/* Concept Base - single stylesheet. No external resources, no web fonts. */

:root {
  --bg: #f4f1ea;
  --surface: #ffffff;
  --surface-alt: #ece7db;
  --ink: #1b2422;
  --muted: #4c5a57;
  --accent: #0b5d63;
  --accent-dark: #074246;
  --olive: #4a5d23;
  --line: #d5cfc2;
  --line-strong: #b9b1a0;
  --radius: 3px;
  --measure: 68ch;
  --step: 1.25rem;
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --mono: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font);
  font-size: 1.0625rem;
  line-height: 1.68;
  overflow-wrap: break-word;
}

.wrap {
  width: 100%;
  max-width: 62rem;
  margin: 0 auto;
  padding: 0 1.25rem;
}

main { display: block; }

.skip {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--accent-dark);
  color: #fff;
  padding: 0.65rem 1rem;
  z-index: 50;
}
.skip:focus { left: 0; }

a { color: var(--accent-dark); }
a:hover { color: var(--accent); }

:focus-visible {
  outline: 3px solid var(--olive);
  outline-offset: 2px;
}

/* ---------- header ---------- */

.site-head {
  position: sticky;
  top: 0;
  z-index: 40;
  background: var(--surface);
  border-bottom: 1px solid var(--line-strong);
}

.head-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.7rem 0;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  font-weight: 700;
  letter-spacing: 0.01em;
  text-decoration: none;
  color: var(--ink);
  font-size: 1.05rem;
}

.brand-mark {
  display: inline-grid;
  place-items: center;
  width: 2rem;
  height: 2rem;
  border-radius: var(--radius);
  background: var(--accent);
  color: #fff;
  font-size: 0.8rem;
  letter-spacing: 0.04em;
}

.nav-toggle {
  display: none;
  font: inherit;
  font-size: 0.95rem;
  background: var(--surface);
  color: var(--ink);
  border: 1px solid var(--line-strong);
  border-radius: var(--radius);
  padding: 0.45rem 0.8rem;
  cursor: pointer;
}

.nav ul {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 0.15rem 0.9rem;
  margin: 0;
  padding: 0;
  justify-content: flex-end;
}

.nav a {
  display: inline-block;
  padding: 0.3rem 0;
  font-size: 0.925rem;
  text-decoration: none;
  color: var(--muted);
  border-bottom: 2px solid transparent;
}
.nav a:hover { color: var(--accent-dark); border-bottom-color: var(--line-strong); }
.nav a[aria-current="page"] { color: var(--ink); border-bottom-color: var(--accent); }

/* ---------- layout ---------- */

.page { padding: 2.25rem 0 3rem; }

.page > * { max-width: var(--measure); }
.page > .full { max-width: none; }

h1, h2, h3, h4 {
  line-height: 1.25;
  margin: 0 0 0.6rem;
  letter-spacing: -0.005em;
}

h1 { font-size: 2rem; margin-bottom: 0.9rem; }
h2 { font-size: 1.4rem; margin-top: 2.4rem; padding-top: 0.2rem; }
h3 { font-size: 1.125rem; margin-top: 1.8rem; }

p, ul, ol, dl, table { margin: 0 0 var(--step); }

ul, ol { padding-left: 1.3rem; }
li { margin-bottom: 0.4rem; }

.lede {
  font-size: 1.2rem;
  line-height: 1.55;
  color: var(--muted);
  margin-bottom: 1.6rem;
}

.eyebrow {
  text-transform: uppercase;
  letter-spacing: 0.1em;
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--olive);
  margin: 0 0 0.5rem;
}

/* ---------- boxes ---------- */

.card {
  background: var(--surface);
  border: 1px solid var(--line-strong);
  border-radius: var(--radius);
  padding: 1.25rem 1.35rem;
  margin: 0 0 1.6rem;
}

.card h2, .card h3 { margin-top: 0; }
.card > :last-child { margin-bottom: 0; }

.disclosure {
  background: var(--surface);
  border: 2px solid var(--accent);
  border-radius: var(--radius);
  padding: 1.15rem 1.3rem;
  margin: 0 0 1.8rem;
}
.disclosure p { margin-bottom: 0.7rem; }
.disclosure > :last-child { margin-bottom: 0; }
.disclosure strong { color: var(--accent-dark); }

.note {
  border-left: 4px solid var(--olive);
  background: var(--surface-alt);
  padding: 1rem 1.2rem;
  margin: 0 0 1.6rem;
  border-radius: 0 var(--radius) var(--radius) 0;
}
.note > :last-child { margin-bottom: 0; }

.watch {
  border: 1px solid var(--line-strong);
  border-top: 4px solid var(--olive);
  background: var(--surface);
  padding: 1.1rem 1.3rem;
  margin: 0 0 1.6rem;
  border-radius: var(--radius);
}
.watch > :last-child { margin-bottom: 0; }

.method {
  background: var(--surface-alt);
  border: 1px dashed var(--line-strong);
  padding: 1.1rem 1.3rem;
  margin: 0 0 1.6rem;
  border-radius: var(--radius);
  font-size: 0.98rem;
}
.method > :last-child { margin-bottom: 0; }

.ad-note {
  font-size: 0.95rem;
  color: var(--muted);
  margin: 0.55rem 0 0;
  max-width: 52ch;
}

