitting in a standard shipping container.</p>
      `;
    }, 3000);
  </script>
</body>
</html>

💼 Creative Portfolio

First Impression Matters

For portfolios, the hero section is everything. Critical CSS ensures potential clients see your best work immediately while the rest loads seamlessly in the background.

// Critical: Hero, Name, CTA buttons

// Deferred: Project grid, Contact form

Portfolio Implementation

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>💼 Creative Portfolio - Critical CSS Magic</title>
  <style>
    /* === CRITICAL CSS - First Impression === */
    .hero-section {
      background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
      color: white;
      min-height: 100vh;
      display: flex;
      align-items: center;
      justify-content: center;
      text-align: center;
      position: relative;
      overflow: hidden;
    }
    
    .hero-content {
      z-index: 2;
      animation: heroEntrance 1.5s ease-out;
    }
    
    .profile-avatar {
      width: 150px;
      height: 150px;
      border-radius: 50%;
      border: 4px solid rgba(255,255,255,0.3);
      margin: 0 auto 2rem;
      background: linear-gradient(45deg, #fd746c, #ff9068);
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 3rem;
      animation: float 3s ease-in-out infinite;
    }
    
    .hero-title {
      font-size: 4rem;
      font-weight: 700;
      margin-bottom: 1rem;
      text-shadow: 2px 2px 4px rgba(0,0,0,0.3);
    }
    
    .hero-subtitle {
      font-size: 1.5rem;
      margin-bottom: 2rem;
      opacity: 0.9;
    }
    
    .cta-buttons {
      display: flex;
      gap: 1rem;
      justify-content: center;
      flex-wrap: wrap;
    }
    
    .cta-primary, .cta-secondary {
      padding: 1rem 2rem;
      border: none;
      border-radius: 50px;
      font-size: 1.1rem;
      font-weight: 600;
      cursor: pointer;
      transition: all 0.3s ease;
      text-decoration: none;
      display: inline-block;
    }
    
    .cta-primary {
      background: #ffdd59;
      color: #2d3436;
      box-shadow: 0 4px 15px rgba(255,221,89,0.3);
    }
    
    .cta-primary:hover {
      transform: translateY(-2px);
      box-shadow: 0 6px 20px rgba(255,221,89,0.4);
    }
    
    .cta-secondary {
      background: transparent;
      color: white;
      border: 2px solid rgba(255,255,255,0.3);
    }
    
    .cta-secondary:hover {
      background: rgba(255,255,255,0.1);
      border-color: rgba(255,255,255,0.5);
    }
    
    .floating-shapes {
      position: absolute;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      pointer-events: none;
    }
    
    .shape {
      position: absolute;
      opacity: 0.1;
      animation: float 6s ease-in-out infinite;
    }
    
    .shape:nth-child(1) {
      top: 20%;
      left: 10%;
      animation-delay: 0s;
    }
    
    .shape:nth-child(2) {
      top: 60%;
      right: 10%;
      animation-delay: 2s;
    }
    
    .shape:nth-child(3) {
      bottom: 20%;
      left: 20%;
      animation-delay: 4s;
    }
    
    @keyframes heroEntrance {
      from {
        opacity: 0;
        transform: translateY(50px) scale(0.9);
      }
      to {
        opacity: 1;
        transform: translateY(0) scale(1);
      }
    }
    
    @keyframes float {
      0%, 100% {
        transform: translateY(0) rotate(0deg);
      }
      50% {
        transform: translateY(-20px) rotate(180deg);
      }
    }
    
    /* === NON-CRITICAL CSS - Portfolio Content === */
    .portfolio-grid {
      opacity: 0;
      animation: fadeInUp 1s ease 1s forwards;
    }
    
    .skills-section {
      opacity: 0;
      animation: fadeInUp 1s ease 2s forwards;
    }
    
    .contact-section {
      opacity: 0;
      animation: fadeInUp 1s ease 3s forwards;
    }
    
