* {
    margin: 0px;
    padding: 0px;
    box-sizing: border-box;
    background-color: #696969;  
    font-family: sans-serif;
    outline: none;
  }
  
  .container {
      height: 100vh;
      display: flex;
      justify-content: center;
      align-items: center;
  }
  
  .calculator {
      background-color: #C0C0C0;
      padding: 15px;
      border-radius: 30px;
      box-shadow: inset 5px 5px 12px #ffffff, 5px 5px 12px rgba(0, 0, 0, 0.16);
      display: grid;
      grid-template-columns: repeat(4, 68px);
  }
  
  input {
      grid-column: span 4;
      height: 70px;
      width: 260px; 
      background-color: #FFFFFF;
      box-shadow: inset -5px -5px 12px #C0C0C0, inset 5px 5px 12px rgba(0, 0, 0, 0.16);
      border: none;
      border-radius: 30px;
      color: rgb(70, 70, 70);
      font-size: 50px;
      text-align: end;
      margin-top: 40px;
      margin-bottom: 30px;
      padding: 20px;
  }
  
  button {
      height: 48px;
      width: 48px;
      background-color: #C0C0C0;
      box-shadow: -5px -5px 12px #696969, 5px 5px 12px rgba(0, 0, 0, 0.16);
      border: none;
      border-radius: 50%;
      margin: 8px;
      font-size: 16px;
      font-weight: bold;
  }
  
  .equal {
      width: 115px;
      border-radius: 40px;
  }