html,
body {
  height: 100%;
}

@media screen and (min-height:400px) and (min-width:400px) {
  .coluna2{
    height: 100%;
  }
  .coluna2 .container{
    height: 100%;
  }
}

body{
  background-color: #f5f5f5;
}

nav{
    color: #ffffff;
}

span.sair:hover{
  color: red;
  cursor: pointer;
}

.coluna2 .container {
  flex-direction: row;
  display: -ms-flexbox;
  display: -webkit-box;
  display: flex;
  -ms-flex-align: center;
  -ms-flex-pack: center;
  -webkit-box-align: center;
  align-items: center;
  -webkit-box-pack: center;
  justify-content: center;
}

.form-signin {
  width: 100%;
  max-width: 420px;
  padding: 15px;
  margin: 0 auto;
}

.form-label-group > label{
  display: none;
}

.form-label-group > input{
  margin-bottom: 1rem;
  padding: 0.75rem;
  font-weight: bold;
}