/* ============================================================
   长乐坊 站点共享样式 /assets/site.css
   纸页、印章、索引签与装订线
   ============================================================ */

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

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

body,
h1, h2, h3, h4, h5, h6,
p, figure, blockquote, dl, dd, ul, ol {
  margin: 0;
}

ul[class],
ol[class] {
  padding: 0;
  list-style: none;
}

img, picture, svg, video {
  max-width: 100%;
  display: block;
}

button, input, select, textarea {
  font: inherit;
  color: inherit;
}

button {
  background: none;
  border: 0;
  cursor: pointer;
}

a { color: inherit; }

/* ---------- tokens ---------- */
:root {
  --paper: #F7F0E3;
  --card: #FFF9EF;
  --ink: #2B1F1A;
  --cinnabar: #B53A2D;
  --gold: #D9A441;
  --celadon: #6F8F7A;
  --celadon-deep: #3F5F4D;
  --gold-pale: #F0D9A8;
  --umber: #7A4B32;
  --mist: #C9D3C5;
  --orange: #E56B3F;

  --font-title: "Noto Sans SC", "Source Han Sans SC", "PingFang SC", sans-serif;
  --font-body: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-mono: "JetBrains Mono", "SFMono-Regular", Menlo, Consolas, monospace;

  --line: 1px solid rgba(122, 75, 50, 0.28);
  --line-strong: 1px solid var(--umber);
  --radius: 2px;

  --container: 1180px;
  --header-h: 68px;
  --gutter: clamp(16px, 4vw, 40px);

  --dur-fast: 160ms;
  --dur-mid: 260ms;
  --ease: cubic-bezier(0.2, 0.7, 0.3, 1);
}

/* ---------- base ---------- */
body {
  background-color: var(--paper);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 17px;
  line-height: 1.75;
  letter-spacing: 0.01em;
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4 {
  font-family: var(--font-title);
  font-weight: 800;
  line-height: 1.22;
  letter-spacing: 0.04em;
  color: var(--ink);
}

h1 { font-size: clamp(2.6rem, 7vw, 5.6rem); }
h2 { font-size: clamp(1.8rem, 3.6vw, 2.8rem); }
h3 { font-size: clamp(1.15rem, 2vw, 1.5rem); }
h4 { font-size: 1.05rem; letter-spacing: 0.06em; }

p { max-width: 68ch; }

strong { font-weight: 700; }

a {
  text-decoration-thickness: 1px;
  text-underline-offset: 0.22em;
}

:focus-visible {
  outline: 3px solid var(--cinnabar);
  outline-offset: 3px;
  border-radius: 1px;
}

::selection {
  background: var(--cinnabar);
  color: var(--card);
}

/* ---------- layout helpers ---------- */
.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.container--narrow {
  max-width: 820px;
}

.section {
  padding-block: clamp(40px, 7vw, 88px);
}

.section--tint {
  background: var(--mist);
  border-block: var(--line);
}

.section--ink {
  background: var(--ink);
  color: var(--card);
}

.section--ink h2,
.section--ink h3 { color: var(--card); }

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

/* ---------- skip link ---------- */
.skip-link {
  position: fixed;
  top: 8px;
  left: 8px;
  z-index: 200;
  transform: translateY(-180%);
  background: var(--ink);
  color: var(--card);
  padding: 10px 16px;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.06em;
  text-decoration: none;
  border: var(--line-strong);
  transition: transform var(--dur-fast) var(--ease);
}

.skip-link:focus {
  transform: translateY(0);
}

/* ---------- header ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(247, 240, 227, 0);
  color: var(--card);
  border-bottom: 1px solid rgba(255, 249, 239, 0.22);
  transition: background-color var(--dur-mid) var(--ease),
              color var(--dur-mid) var(--ease),
              border-color var(--dur-mid) var(--ease),
              box-shadow var(--dur-mid) var(--ease);
}

