html,
body {
    height: 100%;
}

body {
    display: -ms-flexbox;
    display: flex;
    -ms-flex-align: center;
    align-items: center;
    background-color: #f5f5f5;
}

section {
    width: 100%;
    height: 100%;
}

.form-signin {
    width: 100%;
    max-width: 330px;
    padding: 15px;
    margin: auto;
}