/* General Styles */
body {
    margin: 0;
    font-family: 'Poppins', sans-serif;
    height: 100vh;
    overflow: hidden;
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column; /* Added to stack the heading and calculator vertically */
    background: linear-gradient(45deg, #0f2027, #2c5364, #203a43);
    background-size: 300% 300%;
    animation: gradientFlow 8s infinite;
    color: #ffffff;
  }
  
  /* Background Animation */
  @keyframes gradientFlow {
    0% {
      background-position: 0% 50%;
    }
    50% {
      background-position: 100% 50%;
    }
    100% {
      background-position: 0% 50%;
    }
  }
  
  /* Heading Styles */
  .heading {
    text-align: center;
    font-size: 2.5rem;
    color: #ffffff;
    margin-bottom: 20px;
    text-shadow: 2px 2px 10px rgba(0, 0, 0, 0.5);
    font-weight: bold;
  }
  
  /* Calculator Container */
  .calculator {
    z-index: 1;
    width: 360px;
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    border-radius: 20px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5);
    overflow: hidden;
    transition: transform 0.4s ease-in-out;
  }
  
  .calculator:hover {
    transform: translateY(-10px) scale(1.05);
  }
  
  /* Display Styles */
  .display {
    background: rgba(255, 255, 255, 0.15);
    padding: 25px;
    font-size: 2rem;
    color: #f8f8f8;
    text-align: right;
    border-bottom: 2px solid rgba(255, 255, 255, 0.3);
    font-weight: bold;
    letter-spacing: 1px;
  }
  
  /* Button Grid */
  .buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
    padding: 20px;
  }
  
  /* Buttons */
  .btn {
    background: rgba(255, 255, 255, 0.2);
    color: #ffffff;
    font-size: 1.5rem;
    border: none;
    border-radius: 12px;
    padding: 15px;
    cursor: pointer;
    transition: transform 0.3s ease, background-color 0.3s ease;
    box-shadow: 0 5px 10px rgba(0, 0, 0, 0.3);
  }
  
  .btn:hover {
    transform: scale(1.1);
    background: rgba(255, 255, 255, 0.4);
    color: #000000;
  }
  
  /* Operator Buttons */
  .operator {
    background: rgba(255, 69, 58, 0.8);
    color: #ffffff;
  }
  
  .operator:hover {
    background: rgba(255, 69, 58, 1);
    color: #ffffff;
  }
  
  /* Equals Button */
  .equals {
    grid-column: span 2;
    background: rgba(10, 132, 255, 0.9);
    color: #ffffff;
    font-weight: bold;
  }
  
  .equals:hover {
    background: rgba(10, 132, 255, 1);
    transform: scale(1.15);
  }
  
  /* Subtle Floating Animation for Calculator */
  @keyframes float {
    0%, 100% {
      transform: translateY(0);
    }
    50% {
      transform: translateY(-15px);
    }
  }
  
  .calculator {
    animation: float 6s ease-in-out infinite;
  }
  