/* General Styles */
body {
    font-family: 'Poppins', sans-serif;
    background: linear-gradient(135deg, #1c1c1c, #444); /* Elegant dark gradient */
    color: white;
    margin: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
  }
  
  .calculator {
    width: 350px;
    background: #222; /* Dark calculator background */
    border-radius: 15px;
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.6); /* Enhanced shadow */
    overflow: hidden;
    padding: 20px;
  }
  
  /* Screen */
  .screen {
    background: #000; /* Darker screen background */
    border: 1px solid #555; /* Subtle border */
    padding: 10px;
    border-radius: 10px;
    margin-bottom: 20px;
  }
  
  .screen input {
    width: 100%;
    font-size: 2.2rem;
    font-weight: bold;
    color: #00ff99; /* Bright green font */
    background: none;
    border: none;
    text-align: right;
    outline: none;
  }
  
  /* Buttons */
  .buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr); /* 4 buttons per row */
    gap: 10px;
  }
  
  .btn {
    background: #444; /* Neutral dark background */
    border: none;
    padding: 15px;
    font-size: 1.4rem;
    color: white;
    border-radius: 8px;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.4); /* Button shadow */
    cursor: pointer;
    transition: all 0.3s ease;
  }
  
  .btn:hover {
    background: #555; /* Lighter on hover */
    transform: translateY(-2px);
    box-shadow: 0 6px 12px rgba(0, 0, 0, 0.5);
  }
  
  .operator {
    background: linear-gradient(to right, #ff7e5f, #feb47b); /* Gradient for operators */
  }
  
  .operator:hover {
    background: linear-gradient(to right, #feb47b, #ff7e5f);
  }
  
  .equal {
    grid-column: span 2; /* Spanning full width */
    background: linear-gradient(to right, #36d1dc, #5b86e5);
    color: white;
  }
  
  .equal:hover {
    background: linear-gradient(to right, #5b86e5, #36d1dc);
  }
  
  .clear {
    background: linear-gradient(to right, #ff416c, #ff4b2b); /* Clear button gradient */
  }
  
  .clear:hover {
    background: linear-gradient(to right, #ff4b2b, #ff416c);
  }
  
  .backspace {
    background: linear-gradient(to right, #36d1dc, #5b86e5);
  }
  
  .backspace:hover {
    background: linear-gradient(to right, #5b86e5, #36d1dc);
  }