body {
    font-family: Arial;
    background: #f0f0f0;
}

.box {
    width: 310px;
    margin: 70px auto;
    background: #fff;
    padding: 25px;
    box-shadow: 0 0 10px rgba(0,0,0,.1);
}

input,
button {
    width: 100%;
    padding: 10px;
    margin-top: 10px;
    box-sizing: border-box;
}

.error {
    color: red;
}