/* ==========================================================================
   LAYOUT - page shell, containers, primitives, header, navigation, footer.
   ========================================================================== */

/* ------------------------------------------------------------- page shell */
.page {
  display: flex;
  flex-direction: column;
  min-height: 100svh;
}

.page__main { flex: 1 0 auto; }

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

.container--narrow { max-width: var(--container-narrow); }
.container--wide { max-width: var(--container-wide); }

/* --------------------------------------------------------------- sections */
.section { padding-block: var(--section-y); }
.section--tight { padding-block: var(--space-xl); }
.section--flush-top { padding-block-start: 0; }
.section--flush-bottom { padding-block-end: 0; }

.section--alt { background-color: var(--bg-alt); }

.section--sunk {
  background-color: var(--paper-2);
  color: var(--text);
  position: relative;
  isolation: isolate;
}

.section--sunk::after {
  content: "";
  position: absolute;
  inset: 0;
  background-image: var(--grain);
  opacity: 0.22;
  mix-blend-mode: overlay;
  pointer-events: none;
  z-index: -1;
}

.section--sunk :is(h1, h2, h3, h4) { color: var(--white); }

/* Section header: eyebrow + title + lede, used on every page. */
.section__head {
  display: flex;
  flex-direction: column;
  gap: var(--space-xs);
  max-width: 44rem;
  margin-block-end: var(--space-l);
}

.section__head--centred {
  margin-inline: auto;
  text-align: center;
  align-items: center;
}

.section__head--split {
  max-width: none;
  flex-direction: row;
  align-items: flex-end;
  justify-content: space-between;
  gap: var(--space-m);
  flex-wrap: wrap;
}

.section__head--split > :first-child { max-width: 44rem; }

.section__lede {
  font-size: var(--step-1);
  color: var(--text-muted);
  line-height: 1.5;
}

/* ------------------------------------------------------------- primitives
   Small, composable layout helpers. Reach for these before writing a new
   bespoke grid. */
.stack {
  display: flex;
  flex-direction: column;
  gap: var(--stack-gap, var(--space-s));
}

.stack > * { margin-block: 0; }

.cluster {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--cluster-gap, var(--space-s));
}

.grid {
  display: grid;
  gap: var(--grid-gap, var(--space-m));
  grid-template-columns: repeat(var(--grid-cols, 1), minmax(0, 1fr));
}

/* Auto-fitting grid - no breakpoints needed, items wrap on their own. */
.grid--auto {
  grid-template-columns: repeat(auto-fit, minmax(min(var(--grid-min, 17rem), 100%), 1fr));
}

@media (min-width: 40em) {
  .grid--2 { --grid-cols: 2; }
  .grid--3 { --grid-cols: 2; }
  .grid--4 { --grid-cols: 2; }
}

@media (min-width: 62em) {
  .grid--3 { --grid-cols: 3; }
  .grid--4 { --grid-cols: 4; }
}

/* Two-column split that collapses to one on small screens. */
.split {
  display: grid;
  gap: var(--space-l);
  align-items: var(--split-align, center);
}

@media (min-width: 56em) {
  .split { grid-template-columns: var(--split-cols, 1fr 1fr); gap: var(--space-xl); }
  .split--reverse > :first-child { order: 2; }
}

/* ==========================================================================
   SKIP LINK
   ========================================================================== */
.skip-link {
  position: fixed;
  inset-block-start: var(--space-2xs);
  inset-inline-start: var(--space-2xs);
  z-index: var(--z-overlay);
  padding: var(--space-2xs) var(--space-s);
  background-color: var(--brand);
  color: var(--on-brand);
  border-radius: 0;
  font-weight: 700;
  text-decoration: none;
  transform: translateY(-200%);
  transition: transform var(--dur) var(--ease-out);
}

.skip-link:focus-visible {
  transform: translateY(0);
  color: var(--on-brand);
}

/* ==========================================================================
   SITE HEADER
   ========================================================================== */
.site-header {
  position: sticky;
  inset-block-start: 0;
  z-index: var(--z-header);
  isolation: isolate;
  border-block-end: 0;
  transition: border-color var(--dur) var(--ease-out),
              box-shadow var(--dur) var(--ease-out);
}

/* The frosted bar lives on a pseudo-element, not on .site-header itself.
   backdrop-filter turns an element into the containing block for its
   position:fixed descendants, which would trap the mobile menu panel inside
   the header bar instead of letting it fill the viewport. */
.site-header::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  background-color: color-mix(in srgb, var(--bg) 82%, transparent);
  backdrop-filter: blur(14px) saturate(140%);
  -webkit-backdrop-filter: blur(14px) saturate(140%);
  transition: background-color var(--dur) var(--ease-out);
}

