body {
    margin: 0;
    padding: 0;
    height: 100vh;
    display: flex;
}

@import url(https://fonts.googleapis.com/css?family=Roboto:100);

.center {
    margin: auto;
}

.resultado {
    font-family: 'Open Sans', Arial, Helvetica, sans-serif;
    font-size: 16pt;
    color: #656565;
}


#loading {
    display: inline-block;
    width: 50px;
    height: 50px;
    border: 3px solid rgba(255,255,255,.3);
    border-radius: 50%;
    border-top-color: #37b34a;
    animation: spin 1s ease-in-out infinite;
    -webkit-animation: spin 1s ease-in-out infinite;
  }
  
  @keyframes spin {
    to { -webkit-transform: rotate(360deg); }
  }
  @-webkit-keyframes spin {
    to { -webkit-transform: rotate(360deg); }
  }