/* ============================================================================
   layout.css  —  header, footer, grid utilities, section rhythm
   V3-specific: flat nav, persona tab strip, narrative long-scroll primitives
============================================================================ */

/* ---- Container --------------------------------------------------------- */
.container        { width: 100%; max-width: var(--container-max);  margin-inline: auto; padding-inline: var(--gutter); }
.container--wide  { max-width: var(--container-wide); }
.container--prose { max-width: var(--container-prose); }

/* ---- Section rhythm ---------------------------------------------------- */
.section       { padding-block: var(--section-py); }
.section--large { padding-block: var(--section-py-large); }
.section--tight { padding-block: var(--section-py-tight); }
.section--alt   { background: var(--color-bg-alt); }
.section--dark  {
  background: var(--color-bg-dark);
  color: rgba(255,255,255,0.92);
}
.section--dark h1, .section--dark h2, .section--dark h3,
.section--dark h4, .section--dark h5 { color: #fff; }

/* ---- Stack: vertical spacing ------------------------------------------ */
.stack > * + *       { margin-top: var(--stack-gap, var(--space-4)); }
.stack--tight        { --stack-gap: var(--space-2); }
.stack--loose        { --stack-gap: var(--space-6); }
.stack--xl           { --stack-gap: var(--space-8); }

/* ---- Cluster: horizontal flex row ------------------------------------- */
.cluster               { display: flex; flex-wrap: wrap; gap: var(--space-4); align-items: center; }
.cluster--tight        { gap: var(--space-2); }
.cluster--end          { justify-content: flex-end; }
.cluster--between      { justify-content: space-between; }

/* ---- Grid utilities ---------------------------------------------------- */
.grid    { display: grid; gap: var(--space-5); }
.grid--2 { grid-template-columns: repeat(auto-fit, minmax(min(100%, 18rem), 1fr)); }
.grid--3 { grid-template-columns: repeat(auto-fit, minmax(min(100%, 16rem), 1fr)); }

@media (min-width: 48em) {
  .grid--2-md { grid-template-columns: repeat(2, 1fr); }
  .grid--3-md { grid-template-columns: repeat(3, 1fr); }
}

/* ---- Scroll progress bar ----------------------------------------------- */
.scroll-progress {
  position: fixed;
  top: 0;
  left: 0;
  z-index: var(--z-progress);
  height: var(--scroll-progress-height);
  width: var(--scroll-progress-pct);
  background: var(--color-persona-active, var(--color-accent));
  transition: width 80ms linear;
  pointer-events: none;
}
@media (prefers-reduced-motion: reduce) {
  .scroll-progress { display: none; }
}

/* ---- Site header ------------------------------------------------------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: var(--z-sticky);
  background: color-mix(in srgb, var(--color-bg) 94%, transparent);
  backdrop-filter: saturate(160%) blur(12px);
  -webkit-backdrop-filter: saturate(160%) blur(12px);
  border-bottom: 1px solid var(--color-border);
  transition: box-shadow var(--duration-fast) var(--ease-standard);
}
.site-header--scrolled {
  box-shadow: 0 1px 8px rgba(17,17,17,0.06);
}
.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-5);
  min-height: var(--header-height);
  padding-block: var(--space-2);
}
@media (min-width: 60em) {
  .site-header__inner { min-height: var(--header-height-lg); }
}

/* Brand mark */
.site-header__brand {
  display: inline-flex;
  align-items: center;
  gap: var(--space-3);
  font-weight: var(--font-weight-bold);
  font-size: var(--step-1);
  color: var(--color-fg);
  text-decoration: none;
  letter-spacing: -0.01em;
  flex-shrink: 0;
}
.site-header__brand:hover { color: var(--color-fg); text-decoration: none; }
.site-header__brand img {
  height: 1.75rem;
  width: auto;
  display: block;
}

/* ---- Primary nav ------------------------------------------------------- */
.primary-nav { display: none; }
@media (min-width: 60em) {
  .primary-nav {
    display: flex;
    align-items: center;
    gap: var(--space-1);
    flex: 1;
    justify-content: center;
  }
}
.primary-nav__list {
  display: flex;
  gap: 0;
  list-style: none;
  padding: 0;
  margin: 0;
  align-items: center;
}
.primary-nav__item { position: relative; list-style: none; }