.site-header[data-scrolled="true"] {
  background: var(--paper);
  color: var(--ink);
  border-bottom-color: rgba(122, 75, 50, 0.45);
  box-shadow: 0 1px 0 rgba(122, 75, 50, 0.15), 0 8px 24px -22px rgba(43, 31, 26, 0.9);
}

/* 首屏之上透明态：为页面首屏预留深色底时的可读性 */
.site-header:not([data-scrolled="true"]) .brand-tagline,
.site-header:not([data-scrolled="true"]) .primary-nav-list a {
  color: var(--card);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  min-height: var(--header-h);
  padding-block: 10px;
}

.brand-lockup {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
  min-height: 44px;
}

.brand-seal {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  writing-mode: vertical-rl;
  text-orientation: upright;
  width: 34px;
  height: 44px;
  background: var(--cinnabar);
  color: var(--card);
  font-family: var(--font-title);
  font-weight: 800;
  font-size: 13px;
  letter-spacing: 0.14em;
  border-radius: 1px;
  box-shadow: inset 0 0 0 1px rgba(255, 249, 239, 0.35);
  flex: 0 0 auto;
}

.brand-text {
  display: flex;
  flex-direction: column;
  line-height: 1.24;
}

.brand-name {
  font-family: var(--font-title);
  font-weight: 800;
  font-size: 1.24rem;
  letter-spacing: 0.16em;
}

.brand-tagline {
  font-size: 11px;
  letter-spacing: 0.1em;
  color: var(--gold-pale);
  white-space: nowrap;
}

.site-header[data-scrolled="true"] .brand-tagline {
  color: var(--umber);
}

/* nav */
.primary-nav {
  display: flex;
  align-items: center;
  gap: clamp(12px, 2vw, 28px);
}

.primary-nav-list {
  display: flex;
  align-items: center;
  gap: clamp(4px, 1.4vw, 20px);
}

.primary-nav-list a {
  display: inline-block;
  position: relative;
  padding: 9px 4px;
  font-size: 0.95rem;
  font-weight: 500;
  letter-spacing: 0.06em;
  text-decoration: none;
  color: var(--ink);
  transition: color var(--dur-fast) var(--ease);
}

.site-header:not([data-scrolled="true"]) .primary-nav-list a {
  color: var(--card);
}

.primary-nav-list a::after {
  content: "";
  position: absolute;
  left: 4px;
  right: 4px;
  bottom: 3px;
  height: 2px;
  background: var(--gold);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform var(--dur-fast) var(--ease);
}

.primary-nav-list a:hover::after,
.primary-nav-list a:focus-visible::after {
  transform: scaleX(1);
}

.primary-nav-list a[aria-current="page"] {
  color: var(--cinnabar);
  font-weight: 700;
}

.site-header:not([data-scrolled="true"]) .primary-nav-list a[aria-current="page"] {
  color: var(--gold-pale);
}

.primary-nav-list a[aria-current="page"]::after {
  transform: scaleX(1);
  background: var(--cinnabar);
  height: 2px;
}

.site-header:not([data-scrolled="true"]) .primary-nav-list a[aria-current="page"]::after {
  background: var(--gold);
}

.header-meta {
  display: flex;
  align-items: center;
  gap: 10px;
}

.version-badge {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  padding: 4px 8px;
  border: 1px solid rgba(217, 164, 65, 0.85);
  color: var(--gold-pale);
  background: rgba(43, 31, 26, 0.28);
  border-radius: 1px;
  white-space: nowrap;
}

.site-header[data-scrolled="true"] .version-badge {
  color: var(--umber);
  background: var(--gold-pale);
  border-color: var(--umber);
}

.help-pill {
  display: inline-block;
  padding: 7px 13px;
  font-size: 0.82rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-decoration: none;
  color: var(--card);
  background: var(--cinnabar);
  border: 1px solid var(--cinnabar);
  border-radius: 1px;
  white-space: nowrap;
  transition: background-color var(--dur-fast) var(--ease),
              color var(--dur-fast) var(--ease);
}

