body{background:linear-gradient(135deg,#667eea,#764ba2);font-family:Arial,sans-serif;margin:0 auto;max-width:800px;min-height:100vh;
  padding:20px}.container{background:#fff;border-radius:15px;box-shadow:0 10px 30px rgba(0,0,0,.2);
  padding:30px}h1{color:#333;margin-bottom:30px;text-align:center}.feature-box{background:#f8f9fa;border:2px solid #e9ecef;border-radius:10px;
  margin:15px 0;padding:20px;transition:all .3s ease}.feature-box:hover{background:#e3f2fd;border-color:#2196f3;transform:translateY(-2px)}
  button{background:linear-gradient(45deg,#2196f3,#21cbf3);border:none;
  border-radius:25px;color:#fff;cursor:pointer;font-size:16px;margin:5px;padding:12px 25px;transition:all .3s ease}
  button:hover{box-shadow:0 5px 15px rgba(33,150,243,.4);transform:scale(1.05)}
  .result{background:#e8f5e8;border:2px solid #4caf50;border-radius:10px;display:none;margin:15px 0;padding:15px}
  .counter{color:#2196f3;font-size:24px;font-weight:700;margin:20px 0;text-align:center}
  input[type=text]{border:2px solid #ddd;border-radius:8px;font-size:16px;margin:10px 0;padding:
  12px;width:100%}.color-demo{background:#ff6b6b;border-radius:50%;height:100px;margin:20px auto;transition:all .5s ease;width:100px
}