    @keyframes fadeInUp {
      to {
        opacity: 1;
        transform: translateY(0);
      }
      from {
        opacity: 0;
        transform: translateY(30px);
      }
    }
  </style>
</head>
<body>
  <!-- 🌟 CRITICAL - Hero Section -->
  <section class="hero-section">
    <div class="floating-shapes">
      <div class="shape">🔮</div>
      <div class="shape">🎨</div>
      <div class="shape">⚡</div>
    </div>
    
    <div class="hero-content">
      <div class="profile-avatar">
        👨‍💻
      </div>
      
      <h1 class="hero-title">
        Alex Creative
      </h1>
      
      <p class="hero-subtitle">
        Digital Alchemist • UI/UX Wizard • Code Poet
      </p>
      
      <p style="margin-bottom: 2rem; max-width: 500px; line-height: 1.6;">
        I transform complex ideas into elegant digital experiences. 
        Specializing in reactive design, performance optimization, and creating 
        interfaces that feel like magic.
      </p>
      
      <div class="cta-buttons">
        <button class="cta-primary" onclick="showMagic()">
          🎩 See Magic
        </button>
        <a href="#projects" class="cta-secondary">
          📁 View Work
        </a>
      </div>
    </div>
  </section>

  <!-- 📂 NON-CRITICAL - Portfolio Content -->
  <section class="portfolio-grid" id="projects">
    <h2>Featured Projects</h2>
    <p>Coming soon... (Loading additional content)</p>
  </section>

  <section class="skills-section">
    <h2>Skills & Expertise</h2>
    <p>Loading skills...</p>
  </section>

  <section class="contact-section">
    <h2>Let's Create Magic Together</h2>
    <p>Contact form loading...</p>
  </section>

  <script>
    function showMagic() {
      const hero = document.querySelector('.hero-section');
      hero.style.background = 'linear-gradient(135deg, #ff6b6b 0%, #feca57 100%)';
      
      const avatar = document.querySelector('.profile-avatar');
      avatar.innerHTML = '✨';
      avatar.style.background = 'linear-gradient(45deg, #ff9a9e, #fad0c4)';
      avatar.style.transform = 'scale(1.2)';
      
      setTimeout(() => {
        avatar.innerHTML = '👨‍💻';
        avatar.style.transform = 'scale(1)';
        hero.style.background = 'linear-gradient(135deg, #667eea 0%, #764ba2 100%)';
      }, 2000);
    }
    
    // Simulate loading portfolio content
    setTimeout(() => {
      document.querySelector('.portfolio-grid').innerHTML = `
        <h2>🚀 Featured Projects</h2>
        <div style="display: grid; grid-template-columns: repeat(auto-fit, minmax(250px, 1fr)); gap: 2rem; margin-top: 2rem;">
          <div style="background: #f8f9fa; padding: 2rem; border-radius: 12px; text-align: center;">
            <h3>Neural Network Visualizer</h3>
            <p>Interactive AI visualization tool</p>
          </div>
          <div style="background: #f8f9fa; padding: 2rem; border-radius: 12px; text-align: center;">
            <h3>Quantum UI Framework</h3>
            <p>Next-gen reactive components</p>
          </div>
        </div>
      `;
    }, 2000);
  </script>
</body>
</html>

🎮 Game Launch Page

🚀 Game Title

Immediate brand recognition

🎯 Play Button

Primary conversion action

🦾 Character Preview

Visual engagement

Gaming Implementation

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>🎮 Game Launch - Critical CSS for Gamers</title>
  <style>
    /* === CRITICAL CSS - Game Experience === */
    .game-launch-hero {
      background: linear-gradient(135deg, #0c2461 0%, #1e3799 50%, #4a69bd 100%);
      color: white;
      min-height: 100vh;
      display: flex;
      align-items: center;
      justify-content: center;
      text-align: center;
      position: relative;
      overflow: hidden;
    }
    
