:root {
  --color-surface: #f4f4f4;
  --color-surface-alt: #ebebeb;
  --color-surface-deep: #dfdfde;
  --color-ink: #48473c;
  --color-ink-soft: #6e6c5e;
  --color-ink-muted: #898676;
  --color-line: #d5d5d3;
  --color-primary: #81773c;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #e4e2da;
  --color-accent: #c35313;
  --color-accent-ink: #ffffff;
  --color-highlight: #ebd7cc;
  --color-focus: #ba4908;
  --color-contrast-surface: #1b1a14;
  --color-contrast-ink: #e7e6e4;
  --color-contrast-line: #484742;
  --color-contrast-accent: #e86317;
  --overlay-scrim: linear-gradient(180deg, rgba(27, 26, 20, 0.35) 0%, rgba(27, 26, 20, 0.72) 55%, rgba(27, 26, 20, 0.92) 100%);
  --font-heading: "Songti SC", "Source Han Serif SC", "Noto Serif SC", SimSun, serif;
  --font-body: "PingFang SC", "Microsoft YaHei", "Source Han Sans SC", sans-serif;
  --font-mono: ui-monospace, Menlo, Consolas, monospace;
  --text-xs: 11.4px;
  --text-sm: 14.3px;
  --text-base: 16px;
  --text-lg: 20.0px;
  --text-xl: 25.0px;
  --text-2xl: 31.2px;
  --text-3xl: 39.1px;
  --text-4xl: 48.8px;
  --text-display: clamp(38px, 7.9vw, 101px);
  --text-figure: clamp(32px, 5.7vw, 73px);
  --weight-heading: 635;
  --weight-body: 400;
  --leading-body: 1.85;
  --leading-heading: 1.2;
  --tracking-heading: -0.001em;
  --radius-sm: 2px;
  --radius-md: 2px;
  --radius-lg: 3px;
  --radius-pill: 3px;
  --border-thin: 1px;
  --border-thick: 2px;
  --shadow-1: 0 1px 0 rgba(72, 71, 60, 0.12);
  --shadow-2: 0 2px 0 rgba(72, 71, 60, 0.18);
  --space-1: 8px;
  --space-2: 16px;
  --space-3: 24px;
  --space-4: 32px;
  --space-6: 48px;
  --space-8: 64px;
  --container: 1140px;
  --measure: 69ch;
  --gutter: 16px;
  --section-y: 81px;
  --section-y-lg: 113px;
}

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

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

body {
  margin: 0;
  background-color: var(--color-surface);
  background-image: radial-gradient(rgba(72, 71, 60, 0.055) 1px, transparent 1px);
  background-size: 6px 6px;
  color: var(--color-ink);
  font-family: var(--font-body);
  font-size: var(--text-base);
  font-weight: var(--weight-body);
  line-height: var(--leading-body);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
}

h1, h2, h3, h4, h5, h6 {
  margin: 0;
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
}

p { margin: 0 0 var(--space-2); }
p:last-child { margin-bottom: 0; }

ul, ol { margin: 0; padding: 0; list-style: none; }

a { color: inherit; }

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

button { font: inherit; }

::selection {
  background: var(--color-primary);
  color: var(--color-primary-ink);
}

:focus-visible {
  outline: var(--border-thick) solid var(--color-focus);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}

/* ---------- layout primitives ---------- */
.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--space-3);
}

.container--narrow { max-width: 780px; }

.section { padding-block: var(--section-y); position: relative; }
.section--lg { padding-block: var(--section-y-lg); }
.section--alt { background-color: var(--color-surface-alt); }
.section--deep { background-color: var(--color-surface-deep); }
.section--dark {
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}
.section--dark h1,
.section--dark h2,
.section--dark h3 { color: var(--color-contrast-ink); }

.cols {
  display: grid;
  gap: var(--space-3);
  grid-template-columns: 1fr;
}
.cols--2 { grid-template-columns: 1fr; }
.cols--3 { grid-template-columns: 1fr; }
.cols--4 { grid-template-columns: 1fr; }

@media (min-width: 640px) {
  .cols--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .cols--3 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .cols--4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (min-width: 960px) {
  .cols--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .cols--4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
}

.prose {
  max-width: var(--measure);
  font-size: var(--text-base);
  line-height: var(--leading-body);
  color: var(--color-ink);
}
.prose h2 {
  font-size: var(--text-2xl);
  margin: var(--space-6) 0 var(--space-2);
}
.prose h3 {
  font-size: var(--text-lg);
  margin: var(--space-4) 0 var(--space-2);
}
.prose p { margin-bottom: var(--space-2); }
.prose ul, .prose ol { margin: 0 0 var(--space-3); padding-left: var(--space-3); }
.prose li { list-style: disc; margin-bottom: var(--space-1); }
.prose a {
  color: var(--color-accent);
  text-decoration: none;
  border-bottom: var(--border-thin) solid currentColor;
}

.page-head {
  padding-block: var(--section-y-lg) var(--space-6);
  position: relative;
}
.page-head h1 {
  font-size: var(--text-4xl);
  max-width: 22ch;
}
.page-head--dark {
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}
.page-head--dark h1 { color: var(--color-contrast-ink); }

