body {
    margin: 0;
    font-family: 'Segoe UI', sans-serif;
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    background: linear-gradient(-45deg, #ff6f61, #6a11cb, #2575fc, #43e97b);
    background-size: 400% 400%;
    animation: gradientBG 12s ease infinite;
}

@keyframes gradientBG {
    0% {background-position: 0% 50%;}
    50% {background-position: 100% 50%;}
    100% {background-position: 0% 50%;}
}

.login-container {
    background: rgba(255, 255, 255, 0.9);
    padding: 30px;
    border-radius: 12px;
    box-shadow: 0 8px 20px rgba(0,0,0,0.3);
    text-align: center;
    width: 90%;           /* antes era fijo en 300px */
    max-width: 350px;     /* límite para pantallas grandes */
}

.login-container h2 {
    margin-bottom: 20px;
    color: #333;
    font-size: 1.5em;     /* tamaño relativo */
}

.login-container input {
    width: 100%;
    padding: 12px;
    margin: 10px 0;
    border: none;
    border-radius: 8px;
    background: #f0f0f0;
    font-size: 1em;
}

.login-container button {
    width: 100%;
    padding: 12px;
    background: linear-gradient(135deg, #4CAF50, #2E7D32);
    border: none;
    border-radius: 8px;
    color: white;
    font-size: 1em;
    cursor: pointer;
    transition: 0.3s;
}

.login-container button:hover {
    background: linear-gradient(135deg, #66BB6A, #388E3C);
}

.error {
    color: red;
    font-size: 0.9em;
    margin-bottom: 10px;
}

/* 📱 Responsividad con media queries */
@media (max-width: 600px) {
    .login-container {
        padding: 20px;
        width: 95%;
    }

    .login-container h2 {
        font-size: 1.2em;
    }

    .login-container input,
    .login-container button {
        font-size: 0.9em;
        padding: 10px;
    }
}