.primary-nav__link {
  display: inline-flex;
  align-items: center;
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius-1);
  color: var(--color-fg-muted);
  text-decoration: none;
  font-weight: var(--font-weight-medium);
  font-size: var(--step--1);
  white-space: nowrap;
  transition: color var(--duration-fast) var(--ease-standard),
              background var(--duration-fast) var(--ease-standard);
}
.primary-nav__link:hover {
  color: var(--color-fg);
  background: var(--color-bg-alt);
  text-decoration: none;
}
.primary-nav__link[aria-current="page"] {
  color: var(--color-fg);
  font-weight: var(--font-weight-semi);
}
/* Dropdown trigger — button reset then inherits link styles */
.primary-nav__link--has-dropdown {
  background: none;
  border: none;
  font-family: inherit;
  gap: var(--space-1);
  cursor: pointer;
}
.primary-nav__chevron {
  width: 10px;
  height: 10px;
  flex-shrink: 0;
  transition: transform var(--duration-fast) var(--ease-standard);
  opacity: 0.55;
}
.primary-nav__link--has-dropdown[aria-expanded="true"] .primary-nav__chevron {
  transform: rotate(180deg);
  opacity: 0.8;
}

/* ---- Dropdown panels --------------------------------------------------- */
.primary-nav__panel {
  display: none;
  position: absolute;
  top: calc(100% + 6px);
  left: 0;
  min-width: 14rem;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-2);
  box-shadow: 0 8px 32px rgba(17,17,17,0.10), 0 2px 6px rgba(17,17,17,0.05);
  z-index: var(--z-overlay);
  padding: var(--space-3);
}
.primary-nav__panel[data-open="true"] { display: block; }
.primary-nav__panel--wide  { min-width: 20rem; }
/* xwide: 3-column grid for Solutions */
.primary-nav__panel--xwide {
  display: none;
  min-width: 46rem;
}
.primary-nav__panel--xwide[data-open="true"] {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0;
  padding: 0;
}

.primary-nav__section {
  padding: var(--space-3) var(--space-2);
}
.primary-nav__section + .primary-nav__section {
  border-top: 1px solid var(--color-border);
  margin-top: 0;
  padding-top: var(--space-3);
}
/* xwide: sections are columns, separated by vertical rules */
.primary-nav__panel--xwide .primary-nav__section {
  padding: var(--space-4) var(--space-4);
  border-top: none;
}
.primary-nav__panel--xwide .primary-nav__section + .primary-nav__section {
  border-top: none;
  border-left: 1px solid var(--color-border);
  margin-top: 0;
}

.primary-nav__section-label {
  display: block;
  font-size: 0.6875rem;
  font-weight: var(--font-weight-semi);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-fg-quiet);
  padding: 0 var(--space-2) var(--space-2);
  margin-bottom: var(--space-1);
}
.primary-nav__section-grid {
  display: grid;
  gap: 1px;
}
.primary-nav__section-grid a {
  display: flex;
  flex-direction: column;
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius-1);
  color: var(--color-fg-muted);
  text-decoration: none;
  font-size: var(--step--1);
  font-weight: var(--font-weight-medium);
  transition: background var(--duration-fast) var(--ease-standard),
              color var(--duration-fast) var(--ease-standard);
}
.primary-nav__section-grid a strong {
  color: var(--color-fg);
  font-weight: var(--font-weight-semi);
  font-size: var(--step--1);
}
.primary-nav__section-grid a small {
  font-size: 0.6875rem;
  color: var(--color-fg-quiet);
  font-weight: var(--font-weight-normal);
  margin-top: 1px;
}
.primary-nav__section-grid a:hover {
  background: var(--color-bg-alt);
  color: var(--color-fg);
  text-decoration: none;
}

/* Header trailing actions */
.site-header__actions {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  flex-shrink: 0;
}

/* Mobile nav toggle */
.nav-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2.5rem;
  height: 2.5rem;
  background: transparent;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-1);
  color: var(--color-fg);
  cursor: pointer;
}
@media (min-width: 60em) { .nav-toggle { display: none; } }

/* Mobile nav drawer — simple flat list */
.mobile-nav {
  display: none;
  border-top: 1px solid var(--color-border);
  background: var(--color-bg);
  padding: var(--space-5) var(--gutter);
}
.mobile-nav[data-open="true"] { display: block; }
@media (min-width: 60em) { .mobile-nav, .mobile-nav[data-open="true"] { display: none; } }

.mobile-nav__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: var(--space-1);
}
.mobile-nav__list a {
  display: block;
  padding: var(--space-3) var(--space-3);
  border-radius: var(--radius-1);
  color: var(--color-fg-muted);
  text-decoration: none;
  font-weight: var(--font-weight-medium);
  transition: background var(--duration-fast) var(--ease-standard),
              color var(--duration-fast) var(--ease-standard);
}
.mobile-nav__list a:hover { background: var(--color-bg-alt); color: var(--color-fg); }
.mobile-nav__list a[aria-current="page"] { color: var(--color-fg); font-weight: var(--font-weight-semi); }
.mobile-nav__divider {
  height: 1px;
  background: var(--color-border);
  margin-block: var(--space-3);
}
.mobile-nav__cta { margin-top: var(--space-4); }