/* Set by JS once the page is scrolled past the hero threshold. */
.site-header.is-stuck {
  border-block-end-color: transparent;
  box-shadow: none;
}

.site-header.is-stuck::before {
  background-color: color-mix(in srgb, var(--bg) 94%, transparent);
}

.site-header__inner {
  position: relative;
  z-index: 2; /* keeps the logo and the close button above the open panel */
  display: flex;
  align-items: center;
  gap: var(--space-m);
  min-height: var(--header-h);
}

/* ------------------------------------------------------------------ brand */
.brand {
  display: inline-flex;
  align-items: center;
  flex: none;
  white-space: nowrap; /* a wordmark must never wrap */
  gap: 0.6rem;
  color: var(--text);
  text-decoration: none;
  font-family: var(--font-display);
  font-size: var(--step-1);
  font-weight: 600;
  letter-spacing: var(--tracking-tight);
  line-height: 1;
  margin-inline-end: auto;
}

.brand__mark {
  width: 2rem;
  height: 2rem;
  flex: none;
  border-radius: 0;
  transition: transform var(--dur) var(--ease-spring);
}

.brand__logo {
  width: 5rem;
  height: auto;
  flex: none;
  border-radius: 0;
  transition: transform var(--dur) var(--ease-spring);
}

.brand:hover .brand__mark { transform: rotate(-8deg) scale(1.06); }

/* The inline logo takes its colours from the brand tokens, so re-branding
   the site re-colours the mark too - no image to re-export. */
.brand__mark-bg { fill: var(--brand); }
.brand__mark-fg { fill: var(--white); }

.brand__name-accent { color: var(--brand); font-style: italic; }

/* ==========================================================================
   PRIMARY NAV - inline bar on desktop, off-canvas panel on mobile.
   ========================================================================== */
.primary-nav__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  align-items: center;
  gap: clamp(var(--space-xs), 1.4vw, var(--space-m));
}

.primary-nav__link {
  --underline: 0;
  position: relative;
  display: inline-block;
  padding-block: var(--space-2xs);
  color: var(--text);
  text-decoration: none;
  font-size: var(--step--1);
  font-weight: 500;
  letter-spacing: 0.01em;
}

.primary-nav__link::after {
  content: "";
  position: absolute;
  inset-block-end: 0;
  inset-inline-start: 0;
  width: 100%;
  height: 2px;
  background-color: var(--brand);
  border-radius: var(--radius-pill);
  transform: scaleX(var(--underline));
  transform-origin: left;
  transition: transform var(--dur) var(--ease-out);
}

.primary-nav__link:hover,
.primary-nav__link:focus-visible { color: var(--brand); }

.primary-nav__link:hover { --underline: 1; }

/* Current page is marked in the HTML with aria-current="page" - the style
   follows the semantics rather than a duplicated .is-active class. */
.primary-nav__link[aria-current="page"] {
  --underline: 1;
  color: var(--brand);
  font-weight: 700;
}

.primary-nav__aside { display: none; }

/* --------------------------------------------------------- burger button */
.nav-toggle {
  display: none;
  position: relative;
  width: 2.75rem;
  height: 2.75rem;
  flex: none;
  border-radius: 0;
  color: var(--text);
}

.nav-toggle__box {
  position: absolute;
  inset: 0;
  display: grid;
  place-content: center;
  gap: 5px;
}

.nav-toggle__bar {
  display: block;
  width: 22px;
  height: 2px;
  background-color: currentColor;
  border-radius: 0;
  transition: transform var(--dur) var(--ease-out),
              opacity var(--dur-fast) linear;
}

.site-header.is-nav-open .nav-toggle__bar:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.site-header.is-nav-open .nav-toggle__bar:nth-child(2) { opacity: 0; transform: scaleX(0.2); }
.site-header.is-nav-open .nav-toggle__bar:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ------------------------------------------------------------- backdrop */
.nav-backdrop {
  position: fixed;
  inset: 0;
  z-index: var(--z-backdrop);
  background-color: rgba(0, 0, 0, 0.32);
  backdrop-filter: none;
  opacity: 0;
  visibility: hidden;
  transition: opacity var(--dur) var(--ease-out), visibility var(--dur);
}

/* ==========================================================================
   MOBILE NAVIGATION
   Everything above 60em is the desktop bar; below it the same markup becomes
   a slide-in panel. One breakpoint, one source of truth.
   ========================================================================== */
@media (max-width: 59.99em) {
  /* The panel is a child of .site-header__inner, so the logo and the close
     button need to out-rank it inside that stacking context. */
  .nav-toggle { display: block; z-index: 2; }

