/* ─────────────────────────────────────────────────────────────────────────────
   layout.css — masthead, footer, page sections
   ───────────────────────────────────────────────────────────────────────────── */

/* MASTHEAD ─────────────────────────────────────────────────────────── */
.masthead {
  /* Slightly translucent so the backdrop-filter actually frosts content
     scrolling underneath (a fully opaque bg made the blur a no-op). */
  background: color-mix(in srgb, var(--c-paper) 85%, transparent);
  position: sticky;
  top: 0;
  z-index: 30;
  backdrop-filter: saturate(140%) blur(8px);
  -webkit-backdrop-filter: saturate(140%) blur(8px);
}
@supports not (backdrop-filter: blur(1px)) {
  .masthead { background: var(--c-paper); }  /* opaque fallback, no see-through */
}
.masthead__inner {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: var(--sp-5);
  padding-block: var(--sp-4);
}
.masthead__rule {
  height: 1px;
  background: linear-gradient(
    to right,
    transparent 0%,
    var(--c-line) 18%,
    var(--c-line-strong) 50%,
    var(--c-line) 82%,
    transparent 100%
  );
}

/* Brand: monogram + name + sub */
.brand {
  display: inline-flex;
  align-items: center;
  gap: var(--sp-3);
  text-decoration: none;
  color: var(--c-ink);
}
.brand:hover { color: var(--c-brand); }
.brand__mark {
  display: inline-flex;
  width: 36px; height: 36px;
  align-items: center; justify-content: center;
  border: 1px solid var(--c-line-strong);
  border-radius: 999px;
  color: var(--c-brand);
  background: var(--c-paper);
  transition: transform var(--dur-base) var(--ease-emph);
}
.brand:hover .brand__mark { transform: rotate(-8deg); }
.brand__text { display: flex; flex-direction: column; line-height: 1.05; }
.brand__name {
  font-family: var(--ff-serif);
  font-weight: 600;
  font-size: 1.15rem;
  letter-spacing: var(--tracking-tight);
}
.brand__sub {
  font-size: var(--fs-xs);
  color: var(--c-ink-mute);
  letter-spacing: var(--tracking-caps);
  text-transform: uppercase;
  margin-top: 0.25em;
}

/* Primary nav */
.primary-nav {
  display: flex;
  justify-content: center;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--sp-2) var(--sp-5);
  min-width: 0;
  overflow: visible;
  position: relative;
}
.nav-item {
  position: relative;
  flex: 0 0 auto;
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  text-decoration: none;
  color: var(--c-ink-soft);
  padding: var(--sp-2) 0;
  font-weight: 500;
  font-family: inherit;
  font-size: inherit;
  white-space: nowrap;
  letter-spacing: 0;
  transition: color var(--dur-fast) var(--ease-standard);
}
.nav-item::after {
  content: "";
  position: absolute;
  left: 0; right: 0; bottom: 0;
  height: 1px;
  background: var(--c-brand);
  transform: scaleX(0);
  transform-origin: center;
  transition: transform var(--dur-base) var(--ease-emph);
}
.nav-item:hover { color: var(--c-ink); }
.nav-item:hover::after { transform: scaleX(0.5); }
.nav-item.is-active {
  color: var(--c-brand);
}
.nav-item.is-active::after { transform: scaleX(1); }

.nav-menu {
  position: relative;
  flex: 0 0 auto;
}
.nav-menu > summary {
  list-style: none;
  cursor: pointer;
  user-select: none;
}
.nav-menu > summary::-webkit-details-marker { display: none; }
.nav-menu__trigger {
  gap: var(--sp-2);
  border: 0;
  background: transparent;
}
.nav-menu__chevron {
  width: 7px;
  height: 7px;
  border-right: 1.5px solid currentColor;
  border-bottom: 1.5px solid currentColor;
  transform: rotate(45deg) translateY(-2px);
  transition: transform var(--dur-fast) var(--ease-standard);
}
.nav-menu[open] .nav-menu__chevron {
  transform: rotate(225deg) translate(-1px, -1px);
}
.nav-menu.is-active > .nav-menu__trigger,
.nav-menu[open] > .nav-menu__trigger {
  color: var(--c-brand);
}
.nav-menu.is-active > .nav-menu__trigger::after { transform: scaleX(1); }
.nav-menu__panel {
  position: absolute;
  top: calc(100% + var(--sp-2));
  left: calc(var(--sp-3) * -1);
  z-index: 60;
  display: grid;
  min-width: 190px;
  padding: var(--sp-2);
  background: var(--c-paper);
  border: 1px solid var(--c-line-strong);
  border-radius: var(--r-md);
  box-shadow: 0 14px 32px color-mix(in srgb, var(--c-ink) 14%, transparent);
}
.nav-menu--end .nav-menu__panel {
  right: calc(var(--sp-3) * -1);
  left: auto;
}
.nav-menu__item {
  display: flex;
  align-items: center;
  min-height: 44px;
  padding: var(--sp-2) var(--sp-3);
  border-radius: var(--r-sm);
  color: var(--c-ink-soft);
  text-decoration: none;
  white-space: nowrap;
}
.nav-menu__item:hover,
.nav-menu__item:focus-visible {
  color: var(--c-ink);
  background: var(--c-paper-soft);
}
.nav-menu__item.is-active {
  color: var(--c-brand);
  background: var(--c-brand-glow);
  font-weight: 600;
}