    .game-title {
      font-size: 5rem;
      font-weight: 900;
      margin-bottom: 1rem;
      text-shadow: 3px 3px 0 #000, 6px 6px 0 rgba(0,0,0,0.2);
      background: linear-gradient(45deg, #f6d365 0%, #fda085 100%);
      -webkit-background-clip: text;
      -webkit-text-fill-color: transparent;
      animation: titleGlow 2s ease-in-out infinite alternate;
    }
    
    .game-subtitle {
      font-size: 1.5rem;
      margin-bottom: 3rem;
      opacity: 0.9;
      text-shadow: 1px 1px 2px rgba(0,0,0,0.5);
    }
    
    .play-now-btn {
      background: linear-gradient(45deg, #e74c3c, #c0392b);
      color: white;
      padding: 1.5rem 4rem;
      font-size: 1.5rem;
      font-weight: bold;
      border: none;
      border-radius: 10px;
      cursor: pointer;
      transition: all 0.3s ease;
      box-shadow: 0 8px 25px rgba(231, 76, 60, 0.3);
      text-transform: uppercase;
      letter-spacing: 2px;
      position: relative;
      overflow: hidden;
    }
    
    .play-now-btn:hover {
      transform: translateY(-3px) scale(1.05);
      box-shadow: 0 12px 35px rgba(231, 76, 60, 0.4);
    }
    
    .play-now-btn:active {
      transform: translateY(-1px) scale(1.02);
    }
    
    .game-stats {
      display: flex;
      gap: 3rem;
      margin: 3rem 0;
      justify-content: center;
      flex-wrap: wrap;
    }
    
    .stat-item {
      text-align: center;
    }
    
    .stat-number {
      font-size: 2.5rem;
      font-weight: bold;
      color: #f1c40f;
      text-shadow: 2px 2px 0 rgba(0,0,0,0.3);
    }
    
    .stat-label {
      font-size: 0.9rem;
      opacity: 0.8;
      text-transform: uppercase;
      letter-spacing: 1px;
    }
    
    .character-preview {
      width: 200px;
      height: 200px;
      margin: 2rem auto;
      background: linear-gradient(45deg, #fd746c, #ff9068);
      border-radius: 20px;
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 4rem;
      box-shadow: 0 10px 30px rgba(0,0,0,0.3);
      animation: characterFloat 4s ease-in-out infinite;
    }
    
    @keyframes titleGlow {
      from {
        filter: drop-shadow(0 0 10px rgba(246, 211, 101, 0.5));
      }
      to {
        filter: drop-shadow(0 0 20px rgba(246, 211, 101, 0.8));
      }
    }
    
    @keyframes characterFloat {
      0%, 100% {
        transform: translateY(0) rotate(0deg);
      }
      33% {
        transform: translateY(-10px) rotate(5deg);
      }
      66% {
        transform: translateY(-5px) rotate(-5deg);
      }
    }
    
    .particles {
      position: absolute;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      pointer-events: none;
    }
    
    .particle {
      position: absolute;
      background: rgba(255,255,255,0.5);
      border-radius: 50%;
      animation: particleFloat linear infinite;
    }
    
    @keyframes particleFloat {
      to {
        transform: translateY(-100vh) rotate(360deg);
      }
    }
    
    /* === NON-CRITICAL CSS - Game Details === */
    .game-features {
      opacity: 0;
      animation: slideInFromBottom 1s ease 1s forwards;
    }
    
    .system-requirements {
      opacity: 0;
      animation: slideInFromBottom 1s ease 2s forwards;
    }
    
    @keyframes slideInFromBottom {
      to {
        opacity: 1;
        transform: translateY(0);
      }
      from {
        opacity: 0;
        transform: translateY(50px);
      }
    }
  </style>
</head>
<body>
  <!-- 🎮 CRITICAL - Game Launch Experience -->
  <section class="game-launch-hero">
    <div class="particles" id="particles"></div>
    
    <div class="hero-content">
      <h1 class="game-title">
        CYBER LEGENDS
      </h1>
      
