* {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }

    body {
      font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
      line-height: 1.6;
      color: #302f2f;
      background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
      min-height: 100vh;
      padding: 20px;  
    }

    .container {
      max-width: 900px;
      margin: 0 auto;
      background: rgba(255, 255, 255, 0.95);
      border-radius: 20px;
      box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
      backdrop-filter: blur(10px);
      overflow: hidden;
      padding: 20px;
    }
     
    .back-button {
      background: linear-gradient(45deg, #3498db, #2980b9);
      color:white; padding:12px 25px; border-radius:25px;
      text-decoration:none; margin-bottom:30px; display:inline-block;
    }

    .header {
      text-align: center;
      color: rgb(67, 64, 64);
    }

    .header h1 {
      font-size: 3em;
      margin-bottom: 10px;
      text-shadow: 2px 2px 4px rgba(29, 16, 44, 0.3);
    }

    .header p {
      font-size: 1.2em;
      opacity: 0.9;
    }

    .content {
      padding: 40px;
    }

    .section {
      margin-bottom: 40px;
      padding: 30px;
      background: rgba(251, 251, 251, 0.972);
      border-radius: 15px;
      border-left: 5px solid #2980b9;
      transition: transform 0.3s ease;
    }

    .section:hover {
      transform: translateY(-5px);
      box-shadow: 0 10px 20px rgba(0, 0, 0, 0.1);
    }

    .section h2 {
      color: #2c3e50;
      margin-bottom: 20px;
      font-size: 2em;
      display: flex;
      align-items: center;
      gap: 10px;
    }

    .icon {
      font-size: 1.2em;
    }

    .examples-grid {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
      gap: 20px;
      margin: 20px 0;
    }

    .example-card {
      background: linear-gradient(135deg, #f6f6f6 0%, #ffffff 100%);
      padding: 20px;
      border-radius: 10px;
      box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
    }

    .example-card h4 {
      color: #2c3e50;
      margin-bottom: 10px;
    }

    .example-card p {
      margin: 5px 0;
      font-size: 1.1em;
    }

    .key-points {
      background: linear-gradient(135deg, #ffecd2 0%, #fcb69f 100%);
      padding: 30px;
      border-radius: 15px;
      margin: 20px 0;
    }

    .key-points li {
      margin: 10px 0;
      padding: 10px;
      background: rgba(255, 255, 255, 0.7);
      border-radius: 8px;
      border-left: 4px solid #ff6b6b;
      font-weight: 500;
    }

    .activity {
      background: linear-gradient(135deg, #d299c2 0%, #fef9d7 100%);
      padding: 30px;
      border-radius: 15px;
      margin: 20px 0;
    }

    .question {
      background: rgba(255, 255, 255, 0.7);
      padding: 15px;
      margin: 15px 0;
      border-radius: 8px;
      border-left: 4px solid #9b59b6;
    }

    .input-field {
      width: 100%;
      padding: 10px;
      margin: 10px 0;
      border: 2px solid #ddd;
      border-radius: 5px;
      font-size: 1em;
    }

    .check-btn {
      background: linear-gradient(135deg, #36d1dc 0%, #5b86e5 100%);
      color: white;
      border: none;
      padding: 12px 25px;
      border-radius: 25px;
      cursor: pointer;
      font-size: 1em;
      transition: transform 0.2s ease;
    }

    .check-btn:hover {
      transform: scale(1.05);
    }

    .result {
      margin: 10px 0;
      padding: 10px;
      border-radius: 5px;
      font-weight: bold;
    }

    .correct {
      background: #d4edda;
      color: #155724;
      border: 1px solid #c3e6cb;
    }

    .incorrect {
      background: #f8d7da;
      color: #721c24;
      border: 1px solid #f5c6cb;
    }