/* ============================================================
   AIxcel Labs — Global Layout & Base Styles  (css/main.css)
   ============================================================
   Depends on: tokens.css, reset.css
   Provides:   page shell, skip link, sticky navbar, mobile
               drawer, footer, containers, section helpers,
               prose block, theme toggle, skeleton loader,
               visually-hidden utility, dark-mode overrides.
   ============================================================ */

/* ── PAGE SHELL ─────────────────────────────────────────────── */
body {
  display: flex;
  flex-direction: column;
}

/* Push footer to bottom on short pages */
main {
  flex: 1 0 auto;
}

/* ── SKIP TO MAIN CONTENT ───────────────────────────────────── */

/* First focusable element on every page — keyboard accessibility */
.skip-link {
  position: absolute;
  inset-inline-start: var(--space-4);
  inset-block-start:  var(--space-4);
  z-index: var(--z-tooltip);
  padding: var(--space-2) var(--space-4);
  background:   var(--bg-dark);
  color:        var(--text-inverse);
  font-size:    var(--text-sm);
  font-weight:  var(--font-semibold);
  border-radius: var(--radius-md);
  text-decoration: none;
  white-space: nowrap;

  /* Hidden by default; visible on keyboard focus */
  transform: translateY(-200%);
  transition: transform var(--transition-fast);
}

.skip-link:focus-visible {
  transform: translateY(0);
  outline: 2px solid var(--cyan-300);
  outline-offset: 2px;
}

/* ── NAVBAR ─────────────────────────────────────────────────── */
.navbar {
  position: sticky;
  inset-block-start: 0;
  z-index: var(--z-sticky);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-6);
  height: var(--navbar-height);
  padding-inline: var(--container-padding);

  /* Force dark theme on navbar regardless of device preference */
  color-scheme: dark;

  /* Frosted glass effect — always dark */
  background-color: color-mix(in srgb, var(--bg-dark) 95%, transparent);
  backdrop-filter: blur(12px);
  border-block-end: 1px solid var(--cyan-700);
  transition: background-color var(--transition-base),
              border-color      var(--transition-base);
}

.navbar-brand {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  text-decoration: none;
  color: var(--text-on-dark);
  font-weight: var(--font-bold);
  font-size: var(--text-lg);
  flex-shrink: 0;
}

.navbar-brand img,
.navbar-brand svg {
  height: 56px;
  width: auto;
}

.brand-logo {
  display: block;
  inline-size: auto;
  block-size: 56px;
}

.brand-logo-header {
  block-size: clamp(52px, 6vw, 64px);
}

.brand-logo-footer {
  block-size: clamp(56px, 6vw, 72px);
}

/* Desktop nav links — hidden on mobile */
.navbar-nav {
  display: none;
  align-items: center;
  gap: var(--space-1);
}

@media (width >= 768px) {
  .navbar-nav {
    display: flex;
  }
}

.nav-link {
  font-size:    var(--text-sm);
  font-weight:  var(--font-medium);
  color:        var(--text-on-dark-muted);
  padding:      var(--space-2) var(--space-3);
  border-radius: var(--radius-md);
  text-decoration: none;
  white-space: nowrap;
  transition: color var(--transition-fast),
              background-color var(--transition-fast);
}

.nav-link:hover {
  color: var(--text-on-dark);
  background-color: var(--cyan-800);
}

.nav-link[aria-current="page"],
.nav-link.active {
  color: var(--cyan-200);
  background-color: var(--cyan-900);
}

/* Navbar right-side actions (CTA, theme toggle) */
.navbar-actions {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

/* Hamburger toggle — visible only on mobile */
.navbar-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-2);
  color: var(--text-on-dark-muted);
  border-radius: var(--radius-md);
  cursor: pointer;
  border: none;
  background: none;
  transition: color var(--transition-fast),
              background-color var(--transition-fast);
}

.navbar-toggle:hover {
  color: var(--text-on-dark);
  background-color: var(--cyan-800);
}

@media (width >= 768px) {
  .navbar-toggle {
    display: none;
  }
}

/* Mobile drawer */
.navbar-mobile-menu {
  display: none;
  position: fixed;
  inset: var(--navbar-height) 0 0 0;
  z-index: var(--z-overlay);
  background-color: var(--bg-page);
  border-block-start: 1px solid var(--border-default);
  padding: var(--space-6) var(--container-padding);
  overflow-y: auto;
  flex-direction: column;
  gap: var(--space-2);
}

.navbar-mobile-menu.is-open {
  display: flex;
}

@media (width >= 768px) {
  .navbar-mobile-menu {
    display: none !important;
  }
}

.navbar-mobile-menu .nav-link {
  font-size: var(--text-base);
  padding:   var(--space-3) var(--space-4);
  border-radius: var(--radius-lg);
}

/* ── FOOTER ─────────────────────────────────────────────────── */

/* ── BASE LINK STYLES ───────────────────────────────────────── */
a.link,
.prose a {
  color: var(--text-brand);
  text-decoration: underline;
  text-underline-offset: 3px;
  transition: color var(--transition-fast);
}

a.link:hover,
.prose a:hover {
  color: var(--cyan-700);
}

/* ── FOOTER ─────────────────────────────────────────────────── */
footer {
  background-color: var(--slate-900);
  color: var(--slate-400);
  padding-block: var(--space-16) var(--space-8);
  flex-shrink: 0;
}

.footer-inner {
  width: 100%;
  max-width: var(--container-xl);
  margin-inline: auto;
  padding-inline: var(--container-padding);
}

.footer-top {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-10);
}

@media (width >= 768px) {
  .footer-top {
    grid-template-columns: 2fr 1fr 1fr;
  }
}