/* Mobile nav groups — for structured dropdown equivalents */
.mobile-nav__group {
  padding-block: var(--space-3);
  border-bottom: 1px solid var(--color-border);
}
.mobile-nav__group:last-child { border-bottom: none; }
.mobile-nav__group-label {
  display: block;
  font-size: var(--step--1);
  font-weight: var(--font-weight-semi);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-fg-quiet);
  padding: var(--space-2) var(--space-3);
  margin-bottom: var(--space-1);
}
.mobile-nav__sublabel {
  display: block;
  font-size: 0.6875rem;
  font-weight: var(--font-weight-semi);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-fg-quiet);
  padding: var(--space-3) var(--space-3) var(--space-1);
  opacity: 0.65;
}

/* ---- Persona tab strip ------------------------------------------------- */
.persona-tabs {
  position: sticky;
  top: var(--header-height-lg);
  z-index: calc(var(--z-sticky) - 10);
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  height: var(--persona-tab-height);
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
}
.persona-tabs::-webkit-scrollbar { display: none; }

.persona-tabs__inner {
  display: flex;
  align-items: stretch;
  height: 100%;
  padding-inline: var(--gutter);
  gap: 0;
  min-width: max-content;
}
.persona-tabs__link {
  display: inline-flex;
  align-items: center;
  padding-inline: var(--space-4);
  color: var(--color-fg-quiet);
  text-decoration: none;
  font-size: var(--step--1);
  font-weight: var(--font-weight-medium);
  white-space: nowrap;
  border-bottom: 2px solid transparent;
  transition: color var(--duration-fast) var(--ease-standard),
              border-color var(--duration-fast) var(--ease-standard);
}
.persona-tabs__link:hover { color: var(--color-fg); }
.persona-tabs__link[aria-current="page"] {
  color: var(--color-persona-active, var(--color-fg));
  border-bottom-color: var(--color-persona-active, var(--color-accent));
  font-weight: var(--font-weight-semi);
}
/* Hidden on non-persona pages */
.persona-tabs--hidden { display: none; }

@media (min-width: 60em) {
  .persona-tabs { top: var(--header-height-lg); }
}

/* ---- Page-level hero --------------------------------------------------- */
.page-hero {
  padding-block: var(--section-py-large) var(--section-py);
}
.page-hero__eyebrow {
  display: block;
  font-size: var(--step--1);
  font-weight: var(--font-weight-semi);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-persona-active, var(--color-fg-quiet));
  margin-bottom: var(--space-4);
}
.page-hero__title {
  font-size: var(--step-6);
  max-width: 22ch;
  margin-bottom: var(--space-5);
}
.page-hero__lede {
  font-size: var(--step-2);
  color: var(--color-fg-muted);
  max-width: 52ch;
  margin-bottom: var(--space-6);
  line-height: var(--line-height-snug);
}

/* ---- Footer ------------------------------------------------------------ */
.site-footer {
  background: var(--color-bg-dark);
  color: rgba(255,255,255,0.85);
  padding-block: var(--space-9) var(--space-6);
  margin-top: var(--space-10);
}
.site-footer a { color: rgba(255,255,255,0.75); text-decoration: none; }
.site-footer a:hover { color: #fff; text-decoration: underline; }

.site-footer__grid {
  display: grid;
  gap: var(--space-7);
  grid-template-columns: 1fr;
}
@media (min-width: 40em) { .site-footer__grid { grid-template-columns: 1fr 1fr; } }
@media (min-width: 60em) { .site-footer__grid { grid-template-columns: 1.4fr 1fr 1fr 1fr; } }

.site-footer__brand-col p {
  color: rgba(255,255,255,0.55);
  max-width: 32ch;
  margin-top: var(--space-4);
  font-size: var(--step-0);
  line-height: var(--line-height-snug);
}
.site-footer__heading {
  font-size: var(--step--1);
  font-weight: var(--font-weight-semi);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: rgba(255,255,255,0.45);
  margin-bottom: var(--space-4);
}
.site-footer__list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  gap: var(--space-2);
}
.site-footer__bottom {
  margin-top: var(--space-8);
  padding-top: var(--space-5);
  border-top: 1px solid rgba(255,255,255,0.1);
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: var(--space-4);
  color: rgba(255,255,255,0.4);
  font-size: var(--step--1);
}
.site-footer__legal-links {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-4);
  list-style: none;
  margin: 0;
  padding: 0;
}