.help-pill:hover,
.help-pill:focus-visible {
  background: var(--gold-pale);
  color: var(--ink);
  border-color: var(--umber);
}

/* nav toggle */
.nav-toggle {
  display: none;
  align-items: center;
  gap: 8px;
  min-height: 44px;
  padding: 6px 10px;
  border: 1px solid currentColor;
  border-radius: 1px;
  color: inherit;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
}

.nav-toggle-bars {
  position: relative;
  display: block;
  width: 18px;
  height: 2px;
  background: currentColor;
  box-shadow: 0 -6px 0 currentColor, 0 6px 0 currentColor;
  transition: box-shadow var(--dur-fast) var(--ease),
              background-color var(--dur-fast) var(--ease),
              transform var(--dur-fast) var(--ease);
}

.site-header[data-open="true"] .nav-toggle-bars {
  background: transparent;
  box-shadow: none;
  transform: rotate(45deg);
}

.site-header[data-open="true"] .nav-toggle-bars::after {
  content: "";
  position: absolute;
  inset: 0;
  background: currentColor;
  transform: rotate(90deg);
}

.nav-toggle-text { letter-spacing: 0.12em; }

/* ---------- buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 13px 24px;
  min-height: 46px;
  font-family: var(--font-title);
  font-size: 0.95rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-decoration: none;
  border: 1px solid var(--ink);
  border-radius: var(--radius);
  background: var(--card);
  color: var(--ink);
  cursor: pointer;
  transition: background-color var(--dur-fast) var(--ease),
              color var(--dur-fast) var(--ease),
              border-color var(--dur-fast) var(--ease),
              transform var(--dur-fast) var(--ease);
}

.btn:hover,
.btn:focus-visible {
  transform: translateY(-1px);
}

.btn--primary {
  background: var(--cinnabar);
  border-color: var(--cinnabar);
  color: var(--card);
}

.btn--primary:hover,
.btn--primary:focus-visible {
  background: var(--ink);
  border-color: var(--ink);
  color: var(--card);
}

.btn--ghost {
  background: transparent;
  border-color: var(--umber);
  color: var(--umber);
}

.btn--ghost:hover,
.btn--ghost:focus-visible {
  background: var(--gold-pale);
  color: var(--ink);
  border-color: var(--umber);
}

.btn--sm {
  padding: 9px 16px;
  min-height: 40px;
  font-size: 0.85rem;
}

/* ---------- breadcrumbs ---------- */
.breadcrumbs {
  padding-block: 18px 0;
}

.breadcrumbs-list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 6px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--umber);
}

.breadcrumbs-list li {
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.breadcrumbs-list li + li::before {
  content: "›";
  color: var(--gold);
}

.breadcrumbs-list a {
  text-decoration: none;
  border-bottom: 1px solid rgba(122, 75, 50, 0.4);
}

.breadcrumbs-list a:hover { color: var(--cinnabar); }

/* ---------- chapter mark ---------- */
.chapter-mark {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 18px;
}

.chapter-num {
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.18em;
  color: var(--umber);
  white-space: nowrap;
}

.chapter-rule {
  display: block;
  width: 34px;
  height: 3px;
  background: var(--cinnabar);
  flex: 0 0 auto;
}

.chapter-title {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.16em;
  color: var(--cinnabar);
  text-transform: none;
}

/* ---------- grid ---------- */
.grid {
  display: grid;
  gap: clamp(16px, 2.4vw, 28px);
  grid-template-columns: repeat(12, minmax(0, 1fr));
}

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

/* ---------- cards ---------- */
.paper-card,
.panel-card {
  position: relative;
  background: var(--card);
  border: var(--line-strong);
  border-radius: var(--radius);
  padding: clamp(18px, 2.6vw, 30px);
  box-shadow: 4px 5px 0 rgba(122, 75, 50, 0.13);
}

