body {
    background: #e9ecef;
}
.login-box {
    max-width: 450px;
    margin: 80px auto;
    background: #fff;
    border-radius: 10px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.1);
    padding: 35px;
}
h2 {
    text-align: center;
    margin-bottom: 25px;
    color: #333;
}
.btn-primary {
    width: 100%;
}
.alert {
    text-align: center;
}