/* BOTONES */
      .salida {
        height: 50px;
        width: 158px;
        margin-bottom: 10px;
        text-align: center;
        font-weight: bold;
        font-family: Verdana, Geneva, Tahoma, sans-serif;
        background-color: lightblue;
        font-size: 20px;
        /* border-color: brown; */
        border:3px solid darkblue;
    }
    
    .keys {
        width: 250px;
    }
    
    .btn,
    .igual{
        width: 50px;
        height: 50px;
        margin-bottom: 5px;
        /* font-size: xx-large; */
        font-weight: bold;
        font-family: Arial, Helvetica, sans-serif;
          background-color: lightcoral;
    }

    .igual:hover{
          background-color: rgba(0, 0, 0, .5);
    }

    .operator {
        width: 50px;
        height: 50px;
        margin-bottom: 5px;
        background-color: turquoise;
        font-weight: bold;
        font-family: Verdana, Geneva, Tahoma, sans-serif;
        border-radius: 50%;
    }
    .operator:hover{
        opacity: 0.75;
        -moz-opacity: .75;
        filter:alpha (opacity=75);
        
    }