:root {
    --text-xs: clamp(0.75rem, 0.7rem + 0.25vw, 0.875rem);
    --text-sm: clamp(0.875rem, 0.8rem + 0.35vw, 1rem);
    --text-base: clamp(1rem, 0.95rem + 0.25vw, 1.125rem);

    --space-2: 0.5rem;
    --space-3: 0.75rem;
    --space-4: 1rem;
    --space-5: 1.25rem;
    --space-6: 1.5rem;
    --space-8: 2rem;
    --space-10: 2.5rem;

    --color-bg: #f5f7fa;
    --color-surface: #ffffff;
    --color-border: oklch(from #1f2933 l c h / 0.12);
    --color-border-subtle: oklch(from #1f2933 l c h / 0.07);
    --color-text: #1f2933;
    --color-text-muted: #555e6b;
    --color-text-faint: #888f99;

    --color-error-text: #9b1c1c;
    --color-error-bg: #fef2f2;
    --color-error-border: oklch(from #9b1c1c l c h / 0.25);

    --radius-sm: 0.25rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.625rem;

    --shadow-card:
            0 1px 3px oklch(0.2 0.01 240 / 0.06),
            0 10px 28px oklch(0.2 0.01 240 / 0.09);

    --transition: 180ms cubic-bezier(0.16, 1, 0.3, 1);
}

*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    -webkit-text-size-adjust: 100%;
    text-size-adjust: 100%;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Arial, sans-serif;
    font-size: var(--text-base);
    line-height: 1.6;
    color: var(--color-text);
    background-color: var(--color-bg);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    display: flex;
    flex-direction: column;
    min-height: 100dvh;
}

img, picture, video, canvas, svg {
    display: block;
    max-width: 100%;
    height: auto;
}

a {
    color: inherit;
}

main {
    flex: 1;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: var(--space-5);
}

.login-card {
    background: var(--color-surface);
    padding: var(--space-10) var(--space-8);
    border-radius: var(--radius-lg);
    width: 100%;
    max-width: 420px;
    text-align: center;
    box-shadow: var(--shadow-card);
    border: 1px solid var(--color-border-subtle);
}

.login-card h2 {
    font-size: clamp(1.5rem, 1.2rem + 0.8vw, 1.9rem);
    line-height: 1.15;
    margin-bottom: var(--space-2);
}

.login-card > p {
    color: var(--color-text-muted);
    font-size: var(--text-sm);
}

.login-methods {
    display: flex;
    flex-direction: column;
    gap: var(--space-3);
    margin: var(--space-6) 0;
}

.idp-buttons {
    display: flex;
    flex-direction: column;
    gap: var(--space-3);
}

.btn-italia {
    display: block;
    text-decoration: none;
    border-radius: 4px;
    overflow: hidden;
    line-height: 0;
    transition: transform var(--transition), box-shadow var(--transition), filter var(--transition);
}

.btn-italia:hover {
    transform: translateY(-1px);
    box-shadow: 0 4px 10px oklch(0.2 0.01 240 / 0.12);
}

.btn-italia:active {
    transform: translateY(0);
    filter: brightness(0.98);
}

.btn-italia:focus-visible,
.btn-google:focus-visible,
.register-button:focus-visible {
    outline: 3px solid #ffdd00;
    outline-offset: 2px;
}

.btn-italia-full {
    display: block;
    width: 100%;
    height: auto;
    max-height: 60px;
    object-fit: contain;
}

.btn-google {
    display: flex;
    align-items: center;
    background-color: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    min-height: 48px;
    text-decoration: none;
    cursor: pointer;
    transition: background-color var(--transition), box-shadow var(--transition), transform var(--transition);
}

.btn-google:hover {
    background-color: #f8f9fa;
    box-shadow: 0 2px 8px oklch(0.2 0.01 240 / 0.12);
}

.btn-google:active {
    background-color: #f1f3f4;
    transform: translateY(1px);
}

.google-icon-wrapper {
    width: 48px;
    min-width: 48px;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
    border-right: 1px solid var(--color-border);
}

.google-icon {
    width: 18px;
    height: 18px;
    object-fit: contain;
}

.btn-text-google {
    flex: 1;
    text-align: center;
    padding-right: 48px;
    color: #3c4043;
    font-weight: 500;
    font-size: var(--text-sm);
    white-space: nowrap;
}

.separator {
    display: flex;
    align-items: center;
    gap: var(--space-3);
    color: var(--color-text-faint);
    font-size: var(--text-xs);
    letter-spacing: 0.04em;
    text-transform: uppercase;
    margin: var(--space-5) 0;
}

.separator::before,
.separator::after {
    content: "";
    flex: 1;
    height: 1px;
    background: var(--color-border-subtle);
}

.register-cta {
    margin-top: var(--space-6);
    text-align: center;
}

.register-cta p {
    margin-bottom: var(--space-2);
    font-size: var(--text-sm);
    color: var(--color-text-muted);
}

.register-button {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: var(--space-2) var(--space-5);
    border-radius: var(--radius-md);
    border: 1px solid var(--color-text);
    color: var(--color-text);
    text-decoration: none;
    font-size: var(--text-sm);
    font-weight: 500;
    transition: background-color var(--transition), color var(--transition), border-color var(--transition);
}

.register-button:hover {
    background-color: var(--color-text);
    color: #ffffff;
}

.register-button:active {
    background-color: #111820;
    color: #ffffff;
}

.login-error {
    margin-top: var(--space-3);
    color: var(--color-error-text);
    font-size: var(--text-sm);
    font-weight: 600;
    text-align: center;
    background-color: var(--color-error-bg);
    padding: var(--space-3) var(--space-4);
    border-radius: var(--radius-md);
    border: 1px solid var(--color-error-border);
}

.hidden {
    display: none !important;
}

@media (max-width: 480px) {
    main {
        padding: var(--space-4);
    }

    .login-card {
        padding: var(--space-8) var(--space-5);
    }
}