body {
    background: url('../img/login_bg.jpg') no-repeat center center fixed;
    background-size: cover;
    display: flex;
    align-items: center;
    justify-content: center;
    height: 100vh;
    margin: 0;
    font-family: 'Segoe UI', Tahoma, sans-serif;
}

.login-card {
    background: rgba(255, 255, 255, 0.92);
    padding: 40px;
    border-radius: 10px;
    width: 100%;
    max-width: 360px;
    box-shadow: 0 0 20px rgba(0,0,0,0.3);
}

.login-card h4 {
    text-align: center;
    margin-bottom: 20px;
    color: #333;
    font-weight: 600;
}

/* === Ajustes móviles === */
@media (max-width: 576px) {
    body {
        align-items: flex-start; /* un poco más arriba en móviles */
        padding-top: 40px;
    }

    .login-card {
        padding: 50px 30px;
        max-width: 95%; /* casi todo el ancho */
    }

    .login-card h4 {
        font-size: 1.8rem;
    }

    .form-control {
        font-size: 1.2rem;
        padding: 0.8rem;
    }

    .btn {
        font-size: 1.2rem;
        padding: 0.8rem;
    }
}