html, body {
    background: linear-gradient(#e66465, #9198e5);
    height: 100%;
}
  
  .calc {
    width: 272px;
    margin: 80px auto;
    background: #4C4C4E;
    background-image: linear-gradient(to left, #4C4C4E, 95%, #535355, #4C4C4E);
    padding: 15px;
    border-radius: 6px;
    border: 1px solid #2B2B2B;
    box-shadow: 1px 1px 6px rgba(0,0,0,0.7), -1px -1px 6px rgba(0,0,0,0.3);
  }
  
  .window {
    height: 1.5em;
    line-height: 1.5em;
    width: 100%;
    background: #4D5C3D;
    box-sizing: border-box;
    border: 2px solid rgba(0, 0, 0, 0.7);
    border-right-width: 1px;
    border-bottom-width: 1px;
    color: #000;
    text-align: right;
    padding: 0 10px;
    margin-bottom: 5px;
    font-size: 2em;
    overflow: hidden;
    border-radius: 6px;
  }
  
  .btn {
    margin: 4px 0 0 0;
    display: inline-block;
    width: 64.75px;
    height: 50px;
    line-height: 46px;
    text-align: center;
    border: 0;
    font-size: 1em;
    border-radius: 3px;
    background: #737373;
    color: #fff;
  }
  
  .btn:hover {
    cursor: pointer;
    transition: 0.3s ease-in-out;
    transform: scale(0.8);
  }
  
  #equals {
    width: 133px;
    background-color: #000000;
  }

  #minus, #plus, #divide, #multiply, #square {
      background-color: #0000FF;
  }

  #title {
      margin-left: 30px;
      color: white;
  }

  .ce {
    width: 133px;
    background: linear-gradient(red, #f49242);
  }