html,
body {
  height: 100%;
}
body {
  display: -ms-flexbox;
  display: flex;
  -ms-flex-align: center;
  align-items: center;
  padding-top: 40px;
  padding-bottom: 40px;
  background-color: #f5f5f5;
}
.form-central {
  width: 100%;
  max-width: 420px;
  padding: 15px;
  margin: auto;
}
body {
	background-image: url('bg.jpg');
	background-size: cover;
	background-repeat: no-repeat;
}