*,
*::before,
*::after {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
  background: #ece9e1;
}

body {
  min-height: 100vh;
}

.book {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 28px;
  padding: 28px 0;
}

.page {
  position: relative;
  width: var(--page-width);
  height: var(--page-height);
  overflow: hidden;
  background: var(--paper);
  box-shadow: var(--shadow-screen);
}

/*
  Shared page master.

  The four-row grid reserves explicit space for the header and footer.
  minmax(0, 1fr) prevents oversized descendants from forcing the footer
  beyond the physical page.
*/
.page__inner {
  position: absolute;
  inset: 0;
  display: grid;
  grid-template-rows:
    var(--header-height)
    auto
    minmax(0, 1fr)
    var(--footer-height);
  gap: var(--content-gap);
  padding-top: var(--margin-top);
  padding-bottom: var(--margin-bottom);
}

/*
  Mirrored page margins:
  left / verso pages bind on the right;
  right / recto pages bind on the left.
*/
.page--left .page__inner {
  padding-left: var(--margin-outer);
  padding-right: var(--margin-inner);
}

.page--right .page__inner {
  padding-left: var(--margin-inner);
  padding-right: var(--margin-outer);
}

/* Optional neutral master for standalone pages such as proofs or covers. */
.page--single .page__inner {
  padding-left: calc((var(--margin-inner) + var(--margin-outer)) / 2);
  padding-right: calc((var(--margin-inner) + var(--margin-outer)) / 2);
}

.page-header,
.page-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-width: 0;
}

.page-header {
  border-bottom: 0;
}

.page-footer {
  align-self: end;
  gap: var(--space-3);
  min-height: var(--footer-height);
}

.page-footer__rule {
  flex: 1;
  height: 1px;
  background: var(--rule-light);
}

.page-content {
  min-width: 0;
  min-height: 0;
  padding-bottom: var(--footer-clearance);
}

.page-content--two {
  display: grid;
  grid-template-columns: 0.42fr 0.58fr;
  gap: var(--space-5);
}

.page-content--main-sidebar {
  display: grid;
  grid-template-columns: minmax(0, 1fr) var(--sidebar-width);
  gap: var(--space-5);
}

.page-content--field-tool {
  display: grid;
  grid-template-columns: 1.6fr 0.84fr;
  gap: var(--space-5);
  align-items: start;
}

.column {
  min-width: 0;
}

.column + .column {
  border-left: 1px solid var(--rule-light);
  padding-left: var(--space-5);
}

.stack {
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
}

.cluster {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  flex-wrap: wrap;
}

.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: var(--space-3);
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: var(--space-3);
}

.section {
  break-inside: avoid;
  page-break-inside: avoid;
}

.section + .section {
  margin-top: var(--space-5);
}

.field-tool-body {
  margin-top: var(--space-4);
}

.field-tool-intro {
  max-width: 6.7in;
  margin: var(--space-3) auto var(--space-5);
  font-size: var(--fs-md);
}

/*
  Legacy field-tool footer.

  Some existing field-tool pages use an absolutely positioned footer instead
  of the grid-based .page-footer. These rules preserve that structure while
  making its left/right edges follow the mirrored page master.
*/
.field-tool-footer {
  position: absolute;
  bottom: var(--margin-bottom);
  border-top: 1px solid var(--bronze);
  padding-top: var(--space-1);
  text-align: center;
  font-family: var(--font-sans);
  font-size: 7pt;
  font-weight: 700;
  letter-spacing: 0.18em;
  color: var(--olive-dark);
  text-transform: uppercase;
}

.page--left .field-tool-footer {
  left: var(--margin-outer);
  right: var(--margin-inner);
}

.page--right .field-tool-footer {
  left: var(--margin-inner);
  right: var(--margin-outer);
}

.page--single .field-tool-footer {
  left: calc((var(--margin-inner) + var(--margin-outer)) / 2);
  right: calc((var(--margin-inner) + var(--margin-outer)) / 2);
}