.paper-card--tint {
  background: var(--mist);
  box-shadow: 4px 5px 0 rgba(63, 95, 77, 0.22);
}

.paper-card h3,
.panel-card h3 {
  margin-bottom: 8px;
}

/* ---------- tags ---------- */
.tag {
  display: inline-flex;
  align-items: center;
  padding: 3px 9px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.1em;
  border: 1px solid var(--umber);
  background: var(--paper);
  color: var(--umber);
  border-radius: 1px;
  white-space: nowrap;
}

.tag--red {
  background: var(--cinnabar);
  border-color: var(--cinnabar);
  color: var(--card);
}

.tag--gold {
  background: var(--gold-pale);
  border-color: var(--umber);
  color: var(--ink);
}

.tag--green {
  background: var(--celadon);
  border-color: var(--celadon-deep);
  color: var(--card);
}

/* ---------- index tags / filter ---------- */
.index-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  padding: 12px 0;
}

.index-tag {
  display: inline-flex;
  align-items: center;
  padding: 7px 14px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--ink);
  background: transparent;
  border: 1px solid var(--celadon);
  border-radius: 1px;
  cursor: pointer;
  transition: background-color var(--dur-fast) var(--ease),
              color var(--dur-fast) var(--ease),
              border-color var(--dur-fast) var(--ease);
}

.index-tag:hover {
  border-color: var(--cinnabar);
  color: var(--cinnabar);
}

.index-tag[aria-pressed="true"] {
  background: var(--cinnabar);
  border-color: var(--cinnabar);
  color: var(--card);
}

/* ---------- fold group ---------- */
.fold-group {
  border-top: var(--line);
}

.fold-item {
  border-bottom: var(--line);
}

.fold-trigger {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 16px;
  width: 100%;
  padding: 18px 0;
  text-align: left;
  font-family: var(--font-title);
  font-size: 1.05rem;
  font-weight: 700;
  letter-spacing: 0.03em;
  color: var(--ink);
}

.fold-trigger::after {
  content: "+";
  flex: 0 0 auto;
  width: 26px;
  height: 26px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-size: 18px;
  line-height: 1;
  color: var(--card);
  background: var(--cinnabar);
  border-radius: 1px;
  transition: background-color var(--dur-fast) var(--ease);
}

.fold-trigger[aria-expanded="true"]::after {
  content: "−";
  background: var(--ink);
}

.fold-trigger:hover::after {
  background: var(--umber);
}

.fold-panel {
  padding: 0 0 20px;
  font-size: 0.98rem;
  color: var(--ink);
}

.fold-panel > p {
  margin-bottom: 10px;
}

.fold-panel[hidden] {
  display: none;
}

/* ---------- timeline ---------- */
.timeline {
  position: relative;
  margin-top: 28px;
  padding-left: 22px;
  border-left: 2px solid rgba(122, 75, 50, 0.3);
}

.timeline-item {
  position: relative;
  padding: 0 0 26px 18px;
}

.timeline-dot {
  position: absolute;
  left: -31px;
  top: 8px;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--gold);
  border: 2px solid var(--paper);
  box-shadow: 0 0 0 1px var(--umber);
}

.timeline-item.is-current .timeline-dot {
  background: var(--orange);
  box-shadow: 0 0 0 2px var(--orange);
}

/* ---------- media frames ---------- */
.media-frame {
  position: relative;
  display: block;
  width: 100%;
  aspect-ratio: 4 / 3;
  overflow: hidden;
  background-color: var(--mist);
  background-image: repeating-linear-gradient(
    135deg,
    rgba(122, 75, 50, 0.1) 0 1px,
    transparent 1px 10px
  );
  border: var(--line-strong);
  border-radius: var(--radius);
}

.media-frame--wide { aspect-ratio: 16 / 9; }
.media-frame--tall { aspect-ratio: 3 / 4; }

.media-frame > img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.media-frame::after {
  content: "索引图";
  position: absolute;
  left: 10px;
  bottom: 10px;
  padding: 3px 8px;
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.12em;
  color: var(--card);
  background: rgba(43, 31, 26, 0.72);
  pointer-events: none;
}

