output {
          width:            138px;
          font-size:        12px;
          background-color: white;
          text-align:       right;
          border:           1px;
          margin: 2px 2px 2px 2px;
          border-style:     solid;
          border-width:     thin;
        }
        
        group {
          width:            144px;

        }
        
        trigger {
          width:            30px;
          font-size:        12px;
          border-style:     solid;
          border-width:     thin;
          background-color: white;
          margin: 2px 2px 2px 2px;
          text-align:       center;
          padding: 0px;
        }
        
        .number {
            color: blue;
        }
        
        trigger:hover {
            background-color: #D0D0D0;
        }
        
        trigger:active {
            background-color: #D0D0D0;
            border-style:     outset;
        }
        
        #zero {
          width:            66px;                    
        }
        
        .operator {
            color: red;
        }
        
        .function {
            color: darkGray;
        }