html,
body {
    height: 100%;
}

body {
    display: flex;
    align-items: center;
    -ms-flex-align: center;
    padding-top: 40px;
    padding-bottom: 40px;
    background-color: #f5f5f5;
}

.form-signin .form-control:focus {
    z-index: 2;
}