body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    background: linear-gradient(to bottom, #1e1e1e, #3a3a3a);
    font-family: "SF Pro", sans-serif;
    margin: 0;
  }
  
  .calc {
    width: 340px;
    background: #2c2c2e;
    border-radius: 20px;
    padding: 20px;
    box-shadow: 0px 10px 30px rgba(0, 0, 0, 0.6);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 15px;
  }
  
  #screen {
    width: 95%;
    height: 70px;
    background: #1c1c1e;
    color: white;
    font-size: 3rem;
    text-align: right;
    padding: 15px;
    border-radius: 15px;
    margin-bottom: 10px;
    box-shadow: inset 0px 0px 10px rgba(0, 0, 0, 0.5);
    font-weight: bold;
    border: 1px solid rgba(255, 255, 255, 0.1);
  }
  
  .row {
    display: flex;
    justify-content: space-between;
    width: 100%;
    gap: 10px;
  }
  
  button {
    flex: 1;
    height: 70px;
    font-size: 1.8rem;
    font-weight: bold;
    border: none;
    border-radius: 15px;
    background: #3d3d3d;
    color: white;
    box-shadow: 0px 4px 10px rgba(0, 0, 0, 0.4);
    cursor: pointer;
    transition: all 0.2s ease-in-out;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    overflow: hidden;
  }
  
  #0 {
    flex: 2;
  }
  
  button:active {
    transform: scale(0.95);
    box-shadow: 0px 2px 5px rgba(0, 0, 0, 0.6);
  }
  
  #clear,
  #plusminus,
  #pi {
    background: #a5a5a5;
    color: black;
  }
  
  #equals,
  #addition,
  #subtraction,
  #multiplication,
  #division {
    background: #ff9500;
    color: white;
  }
  
  button:hover {
    filter: brightness(1.2);
  }
  
  button:active::before {
    content: "";
    position: absolute;
    width: 100%;
    height: 100%;
    background: rgba(255, 255, 255, 0.2);
    border-radius: 15px;
    animation: glow 0.3s ease-out;
  }
  
  @keyframes glow {
    from {
      transform: scale(1);
      opacity: 0.5;
    }
    to {
      transform: scale(1.5);
      opacity: 0;
    }
  }
  
  @media (max-width: 400px) {
    .calc {
      width: 300px;
      padding: 15px;
    }
    button {
      height: 60px;
      font-size: 1.6rem;
    }
    #screen {
      font-size: 2.5rem;
      height: 90px;
    }
  }