*{
  font-size:20px;
}
#calc-div {
    position: absolute;
    top:30%;
    left:50%;
    z-index: 9;
    background-color: #f1f1f1;
    border: 1px solid #808080;
    text-align: center;
    width:600px;
  }
  #calc-div-header {
    padding: 0px;
    cursor: move;
    z-index: 10;
    background-color: #808080;
    color: white;
    height: 25px;
  }
  #close-calc{
    position:absolute;
    cursor:pointer;
    top:0px;
    right: 0px;
    height: 25px;
    width: 25px;
    background-color:red;
  }
  table{
    width:600px;
    height:auto;
    border: 1px solid #808080;
    padding: 0;
    margin: 0;
  }
  tr{
    width:600px;
    text-align:center;
    padding: 0;
    margin: 0;
  }
  td{
    width:100px;
    height:35px;
    border: 1px solid #808080;
    padding: 0;
    margin: 0;
  }
  .cell{
    
    height:35px;
    border: 1px solid #808080;
    padding: 0;
    margin: 0;
  }
  .a{
    color:blue; /* Green background */
    font-size:15px;
  }
  button{
    width:100%;
    height:100%;
    padding:0;
    margin:0;
    
  }
  #calculatorWindow{
    -moz-appearance: textfield; /* Firefox */
  appearance: textfield; /* Chrome, Safari, Edge */
  height:35px;
  font-size:20px;
  }