body {
    font-family: Arial, sans-serif;
    background-color: #f0f2f5;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
}
.login-container {
    width: 100%;
    max-width: 400px;
    padding: 2rem;
}
.login-form {
    background: #fff;
    padding: 2.5rem;
    border-radius: 12px;
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.1);
    text-align: center;
}
.login-form h2 {
    margin-bottom: 0.5rem;
    color: #333;
    font-size: 1.8rem;
}
.login-form p {
    margin-bottom: 2rem;
    color: #666;
}
.form-group {
    margin-bottom: 1.5rem;
    text-align: left;
}
.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
    color: #555;
}
.form-group input {
    width: 100%;
    padding: 0.8rem;
    border: 1px solid #ddd;
    border-radius: 6px;
    box-sizing: border-box; /* Important for padding */
}
button {
    width: 100%;
    padding: 0.9rem;
    border: none;
    border-radius: 6px;
    background-color: #007bff;
    color: white;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.3s ease;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 48px; /* Cho spinner */
}
button:hover {
    background-color: #0056b3;
}
button:disabled {
    background-color: #a0cffc;
    cursor: not-allowed;
}

/* Spinner (Tái sử dụng từ css/style.css) */
.spinner {
    width: 20px;
    height: 20px;
    border: 3px solid rgba(255, 255, 255, 0.3);
    border-radius: 50%;
    border-top-color: #fff;
    animation: spin 1s ease-in-out infinite;
}
.hidden { display: none; }
@keyframes spin {
    to { transform: rotate(360deg); }
}