.media-frame:has(img)::after { content: none; }

.media-figure {
  margin: 0;
}

.media-caption {
  display: block;
  margin-top: 8px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.06em;
  color: var(--umber);
}

/* ---------- reading progress ---------- */
.reading-progress {
  position: fixed;
  top: 0;
  left: 0;
  z-index: 150;
  width: 100%;
  height: 3px;
  background: transparent;
  pointer-events: none;
}

.reading-progress::before {
  content: "";
  display: block;
  height: 100%;
  width: var(--progress, 0%);
  background: linear-gradient(90deg, var(--gold), var(--cinnabar));
  transition: width 80ms linear;
}

/* ---------- reveal ---------- */
.reveal {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity 300ms var(--ease), transform 300ms var(--ease);
}

.reveal.is-visible {
  opacity: 1;
  transform: none;
}

/* ---------- back to top ---------- */
.back-to-top {
  position: fixed;
  right: clamp(12px, 3vw, 28px);
  bottom: clamp(12px, 3vw, 28px);
  z-index: 90;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 10px 14px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  color: var(--card);
  background: var(--ink);
  border: 1px solid var(--gold);
  border-radius: 1px;
  opacity: 0;
  visibility: hidden;
  transform: translateY(8px);
  transition: opacity var(--dur-fast) var(--ease),
              transform var(--dur-fast) var(--ease),
              visibility var(--dur-fast) var(--ease);
}

.back-to-top.is-visible {
  opacity: 1;
  visibility: visible;
  transform: none;
}

/* ---------- footer ---------- */
.site-footer {
  margin-top: clamp(48px, 8vw, 96px);
  background: var(--ink);
  color: var(--card);
  padding-block: clamp(36px, 6vw, 64px) clamp(20px, 3vw, 32px);
  border-top: 6px solid var(--cinnabar);
}

.footer-top {
  display: grid;
  grid-template-columns: minmax(0, 1.15fr) minmax(0, 1.1fr) minmax(0, 1fr);
  gap: clamp(24px, 4vw, 48px);
  align-items: start;
}

.footer-brand-line {
  font-family: var(--font-title);
  font-weight: 800;
  font-size: 1.18rem;
  letter-spacing: 0.1em;
  color: var(--gold-pale);
  max-width: none;
}

.footer-intro {
  margin-block: 12px 20px;
  font-size: 0.94rem;
  line-height: 1.8;
  color: #E8DDCB;
}

.footer-columns {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: clamp(16px, 3vw, 32px);
}

.footer-col-title {
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.18em;
  color: var(--gold);
  margin-bottom: 14px;
  padding-bottom: 8px;
  border-bottom: 1px solid rgba(217, 164, 65, 0.4);
}

.footer-list {
  display: flex;
  flex-direction: column;
  gap: 9px;
  font-size: 0.93rem;
}

.footer-list a {
  text-decoration: none;
  color: #E8DDCB;
  border-bottom: 1px solid transparent;
  transition: color var(--dur-fast) var(--ease),
              border-color var(--dur-fast) var(--ease);
}

.footer-list a:hover,
.footer-list a:focus-visible {
  color: var(--gold-pale);
  border-bottom-color: var(--gold);
}

.footer-contact-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
  font-size: 0.9rem;
  color: #E8DDCB;
}

.footer-contact-list a {
  text-decoration: none;
  color: var(--card);
  border-bottom: 1px solid rgba(217, 164, 65, 0.5);
  word-break: break-word;
}

.footer-contact-list a:hover,
.footer-contact-list a:focus-visible {
  color: var(--gold-pale);
}

.contact-key {
  display: inline-block;
  min-width: 42px;
  margin-right: 8px;
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.14em;
  color: var(--gold);
  text-transform: uppercase;
}

