/* Book-only header presentation. Header HTML and account behaviour belong
   to consumers; see specimens/book/README.md for the composition contract. */
.mpi-publication .product-header {
  position: relative;
  z-index: 1031;
  min-height: 0;
  background: var(--product-surface);
  border-bottom: 1px solid var(--product-border);
  color: var(--product-ink);
  font-family: "Source Sans 3", ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

.mpi-publication .product-header__nav {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.25rem;
  max-width: 1440px;
  min-height: 56px;
  padding: 0 1rem;
  margin: 0 auto;
}

.mpi-publication .product-header a,
.mpi-publication .product-header summary {
  box-sizing: border-box;
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding: 0.5rem 0.75rem;
  color: var(--product-ink);
  font-size: 0.9375rem;
  font-weight: 600;
  line-height: 1.25;
  text-decoration: none;
  overflow-wrap: anywhere;
}

.mpi-publication .product-header a:hover {
  color: var(--product-primary-hover);
}

.mpi-publication .product-header a:focus-visible,
.mpi-publication .product-header summary:focus-visible {
  outline: 3px solid var(--product-focus);
  outline-offset: -3px;
}

.mpi-publication .product-header__brand {
  gap: 0.55rem;
  padding-left: 0;
}

.mpi-publication .product-header__mark {
  display: block;
  flex: 0 0 auto;
  height: 32px;
  width: 32px;
}

.mpi-publication .product-header__title {
  color: var(--product-ink);
  font-weight: 700;
  white-space: nowrap;
}

.mpi-publication .product-header__desktop-links {
  display: flex;
  align-items: center;
  gap: 0.25rem;
}

.mpi-publication .product-header__link--active {
  border-bottom: 3px solid var(--product-primary);
}

.mpi-publication .product-header__account-actions {
  display: flex;
  align-items: center;
  gap: 0.25rem;
  margin-left: auto;
}

.mpi-publication .product-header__primary-action {
  background: var(--product-primary);
  color: var(--product-surface) !important;
}

.mpi-publication .product-header__primary-action:hover {
  background: var(--product-primary-hover);
}

.mpi-publication .product-header__mobile-menu {
  display: none;
  position: relative;
  margin-left: auto;
}

.mpi-publication .product-header__mobile-menu > summary {
  justify-content: center;
  width: 44px;
  cursor: pointer;
  list-style: none;
}

.mpi-publication .product-header__mobile-menu > summary::-webkit-details-marker {
  display: none;
}

.mpi-publication .product-header__mobile-links {
  position: absolute;
  top: calc(100% + 0.25rem);
  right: 0;
  display: grid;
  min-width: 12rem;
  padding: 0.25rem;
  background: var(--product-surface);
  border: 1px solid var(--product-border);
}

.mpi-publication .product-header__mobile-links a {
  width: 100%;
}

/* Producer contract: place the product row inside #quarto-header.fixed-top.
   Keep the measured stack in flow before deferred Quarto initialization.
   Its observer still supplies sidebar/anchor offsets; body padding must not
   reserve the same height twice. No independent fixed-height guess. */
.mpi-publication #quarto-header {
  position: sticky;
  top: 0;
  background: var(--mpi-surface);
}

body.mpi-publication {
  padding-top: 0 !important;
}

.mpi-publication .product-header__desktop-links > a,
.mpi-publication .product-header__account-actions > a {
  white-space: nowrap;
}

.mpi-publication .product-header__account-actions {
  min-inline-size: 0;
}

.mpi-publication .product-header .account-menu {
  position: relative;
  min-inline-size: 0;
}

.mpi-publication .product-header .account-menu summary {
  cursor: pointer;
  max-inline-size: 24rem;
}

.mpi-publication .product-header .account-menu__panel,
.mpi-publication .product-header__mobile-links {
  max-inline-size: calc(100vw - 2rem);
  max-block-size: 65vh;
  overflow-y: auto;
  overscroll-behavior: contain;
}

.mpi-publication .product-header .account-menu__panel {
  position: absolute;
  inset-inline-end: 0;
  background: var(--product-surface);
  border: 1px solid var(--product-border);
  display: grid;
  min-inline-size: min(12rem, calc(100vw - 2rem));
  padding: 0.25rem;
  z-index: 1032;
}

.mpi-publication .product-header .account-menu__panel form {
  margin: 0;
}

.mpi-publication .product-header .account-menu__panel :is(a, button) {
  background: transparent;
  border: 0;
  color: var(--product-ink);
  display: flex;
  align-items: center;
  font: inherit;
  min-block-size: 44px;
  padding: 0.5rem 0.75rem;
  inline-size: 100%;
  text-align: start;
}

.mpi-publication .product-header button:focus-visible {
  outline: 3px solid var(--product-focus);
  outline-offset: -3px;
}

.mpi-publication .product-header__mobile-links .account-menu__panel {
  position: static;
  min-inline-size: 0;
  max-inline-size: 100%;
}

/* With scripting disabled there is no Quarto measurement. Keep both header
   rows in normal flow so reading and native disclosures remain unobscured. */
@media (scripting: none) {
  .mpi-publication #quarto-header {
    position: static !important;
  }
}

@media (max-width: 991.98px) {
  .mpi-publication .product-header__title,
  .mpi-publication .product-header__desktop-links,
  .mpi-publication .product-header__account-actions {
    display: none;
  }

  .mpi-publication .product-header__mobile-menu {
    display: block;
  }
}

@media (prefers-reduced-motion: reduce) {
  .mpi-publication .product-header,
  body.mpi-lms-integrated #quarto-header {
    transition: none !important;
  }
}