html,
body,
main {
    height: 100%;
}

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

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

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

.form-signin .form-control {
    position: relative;
    box-sizing: border-box;
    height: auto;
    padding: 10px;
    font-size: 16px;
    outline: none;
}

.btn-block {
    display: block;
    width: 100%;
}

.er {
    height: 2rem;
}