/* User menu */
.user-menu {
  display: flex; align-items: center; gap: var(--sp-3);
  justify-self: end;
}
.logout-form { display: inline; }
.user-chip {
  display: inline-flex; align-items: center; gap: var(--sp-2);
  text-decoration: none;
  color: var(--c-ink);
  font-weight: 500;
}
.user-chip:hover { color: var(--c-brand); }
.user-chip__name { font-size: var(--fs-small); }
.avatar {
  width: 30px; height: 30px;
  border-radius: 50%;
  background: var(--c-brand);
  color: var(--c-paper);
  display: inline-flex; align-items: center; justify-content: center;
  font-weight: 600; font-size: 0.85rem;
  font-family: var(--ff-serif);
}

/* FOOTER ──────────────────────────────────────────────────────────── */
.page__footer {
  border-top: 1px solid var(--c-paper-edge);
  background: var(--c-paper);
  padding-block: var(--sp-6);
  margin-top: var(--sp-8);
}
.footer__inner {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--sp-4);
  flex-wrap: wrap;
}
.footer__line {
  margin: 0;
  font-size: var(--fs-small);
  color: var(--c-ink-mute);
}
.footer__sep { padding-inline: 0.6em; color: var(--c-ink-faint); }
.footer__id {
  margin: 0;
  font-family: var(--ff-mono);
  font-size: var(--fs-xs);
  color: var(--c-ink-faint);
  letter-spacing: 0.04em;
}

/* SECTIONS ────────────────────────────────────────────────────────── */
.section { padding-block: var(--sp-6); }
.section--hero { padding-block: var(--sp-8) var(--sp-6); }
.section__head {
  display: flex; align-items: baseline; justify-content: space-between;
  gap: var(--sp-4); flex-wrap: wrap;
  margin-bottom: var(--sp-5);
}
.section__title {
  font-size: var(--fs-3);
  font-weight: 600;
}
.section__hint { font-size: var(--fs-small); color: var(--c-ink-mute); }
.section__more {
  font-size: var(--fs-small);
  color: var(--c-ink-soft);
}

/* Two-column reading layout: aside 240px sticky, main 1fr */
.layout-with-aside {
  display: grid;
  grid-template-columns: 240px minmax(0, 1fr);
  gap: var(--sp-7);
  align-items: start;
}
.layout-with-aside > * { min-width: 0; }
@media (max-width: 880px) {
  .layout-with-aside { grid-template-columns: 1fr; }
  .layout-with-aside > .aside { display: none; }
}

.aside {
  position: sticky;
  top: calc(var(--sp-8) + var(--sp-4));
  max-height: calc(100vh - var(--sp-8) - var(--sp-4) - var(--sp-4));
  overflow-y: auto;
  overscroll-behavior: contain;
  font-size: var(--fs-small);
}
.aside__title {
  font-size: var(--fs-xs);
  text-transform: uppercase;
  letter-spacing: var(--tracking-caps);
  color: var(--c-ink-mute);
  margin: 0 0 var(--sp-3);
}
.aside__list { list-style: none; padding: 0; margin: 0; line-height: 1.6; }
.aside__list a {
  text-decoration: none;
  color: var(--c-ink-soft);
  display: block;
  padding: 0.2em 0;
}
.aside__list a:hover { color: var(--c-brand); }
.aside__list .lvl-3 { padding-left: 1em; color: var(--c-ink-mute); }
.aside__list .lvl-4 { padding-left: 2em; color: var(--c-ink-faint); }
/* Scrollspy: highlight the TOC entry for the section currently in view. */
.aside__list li.is-current > a {
  color: var(--c-brand);
  font-weight: 600;
  border-left: 2px solid var(--c-brand);
  padding-left: 0.5em;
  margin-left: -0.5em;
}

/* Compact masthead: keep navigation readable without a long horizontal strip. */
@media (max-width: 1180px) {
  .masthead__inner { grid-template-columns: 1fr auto; }
  .primary-nav {
    grid-column: 1 / -1;
    grid-row: 2;
    justify-content: flex-start;
    padding-bottom: var(--sp-2);
    gap: var(--sp-1) var(--sp-4);
  }
}
@media (max-width: 720px) {
  .masthead__inner { column-gap: var(--sp-3); row-gap: var(--sp-2); }
  .brand__sub { display: none; }
  .user-menu { gap: var(--sp-2); }
  .user-chip__name { display: none; }
  .primary-nav { gap: 0 var(--sp-4); }
  .nav-menu { position: static; }
  .nav-menu__panel,
  .nav-menu--end .nav-menu__panel {
    top: calc(100% + var(--sp-2));
    right: 0;
    left: 0;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    min-width: 0;
  }
  .nav-menu__item { white-space: normal; }
}