.footer-note {
  margin-top: 14px;
  font-size: 0.8rem;
  line-height: 1.7;
  color: #C9BBA6;
}

.footer-legal {
  margin-top: clamp(24px, 4vw, 40px);
}

.footer-rule {
  height: 0;
  border-top: 1px solid rgba(217, 164, 65, 0.38);
  margin-bottom: 16px;
}

.footer-legal-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px 20px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.06em;
  color: #BCAE99;
}

.footer-legal-item { max-width: none; }

.footer-legal-link {
  color: #E8DDCB;
  text-decoration: none;
  border-bottom: 1px solid rgba(217, 164, 65, 0.45);
}

.footer-legal-link:hover,
.footer-legal-link:focus-visible {
  color: var(--gold-pale);
}

/* ---------- responsive ---------- */
@media (max-width: 1024px) {
  .footer-top {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  }
  .footer-contact {
    grid-column: 1 / -1;
  }
  .grid {
    grid-template-columns: repeat(6, minmax(0, 1fr));
  }
  .col-span-8,
  .col-span-7,
  .col-span-6 { grid-column: span 6; }
  .col-span-5,
  .col-span-4,
  .col-span-3 { grid-column: span 3; }
}

@media (max-width: 860px) {
  :root { --header-h: 60px; }

  .nav-toggle { display: inline-flex; }

  .primary-nav {
    position: absolute;
    left: 0;
    right: 0;
    top: 100%;
    z-index: 120;
    display: none;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: 8px var(--gutter) 22px;
    background: var(--paper);
    color: var(--ink);
    border-bottom: 3px solid var(--cinnabar);
    box-shadow: 0 18px 30px -24px rgba(43, 31, 26, 0.95);
  }

  .site-header[data-open="true"] .primary-nav {
    display: flex;
  }

  .primary-nav-list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    width: 100%;
  }

  .primary-nav-list a {
    display: block;
    padding: 14px 2px;
    font-size: 1rem;
    color: var(--ink);
    border-bottom: var(--line);
  }

  .site-header:not([data-scrolled="true"]) .primary-nav-list a {
    color: var(--ink);
  }

  .primary-nav-list a::after { display: none; }

  .primary-nav-list a[aria-current="page"],
  .site-header:not([data-scrolled="true"]) .primary-nav-list a[aria-current="page"] {
    color: var(--cinnabar);
    background: rgba(181, 58, 45, 0.07);
    padding-left: 10px;
  }

  .header-meta {
    margin-top: 16px;
    flex-wrap: wrap;
  }

  .site-header:not([data-scrolled="true"]) .version-badge {
    color: var(--umber);
    background: var(--gold-pale);
    border-color: var(--umber);
  }

  .site-header[data-open="true"] {
    background: var(--paper);
    color: var(--ink);
    border-bottom-color: var(--umber);
  }

  .footer-top {
    grid-template-columns: 1fr;
  }
  .footer-contact { grid-column: auto; }
}

@media (max-width: 640px) {
  body { font-size: 16px; }

  .brand-tagline { display: none; }

  .grid {
    grid-template-columns: 1fr;
  }
  .col-span-12,
  .col-span-8,
  .col-span-7,
  .col-span-6,
  .col-span-5,
  .col-span-4,
  .col-span-3 { grid-column: 1 / -1; }

  .footer-columns {
    grid-template-columns: 1fr;
  }

  .footer-legal-row {
    flex-direction: column;
    align-items: flex-start;
    gap: 6px;
  }

  .back-to-top {
    padding: 8px 11px;
    font-size: 10px;
  }
}

/* ---------- motion preference ---------- */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }

  .reveal {
    opacity: 1;
    transform: none;
  }

  .btn:hover,
  .btn:focus-visible {
    transform: none;
  }

  .reading-progress::before { transition: none; }
}

@media print {
  .site-header,
  .site-footer,
  .back-to-top,
  .reading-progress,
  .nav-toggle { display: none; }
  body { background: #fff; color: #000; }
}