  .brand { position: relative; z-index: 2; }

  .site-header .site-header__cta { display: none; }

  .primary-nav {
    position: fixed;
    inset-block: 0;
    inset-inline-end: 0;
    z-index: 1; /* inside the header's stacking context, below .site-header__inner */
    width: min(22rem, 86vw);
    padding: calc(var(--header-h) + var(--space-m)) var(--space-l) var(--space-l);
    background-color: var(--surface);
    border-inline-start: 0;
    box-shadow: none;
    display: flex;
    flex-direction: column;
    gap: var(--space-l);
    overflow-y: auto;
    overscroll-behavior: contain;
    transform: translateX(100%);
    visibility: hidden;
    transition: transform var(--dur-slow) var(--ease-out), visibility var(--dur-slow);
  }

  .primary-nav__list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
  }

  .primary-nav__list > li + li { border-block-start: var(--border-width) solid var(--border); }

  .primary-nav__link {
    display: block;
    padding-block: var(--space-s);
    font-family: var(--font-display);
    font-size: var(--step-2);
    font-weight: 600;
    letter-spacing: var(--tracking-tight);
  }

  .primary-nav__link::after { display: none; }

  .primary-nav__link[aria-current="page"]::before {
    content: "";
    display: inline-block;
    width: 0.45em;
    height: 0.45em;
    margin-inline-end: 0.5em;
    border-radius: 50%;
    background-color: var(--brand);
    vertical-align: middle;
  }

  .primary-nav__aside {
    display: flex;
    flex-direction: column;
    gap: var(--space-s);
    margin-block-start: auto;
    padding-block-start: var(--space-m);
    border-block-start: var(--border-width) solid var(--border);
  }

  /* --- open state --- */
  .site-header.is-nav-open .primary-nav {
    transform: translateX(0);
    visibility: visible;
  }

  .site-header.is-nav-open ~ .nav-backdrop,
  .site-header.is-nav-open + .nav-backdrop {
    opacity: 1;
    visibility: visible;
  }

  /* Staggered reveal of the links once the panel is open. */
  .site-header.is-nav-open .primary-nav__list > li {
    animation: nav-item-in var(--dur-slow) var(--ease-out) backwards;
    animation-delay: calc(120ms + var(--i, 0) * 55ms);
  }
}

@keyframes nav-item-in {
  from { opacity: 0; transform: translateX(1.5rem); }
  to { opacity: 1; transform: translateX(0); }
}

/* ==========================================================================
   SITE FOOTER
   ========================================================================== */
.site-footer {
  position: relative;
  isolation: isolate;
  background-color: var(--bg-alt);
  color: var(--text);
  padding-block: var(--space-2xl) var(--space-l);
  margin-block-start: auto;
}

.site-footer::after {
  content: "";
  position: absolute;
  inset: 0;
  background-image: var(--grain);
  opacity: 0.3;
  pointer-events: none;
  z-index: -1;
}

.site-footer a { color: var(--text-muted); text-decoration: none; }
.site-footer a:hover { color: var(--white); text-decoration: underline; }

.site-footer__grid {
  display: grid;
  gap: var(--space-l);
  grid-template-columns: repeat(auto-fit, minmax(min(14rem, 100%), 1fr));
}

.site-footer__brand { grid-column: 1 / -1; }

@media (min-width: 62em) {
  .site-footer__grid { grid-template-columns: 1.6fr repeat(3, 1fr); }
  .site-footer__brand { grid-column: auto; }
}

.site-footer .brand { color: var(--white); margin-inline-end: 0; }

.site-footer__tagline {
  margin-block-start: var(--space-s);
  max-width: 30ch;
  color: var(--text-muted);
}

.site-footer__title {
  font-family: var(--font-body);
  font-size: var(--step--2);
  font-weight: 700;
  letter-spacing: var(--tracking-label);
  text-transform: uppercase;
  color: var(--text-subtle);
  margin-block-end: var(--space-s);
}

.site-footer__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: var(--space-2xs);
  font-size: var(--step--1);
}

.site-footer__bottom {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-s);
  margin-block-start: var(--space-xl);
  padding-block-start: var(--space-m);
  border-block-start: var(--border-width) solid var(--border);
  font-size: var(--step--2);
  color: var(--text-subtle);
}

.site-footer__legal {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-s);
  list-style: none;
  margin: 0;
  padding: 0;
}