/* ============================================================
   .uk-site-nav — proposed canonical top navigation (loaded only on /docs/ui-kit)
   ============================================================
   Replaces the legacy declarations in style.css:
     .nav + .nav.scrolled         -> .uk-site-nav + .uk-site-nav.scrolled
     .nav-container               -> .uk-site-nav-container
     .logo + .logo-img            -> .uk-logo + .uk-logo-img
     .logo-icon + .logo-text      -> dropped (unused legacy)
     .nav-links                   -> .uk-site-nav-links
     .nav-link + .active + ::after underline
                                  -> .uk-site-nav-link + --active
     .nav-link-icon               -> .uk-site-nav-link--icon
     .nav-actions                 -> .uk-site-nav-actions
     .mobile-menu-btn + .active   -> .uk-site-nav-toggle + --active

   The canonical .uk-site-nav bakes in every polish detail directly — no
   separate modifier needed:
     - spring cubic-bezier(0.16, 1, 0.3, 1) easing on the underline
     - subtle text-color lift on hover before the underline lands
     - scrolled state compacts padding (md -> sm), intensifies blur
       (12px -> 20px), tints bottom border with primary glow

   Composes with .uk-btn-primary + .uk-btn-ghost (Buttons section)
   inside .uk-site-nav-actions. Logo (.uk-logo) is also reused inside the
   canonical .uk-footer (single source of truth for the wordmark+arc).

   No radial-gradient. JS contract unchanged: an existing scroll listener
   adds .scrolled past a threshold; the toggle button toggles .active
   on .uk-site-nav-toggle and the external drawer.
   ============================================================ */

/* ============================================
   Root — fixed top bar with backdrop blur
   ============================================ */
.uk-site-nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    padding: var(--space-md) 0;
    background: rgba(var(--color-bg-rgb), 0.85);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid transparent;
    transition: padding var(--transition-base),
                background-color var(--transition-base),
                backdrop-filter var(--transition-base),
                border-color var(--transition-base);
}

/* JS-emitted state class — main.js uses `nav.classList.toggle('scrolled', ...)`.
   Migration to canonical is pure CSS rename; the .scrolled hook is preserved. */
.uk-site-nav.scrolled {
    padding: var(--space-sm) 0;
    background: rgba(var(--color-bg-rgb), 0.92);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom-color: rgba(var(--color-primary-rgb), 0.1);
}

/* ============================================
   Container — max-width column with flex layout
   ============================================ */
.uk-site-nav-container {
    max-width: 1280px;
    margin: 0 auto;
    padding: 0 var(--space-lg);
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--space-xl);
}

/* ============================================
   Logo — wordmark + arc lockup link
   Shared canonical: .uk-footer also uses .uk-logo + .uk-logo-img.
   ============================================ */
.uk-logo {
    display: inline-flex;
    align-items: center;
    gap: var(--space-sm);
    text-decoration: none;
    color: var(--color-text);
}

.uk-logo-img {
    display: block;
    height: 32px;
    width: auto;
}

/* ============================================
   Nav links cluster
   ============================================ */
.uk-site-nav-links {
    display: flex;
    align-items: center;
    gap: var(--space-xl);
}

/* ============================================
   Single nav link with animated underline (spring easing).
   ============================================ */
.uk-site-nav-link {
    position: relative;
    color: var(--color-text-secondary);
    text-decoration: none;
    font-size: var(--font-md);
    font-weight: 500;
    transition: color 0.2s cubic-bezier(0.16, 1, 0.3, 1);
}

.uk-site-nav-link::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--gradient-primary);
    border-radius: var(--radius-full);
    transition: width 0.3s cubic-bezier(0.16, 1, 0.3, 1);
}

.uk-site-nav-link:hover,
.uk-site-nav-link--active {
    color: var(--color-text);
}

.uk-site-nav-link:hover::after,
.uk-site-nav-link--active::after {
    width: 100%;
}

/* Icon-only nav link variant (compact, no underline, e.g. external-link arrow) */
.uk-site-nav-link--icon {
    display: inline-flex;
    align-items: center;
    margin-left: calc(-1 * var(--space-xl) + 4px);
    opacity: 0.5;
    transition: opacity var(--transition-fast);
}

.uk-site-nav-link--icon::after {
    display: none;
}

.uk-site-nav-link--icon:hover {
    opacity: 1;
}

/* ============================================
   Actions cluster — sign-in / start-free CTAs
   Buttons inside compose with .uk-btn-primary / .uk-btn-ghost.
   ============================================ */
.uk-site-nav-actions {
    display: flex;
    align-items: center;
    gap: var(--space-md);
}

/* ============================================
   Mobile toggle — burger button morphing to X on .--active
   ============================================ */
.uk-site-nav-toggle {
    display: none;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
    width: 32px;
    height: 32px;
    padding: 4px;
    background: transparent;
    border: 0;
    cursor: pointer;
}

.uk-site-nav-toggle span {
    display: block;
    width: 100%;
    height: 2px;
    background: var(--color-text);
    border-radius: var(--radius-full);
    transition: var(--transition-base);
}

/* JS-emitted state class — main.js uses `mobileMenuBtn.classList.toggle('active')`.
   Migration to canonical is pure CSS rename; the .active hook is preserved. */
.uk-site-nav-toggle.active span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
}

.uk-site-nav-toggle.active span:nth-child(2) {
    opacity: 0;
}

.uk-site-nav-toggle.active span:nth-child(3) {
    transform: rotate(-45deg) translate(5px, -5px);
}

/* ============================================
   Responsive — drop link cluster + actions, surface toggle below 768px
   ============================================ */
@media (max-width: 768px) {
    .uk-site-nav-links,
    .uk-site-nav-actions {
        display: none;
    }

    .uk-site-nav-toggle {
        display: flex;
    }
}

/* ============================================
   Reduced motion
   ============================================ */
@media (prefers-reduced-motion: reduce) {
    .uk-site-nav,
    .uk-site-nav-link,
    .uk-site-nav-link::after,
    .uk-site-nav-link--icon,
    .uk-site-nav-toggle span {
        transition: none;
    }
}