/* ---------- link out ---------- */

.linkout {
  display: inline-block;
  background: var(--accent);
  color: #fff;
  text-decoration: none;
  font-weight: 600;
  padding: 0.7rem 1.15rem;
  border-radius: var(--radius);
  border: 1px solid var(--accent-dark);
}
.linkout:hover { background: var(--accent-dark); color: #fff; }

/* ---------- steps ---------- */

.steps {
  list-style: none;
  counter-reset: step;
  padding: 0;
  margin: 0 0 1.8rem;
}

.steps li {
  counter-increment: step;
  position: relative;
  padding: 0 0 0 3rem;
  margin-bottom: 1.15rem;
}

.steps li::before {
  content: counter(step);
  position: absolute;
  left: 0;
  top: 0.1rem;
  width: 2.1rem;
  height: 2.1rem;
  display: grid;
  place-items: center;
  background: var(--surface);
  border: 1px solid var(--accent);
  color: var(--accent-dark);
  border-radius: 50%;
  font-weight: 700;
  font-size: 0.9rem;
}

.steps h3 { margin: 0 0 0.2rem; font-size: 1.05rem; }
.steps p { margin: 0; color: var(--muted); font-size: 0.99rem; }

.checklist { list-style: none; padding: 0; }
.checklist li {
  position: relative;
  padding-left: 1.7rem;
  margin-bottom: 0.65rem;
}
.checklist li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.45rem;
  width: 0.85rem;
  height: 0.85rem;
  border: 2px solid var(--accent);
  border-radius: 2px;
}

/* ---------- tables ---------- */

.table-scroll {
  overflow-x: auto;
  margin: 0 0 1.7rem;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius);
  background: var(--surface);
}

table {
  border-collapse: collapse;
  width: 100%;
  margin: 0;
  font-size: 0.97rem;
}

caption {
  text-align: left;
  padding: 0.85rem 1rem;
  font-weight: 700;
  border-bottom: 1px solid var(--line-strong);
}

th, td {
  text-align: left;
  vertical-align: top;
  padding: 0.7rem 1rem;
  border-bottom: 1px solid var(--line);
}

thead th {
  background: var(--surface-alt);
  border-bottom: 1px solid var(--line-strong);
}

tbody tr:last-child td, tbody tr:last-child th { border-bottom: 0; }

/* ---------- definition list ---------- */

dl.terms dt { font-weight: 700; margin-top: 1rem; }
dl.terms dd { margin: 0.2rem 0 0; color: var(--muted); }

/* ---------- accordion ---------- */

details.qa {
  border: 1px solid var(--line-strong);
  border-radius: var(--radius);
  background: var(--surface);
  margin-bottom: 0.7rem;
}

details.qa summary {
  cursor: pointer;
  padding: 0.85rem 1.1rem;
  font-weight: 600;
  list-style: revert;
}

details.qa[open] summary { border-bottom: 1px solid var(--line); }
details.qa .qa-body { padding: 1rem 1.1rem; }
details.qa .qa-body > :last-child { margin-bottom: 0; }

/* ---------- contents ---------- */

.toc {
  background: var(--surface);
  border: 1px solid var(--line-strong);
  border-radius: var(--radius);
  padding: 1.05rem 1.25rem;
  margin: 0 0 2rem;
}
.toc h2 { margin: 0 0 0.6rem; font-size: 0.85rem; text-transform: uppercase; letter-spacing: 0.09em; color: var(--muted); }
.toc ol { margin: 0; padding-left: 1.2rem; }
.toc li { margin-bottom: 0.3rem; }

.pager {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  border-top: 1px solid var(--line-strong);
  padding-top: 1.2rem;
  margin-top: 2.6rem;
  font-size: 0.97rem;
}

.meta-line { color: var(--muted); font-size: 0.93rem; margin-bottom: 1.6rem; }

/* ---------- figure ---------- */

figure.diagram {
  margin: 0 0 1.8rem;
  background: var(--surface);
  border: 1px solid var(--line-strong);
  border-radius: var(--radius);
  padding: 1.1rem;
}
figure.diagram svg { display: block; width: 100%; height: auto; }
figure.diagram figcaption { font-size: 0.92rem; color: var(--muted); margin-top: 0.7rem; }

/* ---------- footer ---------- */

.site-foot {
  background: var(--surface);
  border-top: 1px solid var(--line-strong);
  padding: 2.2rem 0 2.6rem;
  font-size: 0.95rem;
  color: var(--ink);
}

.site-foot p, .site-foot address { margin: 0 0 0.35rem; font-style: normal; }
.site-foot .pub-name { font-weight: 700; font-size: 1.05rem; margin-bottom: 0.5rem; }
.site-foot .foot-links { margin: 1rem 0 0.9rem; }
.site-foot .foot-links a { margin-right: 0.15rem; }
.site-foot .tm { color: var(--muted); max-width: 70ch; margin-top: 0.9rem; }
.site-foot .reviewed { margin-top: 0.9rem; color: var(--muted); }

/* ---------- responsive ---------- */

@media (max-width: 860px) {
  .head-row { flex-wrap: wrap; }
  .nav-toggle { display: inline-block; }
  .nav {
    display: none;
    width: 100%;
    padding-bottom: 0.8rem;
  }
  .nav.is-open { display: block; }
  .nav ul { flex-direction: column; align-items: flex-start; gap: 0; }
  .nav a { padding: 0.55rem 0; width: 100%; }
  h1 { font-size: 1.7rem; }
  body { font-size: 1.03rem; }
}

@media (max-width: 380px) {
  .wrap { padding: 0 1rem; }
}