/* --- Navigation --- */
.nav-header {
    position: sticky;
    top: 0;
    width: 100%;
    height: 72px;
    background-color: var(--color-header-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    z-index: 100;
    border-bottom: 1px solid var(--color-border);
}

.nav-container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 var(--padding-x-mobile);
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

@media (min-width: 768px) {
    .nav-container {
        padding: 0 var(--padding-x-desktop);
    }
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: 12px;
    font-family: var(--font-display);
    font-size: 1.125rem; /* 18px */
    font-weight: 500;
    color: var(--color-ink);
}

.logo-mark {
    color: var(--color-signal);
}

.nav-links {
    display: none; /* Hidden on mobile by default */
    list-style: none;
    gap: 32px;
}

@media (min-width: 768px) {
    .nav-links {
        display: flex;
    }
}

.nav-links a {
    font-family: var(--font-body);
    font-size: 0.875rem; /* 14px */
    color: var(--color-ink-muted);
    transition: color var(--transition-base);
}

.nav-links a:hover {
    color: var(--color-ink);
}

.nav-links--mobile-open {
    display: flex !important;
    flex-direction: column;
    position: absolute;
    top: 72px;
    left: 0;
    width: 100%;
    background-color: var(--color-bg);
    padding: 24px;
    border-bottom: 1px solid var(--color-border);
}

/* Hide the header CTA button on mobile */
@media (max-width: 767px) {
    .nav-actions .nav-cta {
        display: none;
    }
}

/* CTA in mobile menu: hidden until menu is open */
.nav-cta-mobile {
    display: none;
}

.nav-links--mobile-open .nav-cta-mobile {
    display: block;
    margin-top: 8px;
    padding-top: 16px;
    border-top: 1px solid var(--color-border);
}

.nav-cta-mobile .btn {
    width: 100%;
    justify-content: center;
}

.nav-actions {
    display: flex;
    align-items: center;
    gap: 16px;
}

.theme-toggle {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    min-width: 0;
    height: 40px;
    padding: 4px 6px 4px 14px;
    border: 1px solid var(--color-border);
    border-radius: 999px;
    background-color: var(--color-surface-elevated);
    color: var(--color-ink);
    cursor: pointer;
    transition: background-color var(--transition-base), border-color var(--transition-base), color var(--transition-base), transform var(--transition-base);
}

.theme-toggle:hover {
    border-color: color-mix(in srgb, var(--color-signal) 32%, var(--color-border));
}

.theme-toggle:active {
    transform: translateY(1px);
}

.theme-toggle-mode {
    font-family: var(--font-body);
    font-size: 0.8125rem;
    font-weight: 500;
    color: var(--color-toggle-label);
}

.theme-toggle-track {
    position: relative;
    width: 42px;
    height: 24px;
    border-radius: 999px;
    background-color: var(--color-toggle-track);
    transition: background-color var(--transition-base);
}

.theme-toggle-thumb {
    position: absolute;
    top: 3px;
    left: 3px;
    width: 18px;
    height: 18px;
    border-radius: 50%;
    background-color: var(--color-toggle-thumb);
    box-shadow: 0 2px 8px color-mix(in srgb, var(--color-ink) 14%, transparent);
    transition: transform var(--transition-base), background-color var(--transition-base);
}

.theme-toggle[aria-pressed="true"] .theme-toggle-thumb {
    transform: translateX(18px);
    background-color: var(--color-signal);
}

.about-header-actions {
    display: flex;
    align-items: center;
    gap: 12px;
}

.about-back-link {
    background-color: var(--color-surface);
    border: 1px solid var(--color-border);
    color: var(--color-ink);
    font-size: 0.875rem;
    font-family: var(--font-body);
    font-weight: 500;
    padding: 8px 16px;
    border-radius: 99px;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: 6px;
    transition: background-color var(--transition-base), border-color var(--transition-base), color var(--transition-base);
}

.about-back-link:hover {
    background-color: var(--color-surface-elevated);
}

.about-back-icon {
    width: 16px;
    height: 16px;
    color: var(--color-ink-muted);
}

.mobile-menu-toggle {
    display: block;
    background: none;
    border: none;
    color: var(--color-ink);
    cursor: pointer;
}

@media (min-width: 768px) {
    .mobile-menu-toggle {
        display: none;
    }
}

@media (max-width: 640px) {
    .theme-toggle {
        padding-left: 10px;
    }

    .theme-toggle-mode,
    .about-back-label {
        display: none;
    }

    .nav-actions {
        gap: 10px;
    }
}

/* --- Buttons --- */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    font-family: var(--font-body);
    font-size: 1rem;
    font-weight: 500;
    text-decoration: none;
    border-radius: 4px; /* Slight rounding, calm */
    transition: all var(--transition-base);
    cursor: pointer;
}

.btn-outline-signal {
    height: 36px;
    padding: 0 16px;
    font-size: 0.875rem; /* 14px */
    color: var(--color-signal);
    border: 1px solid var(--color-signal);
    background: transparent;
}

.btn-outline-signal:hover {
    background: var(--color-signal-lt);
}

.btn-primary-signal {
    height: 48px;
    padding: 0 24px;
    background-color: var(--color-signal);
    color: var(--color-signal-contrast);
    border: none;
}

.btn-primary-signal:hover {
    background-color: var(--color-signal-hover);
}

.btn-text-muted {
    height: 48px;
    padding: 0 16px;
    color: var(--color-ink-muted);
    background: transparent;
    border: none;
}

.btn-text-muted:hover {
    color: var(--color-ink);
}

/* --- Brand & Logo --- */
.nav-brand-link {
    display: flex;
    align-items: center;
    gap: 8px;
    text-decoration: none;
}

.nav-brand-logo {
    width: 24px;
    height: 24px;
    border-radius: 50%;
    object-fit: contain;
}

.nav-brand-text {
    font-family: var(--font-display);
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--color-ink);
    letter-spacing: -0.02em;
}

.footer-brand-link {
    display: flex;
    align-items: center;
    gap: 8px;
    text-decoration: none;
}

.footer-brand-logo {
    width: 32px;
    height: 32px;
    border-radius: 50%;
    object-fit: cover;
}

.footer-brand-text {
    font-family: var(--font-display);
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--color-ink);
    letter-spacing: -0.02em;
}

.footer-desc {
    color: var(--color-ink-muted);
    font-size: 0.875rem;
    line-height: 1.6;
    margin-bottom: 24px;
}