      <p class="game-subtitle">
        Enter the neon-drenched world of 2084. Fight for survival in a dystopian metropolis.
      </p>
      
      <div class="character-preview">
        🦾
      </div>
      
      <div class="game-stats">
        <div class="stat-item">
          <div class="stat-number">4.9/5</div>
          <div class="stat-label">Player Rating</div>
        </div>
        <div class="stat-item">
          <div class="stat-number">50K+</div>
          <div class="stat-label">Active Players</div>
        </div>
        <div class="stat-item">
          <div class="stat-number">120</div>
          <div class="stat-label">Weapons</div>
        </div>
      </div>
      
      <button class="play-now-btn" onclick="startGame()">
        🎯 PLAY NOW - FREE
      </button>
    </div>
  </section>

  <!-- 🎪 NON-CRITICAL - Additional Content -->
  <section class="game-features">
    <h2>⚡ Game Features</h2>
    <p>Open world • Customizable cyberware • Multiplayer battles • Daily events</p>
  </section>

  <section class="system-requirements">
    <h2>💻 System Requirements</h2>
    <p>Loading specifications...</p>
  </section>

  <script>
    function startGame() {
      const btn = document.querySelector('.play-now-btn');
      const originalText = btn.innerHTML;
      
      btn.innerHTML = '🚀 LAUNCHING...';
      btn.style.background = 'linear-gradient(45deg, #2ecc71, #27ae60)';
      
      setTimeout(() => {
        btn.innerHTML = '🎮 GAME STARTED!';
        btn.style.background = 'linear-gradient(45deg, #9b59b6, #8e44ad)';
        
        // Add explosion effect
        for(let i = 0; i < 50; i++) {
          createParticle();
        }
      }, 1500);
    }
    
    function createParticle() {
      const particle = document.createElement('div');
      particle.className = 'particle';
      particle.style.left = Math.random() * 100 + 'vw';
      particle.style.width = Math.random() * 10 + 5 + 'px';
      particle.style.height = particle.style.width;
      particle.style.animationDuration = Math.random() * 3 + 2 + 's';
      particle.style.background = `hsl(${Math.random() * 360}, 100%, 50%)`;
      
      document.getElementById('particles').appendChild(particle);
      
      setTimeout(() => particle.remove(), 5000);
    }
    
    // Create background particles
    for(let i = 0; i < 30; i++) {
      createParticle();
    }
    
    // Load additional content
    setTimeout(() => {
      document.querySelector('.system-requirements').innerHTML = `
        <h2>💻 System Requirements</h2>
        <div style="display: grid; grid-template-columns: 1fr 1fr; gap: 2rem; margin-top: 1rem;">
          <div>
            <h3>Minimum</h3>
            <p>GPU: RTX 2060<br>RAM: 8GB<br>Storage: 50GB</p>
          </div>
          <div>
            <h3>Recommended</h3>
            <p>GPU: RTX 4070<br>RAM: 16GB<br>Storage: 100GB SSD</p>
          </div>
        </div>
      `;
    }, 3000);
  </script>
</body>
</html>

Real-World Impact

📈 Performance Benefits

50-80% faster FCP (First Contentful Paint)
2-3x improvement in perceived performance
15-30% higher conversion rates
Better SEO rankings from Core Web Vitals
Improved user engagement and retention

🎯 Implementation Strategy

Identify above-the-fold content
Extract critical CSS rules
Inline critical CSS in <head>
Defer non-critical styles
Test across devices and viewports

💡 Pro Tips for Critical CSS

Tools & Automation:

Use Critical CSS extraction tools
Integrate with build processes
Automate for different viewports
Monitor performance regularly

Best Practices:

Keep critical CSS under 14KB
Test on real devices
Consider mobile-first approach
Update with design changes

Ready to Speed Up Your Website? ⚡

Implement Critical CSS to create lightning-fast loading experiences that keep users engaged and improve your conversion rates. See the dramatic difference it makes in real-world scenarios.

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