/* DECODE — layout
   Grid, container, panel primitives, rule headers, site chrome. */

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

.grid {
  display: grid;
  grid-template-columns: repeat(var(--columns), minmax(0, 1fr));
  column-gap: var(--gutter);
  row-gap: var(--space-6);
}

.col-2 { grid-column: span 2; }
.col-3 { grid-column: span 3; }
.col-4 { grid-column: span 4; }
.col-5 { grid-column: span 5; }
.col-6 { grid-column: span 6; }
.col-7 { grid-column: span 7; }
.col-8 { grid-column: span 8; }
.col-9 { grid-column: span 9; }
.col-10 { grid-column: span 10; }
.col-12 { grid-column: span 12; }

@media (max-width: 960px) {
  .col-2, .col-3, .col-4, .col-5, .col-6, .col-7, .col-8, .col-9, .col-10 {
    grid-column: span 12;
  }
}

/* ---------- Vertical rhythm ---------- */
.section {
  padding-block: var(--space-8);
}

.section--tight {
  padding-block: var(--space-6);
}

.stack > * + * {
  margin-top: var(--space-4);
}

.stack--tight > * + * {
  margin-top: var(--space-2);
}

.stack--loose > * + * {
  margin-top: var(--space-6);
}

.measure {
  max-width: var(--measure);
}

/* ---------- Panels ---------- */
.panel {
  background: var(--panel-1);
  border: 1px solid var(--hairline);
  border-radius: var(--radius-panel);
}

.panel--raised {
  background: var(--panel-1);
  border-color: var(--hairline-strong);
}

.panel--flat {
  background: transparent;
  border: 0;
  border-top: 1px solid var(--hairline);
  border-radius: 0;
}

.panel__body {
  padding: var(--space-5);
}

.panel__body--tight {
  padding: var(--space-4);
}

/* Hairlines separate, never boxes-in-boxes: a panel divides itself with rules. */
.panel__row {
  padding: var(--space-4) var(--space-5);
}

.panel__row + .panel__row {
  border-top: 1px solid var(--hairline);
}

/* ---------- Rule headers: the title sits on the hairline ---------- */
.rule {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  min-width: 0;
}

.rule::after {
  content: "";
  flex: 1 1 auto;
  height: 0;
  border-top: 1px solid var(--hairline);
}

.rule__title {
  flex: 0 0 auto;
  font-size: var(--step-0);
  font-weight: 500;
  color: var(--ink-2);
  letter-spacing: 0;
  line-height: var(--leading-flat);
}

.rule__meta {
  order: 3;
  flex: 0 0 auto;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: var(--step--1);
  color: var(--ink-3);
}

.rule--strong .rule__title {
  color: var(--ink);
  font-size: var(--step-2);
}

/* ---------- Chapter opener / one-idea statement ---------- */
.idea {
  font-family: var(--font-serif);
  font-style: italic;
  font-weight: 400;
  font-size: var(--step-4);
  line-height: 1.25;
  letter-spacing: 0;
  color: var(--ink);
  max-width: 30ch;
  text-wrap: balance;
}

/* ---------- Site header ---------- */
[data-site-header] {
  min-height: var(--header-height);
}

[data-site-footer] {
  min-height: 120px;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  height: var(--header-height);
  background: color-mix(in srgb, var(--panel-0) 92%, transparent);
  -webkit-backdrop-filter: blur(12px);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--hairline);
}

.site-header__inner {
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-5);
}

.wordmark {
  font-family: var(--font-sans);
  font-weight: 600;
  font-size: var(--step-2);
  letter-spacing: var(--tracking-tight);
  color: var(--ink);
  text-decoration: none;
  display: inline-flex;
  align-items: baseline;
  gap: var(--space-2);
  white-space: nowrap;
}

.wordmark__mark {
  display: inline-block;
  width: 10px;
  height: 10px;
  align-self: center;
  border: 1.5px solid currentColor;
  border-radius: 1px;
  position: relative;
}