.footer-brand {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  color: var(--white);
  font-weight: var(--font-bold);
  font-size: var(--text-lg);
  text-decoration: none;
  margin-block-end: var(--space-4);
}

.footer-brand img,
.footer-brand svg {
  height: 28px;
  width: auto;
}

.footer-tagline {
  font-size: var(--text-sm);
  color: var(--slate-400);
  line-height: var(--leading-relaxed);
}

.footer-heading {
  font-size: var(--text-sm);
  font-weight: var(--font-semibold);
  color: var(--white);
  margin-block-end: var(--space-4);
  letter-spacing: var(--tracking-wider);
  text-transform: uppercase;
}

.footer-links {
  display: flex;
  flex-direction: column;
  gap: var(--space-2-5);
}

/* stylelint-disable-next-line no-descending-specificity -- `.footer-links` and `.prose` never target the same DOM subtree */
.footer-links a {
  font-size: var(--text-sm);
  color: var(--slate-400);
  text-decoration: none;
  transition: color var(--transition-fast);
}

.footer-links a:hover {
  color: var(--white);
}

.footer-bottom {
  margin-block-start: var(--space-12);
  padding-block-start: var(--space-6);
  border-block-start: 1px solid var(--slate-800);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  font-size: var(--text-xs);
  color: var(--slate-500);
}

/* ── CONTAINERS ─────────────────────────────────────────────── */
.container {
  width: 100%;
  max-width: var(--container-xl);
  margin-inline: auto;
  padding-inline: var(--container-padding);
}

.container-sm  { max-width: var(--container-sm);  }
.container-md  { max-width: var(--container-md);  }
.container-lg  { max-width: var(--container-lg);  }
.container-2xl { max-width: var(--container-2xl); }

/* ── SECTIONS ───────────────────────────────────────────────── */

/* Fluid vertical rhythm — adapts between mobile and desktop */
.section {
  padding-block: clamp(3rem, 8vw, 6rem);
}

.section-sm {
  padding-block: clamp(2rem, 5vw, 3.5rem);
}

.section-lg {
  padding-block: clamp(5rem, 12vw, 9rem);
}

/* Dark background variant (e.g. CTAs, hero variants) */
.section-dark {
  background-color: var(--cyan-900);
  color: var(--white);
}

.section-dark h1,
.section-dark h2,
.section-dark h3 {
  color: var(--white);
}

.section-dark p {
  color: var(--cyan-200);
}

/* Alternate surface variant */
.section-surface {
  background-color: var(--bg-surface);
}

/* ── BASE LINK STYLES ───────────────────────────────────────── */

/* ── PROSE / RICH TEXT ──────────────────────────────────────── */
.prose {
  max-width: var(--content-max-width);
}

.prose p + p {
  margin-block-start: var(--space-4);
}

.prose h2,
.prose h3,
.prose h4 {
  margin-block: var(--space-8) var(--space-3);
}

.prose ul,
.prose ol {
  padding-inline-start: var(--space-6);
  list-style: disc;
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}

.prose ol {
  list-style: decimal;
}

.prose li {
  color: var(--text-secondary);
  font-size: var(--text-base);
  line-height: var(--leading-relaxed);
}

/* ── CODE ───────────────────────────────────────────────────── */
code {
  font-family: var(--font-mono);
  font-size: 0.9em;
  background: var(--slate-100);
  padding: 0.1em 0.35em;
  border-radius: var(--radius-sm);
  color: var(--cyan-700);
}

pre {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  background: var(--slate-900);
  color: var(--cyan-200);
  padding: var(--space-6);
  border-radius: var(--radius-lg);
  overflow-x: auto;
  line-height: var(--leading-relaxed);
}

pre code {
  background: none;
  padding: 0;
  color: inherit;
  font-size: inherit;
}

@media (prefers-color-scheme: dark) {
  code {
    background: var(--cyan-900);
    color: var(--cyan-200);
  }
}

:root[data-theme="dark"] code {
  background: var(--cyan-900);
  color: var(--cyan-200);
}

/* ── BLOCKQUOTE ─────────────────────────────────────────────── */
blockquote {
  border-inline-start: 3px solid var(--border-brand);
  padding: var(--space-3) var(--space-5);
  background: var(--bg-brand-subtle);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  color: var(--text-secondary);
  font-style: italic;
}

/* ── HR ─────────────────────────────────────────────────────── */
hr {
  border-block-start: 1px solid var(--border-default);
  margin-block: var(--space-8);
}

/* ── THEME TOGGLE BUTTON ────────────────────────────────────── */
.theme-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 2.25rem;
  height: 2.25rem;
  padding: var(--space-2);
  color: var(--text-secondary);
  border-radius: var(--radius-md);
  border: 1px solid var(--border-default);
  background: var(--bg-raised);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.theme-toggle:hover {
  color: var(--text-primary);
  border-color: var(--border-brand);
  background: var(--bg-brand-subtle);
}

/* ── VISUALLY HIDDEN (accessibility utility) ────────────────── */
.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border-width: 0;
}

/* ── SKELETON LOADER ────────────────────────────────────────── */
@keyframes skeleton-shimmer {
  0%   { background-position: -200% 0; }
  100% { background-position:  200% 0; }
}

.skeleton {
  background: linear-gradient(
    90deg,
    var(--slate-100) 25%,
    var(--slate-50)  50%,
    var(--slate-100) 75%
  );
  background-size: 200% 100%;
  animation: skeleton-shimmer 1.5s infinite;
  border-radius: var(--radius-md);
}

@media (prefers-reduced-motion: reduce) {
  .skeleton {
    animation: none;
    background: var(--slate-100);
  }
}