.wordmark__mark::after {
  content: "";
  position: absolute;
  right: -1.5px;
  top: 2px;
  bottom: 2px;
  width: 3px;
  background: var(--panel-0);
}

.nav {
  display: flex;
  align-items: center;
  gap: var(--space-5);
}

.nav__list {
  display: flex;
  align-items: center;
  gap: var(--space-5);
  list-style: none;
  padding: 0;
  margin: 0;
}

.nav__link {
  font-size: var(--step-0);
  font-weight: 500;
  color: var(--ink-2);
  text-decoration: none;
  padding-block: var(--space-1);
  border-bottom: 1px solid transparent;
  transition: color var(--dur-micro) var(--ease-out), border-color var(--dur-micro) var(--ease-out);
}

.nav__link:hover {
  color: var(--ink);
}

.nav__link[aria-current="page"],
.nav__link[aria-current="true"] {
  color: var(--ink);
  border-bottom-color: var(--ink);
}

.nav-toggle {
  display: none;
}

@media (max-width: 720px) {
  .nav-toggle {
    display: inline-flex;
    align-items: center;
    gap: var(--space-2);
    height: 36px;
    padding: 0 var(--space-3);
    background: transparent;
    border: 1px solid var(--hairline-strong);
    border-radius: var(--radius-input);
    color: var(--ink);
    font-size: var(--step-0);
    font-weight: 500;
  }

  .nav-toggle__bars {
    display: inline-block;
    width: 14px;
    height: 10px;
    border-top: 1.5px solid currentColor;
    border-bottom: 1.5px solid currentColor;
    position: relative;
  }

  .nav-toggle__bars::after {
    content: "";
    position: absolute;
    left: 0;
    right: 0;
    top: 50%;
    border-top: 1.5px solid currentColor;
    transform: translateY(-50%);
  }

  .nav {
    position: fixed;
    inset: var(--header-height) 0 0 0;
    background: var(--panel-0);
    border-top: 1px solid var(--hairline);
    padding: var(--space-6) var(--margin);
    display: none;
    overflow-y: auto;
  }

  .nav[data-open="true"] {
    display: block;
  }

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

  .nav__list li + li {
    border-top: 1px solid var(--hairline);
  }

  .nav__link {
    display: block;
    font-size: var(--step-3);
    font-weight: 500;
    padding-block: var(--space-4);
    border-bottom: 0;
  }

  .nav__link[aria-current="page"],
  .nav__link[aria-current="true"] {
    border-bottom: 0;
    padding-left: var(--space-3);
    box-shadow: inset 2px 0 0 var(--ink);
  }
}

/* ---------- Page header block ---------- */
.page-head {
  padding-block: var(--space-7) var(--space-6);
  border-bottom: 1px solid var(--hairline);
}

.page-head__title {
  font-size: var(--step-5);
  font-weight: 600;
  letter-spacing: var(--tracking-display);
}

.page-head__lede {
  margin-top: var(--space-4);
  color: var(--ink-2);
  font-size: var(--step-2);
  line-height: 1.4;
  max-width: 52ch;
}

@media (max-width: 720px) {
  .page-head {
    padding-block: var(--space-6) var(--space-5);
  }

  .page-head__title {
    font-size: var(--step-4);
  }

  .page-head__lede {
    font-size: var(--step-1);
  }
}

/* ---------- Site footer ---------- */
.site-footer {
  margin-top: var(--space-9);
  border-top: 1px solid var(--hairline);
  padding-block: var(--space-6);
  color: var(--ink-2);
  font-size: var(--step-0);
}

.site-footer__inner {
  display: grid;
  grid-template-columns: 1fr auto auto;
  gap: var(--space-5);
  align-items: baseline;
}

.site-footer a {
  color: var(--ink-2);
}

.site-footer a:hover {
  color: var(--ink);
}

.site-footer__stamp {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: var(--step--1);
  color: var(--ink-3);
}

@media (max-width: 720px) {
  .site-footer__inner {
    grid-template-columns: 1fr;
    gap: var(--space-3);
  }
}