.offset-rule {
  height: var(--border-thick);
  width: 58%;
  background: var(--color-line);
  border: 0;
  margin: var(--space-4) 0;
}
.offset-rule--right { margin-left: auto; }
.offset-rule--short { width: 32%; }

/* ---------- paper system ---------- */
.paper-card {
  position: relative;
  background-color: var(--color-surface-alt);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-1);
  padding: var(--space-3);
}
.paper-card--deep { background-color: var(--color-surface-deep); }
.paper-card--gold { background-color: var(--color-primary-soft); }
.paper-card--dark {
  background-color: var(--color-contrast-surface);
  border-color: var(--color-contrast-line);
  color: var(--color-contrast-ink);
}
.paper-card--dark h1,
.paper-card--dark h2,
.paper-card--dark h3 { color: var(--color-contrast-ink); }
.paper-card--lift { transform: translateY(-4px); }
.paper-card--sink { transform: translateY(4px); }

.paper-tag {
  display: inline-block;
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-weight: 600;
  letter-spacing: 0.08em;
  line-height: 1.5;
  padding: 2px 8px;
  border-radius: var(--radius-sm);
  border: var(--border-thin) solid var(--color-line);
  background-color: var(--color-primary-soft);
  color: var(--color-ink-soft);
  white-space: nowrap;
}
.paper-tag--primary {
  background-color: var(--color-primary);
  border-color: var(--color-primary);
  color: var(--color-primary-ink);
}
.paper-tag--accent {
  background-color: var(--color-accent);
  border-color: var(--color-accent);
  color: var(--color-accent-ink);
}
.paper-tag--highlight {
  background-color: var(--color-highlight);
  border-color: var(--color-highlight);
  color: var(--color-ink);
}
.paper-tag--dark {
  background-color: var(--color-contrast-surface);
  border-color: var(--color-contrast-line);
  color: var(--color-contrast-ink);
}
.paper-tag--sticker {
  position: absolute;
  top: -10px;
  left: 14px;
  z-index: 2;
  transform: rotate(-2deg);
  box-shadow: var(--shadow-2);
}

/* ---------- buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: 10px 18px;
  border: var(--border-thin) solid transparent;
  border-radius: var(--radius-md);
  font-family: var(--font-body);
  font-size: var(--text-sm);
  font-weight: 600;
  line-height: 1.3;
  text-decoration: none;
  cursor: pointer;
  transition: transform 0.18s ease, background-color 0.18s ease,
              border-color 0.18s ease, color 0.18s ease;
}
.btn:hover { transform: translateY(-2px); }
.btn--primary {
  background-color: var(--color-primary);
  border-color: var(--color-primary);
  color: var(--color-primary-ink);
  box-shadow: var(--shadow-2);
}
.btn--accent {
  background-color: var(--color-accent);
  border-color: var(--color-accent);
  color: var(--color-accent-ink);
  box-shadow: var(--shadow-2);
}
.btn--ghost {
  background-color: transparent;
  border-color: var(--color-line);
  color: var(--color-ink);
}
.btn--ghost:hover { border-color: var(--color-accent); color: var(--color-accent); }
.btn--contrast {
  background-color: transparent;
  border-color: var(--color-contrast-line);
  color: var(--color-contrast-ink);
}
.btn--contrast:hover {
  border-color: var(--color-contrast-accent);
  color: var(--color-contrast-accent);
}

/* ---------- emphasis ---------- */
.pull-quote {
  position: relative;
  margin: var(--space-4) 0;
  padding: var(--space-3) var(--space-4) var(--space-3) var(--space-6);
  background-color: var(--color-highlight);
  border-left: var(--border-thick) solid var(--color-accent);
  border-radius: var(--radius-sm);
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  line-height: 1.6;
  color: var(--color-ink);
}
.pull-quote::before {
  content: "\201C";
  position: absolute;
  left: 12px;
  top: 6px;
  font-family: var(--font-heading);
  font-size: var(--text-3xl);
  line-height: 1;
  color: var(--color-accent);
}
.pull-quote cite {
  display: block;
  margin-top: var(--space-1);
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-style: normal;
  letter-spacing: 0.08em;
  color: var(--color-ink-soft);
}

/* ---------- breadcrumbs ---------- */
.breadcrumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 6px;
  padding-block: var(--space-2);
  font-size: var(--text-xs);
  letter-spacing: 0.05em;
  color: var(--color-ink-muted);
}
.crumb {
  color: var(--color-ink-soft);
  text-decoration: none;
  border-bottom: var(--border-thin) solid transparent;
  transition: color 0.18s ease, border-color 0.18s ease;
}
.crumb:hover { color: var(--color-accent); border-bottom-color: var(--color-accent); }
.crumb-sep { color: var(--color-line); }

/* ---------- media frames ---------- */
.media-frame {
  position: relative;
  overflow: hidden;
  aspect-ratio: 16 / 9;
  background-color: var(--color-surface-deep);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-1);
}
.media-frame--wide { aspect-ratio: 21 / 9; }
.media-frame--tall { aspect-ratio: 3 / 4; }
.media-frame--portrait { aspect-ratio: 4 / 5; }
.media-frame--square { aspect-ratio: 1 / 1; }
.media-frame > img,
.media-frame > svg {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}
.media-frame__scrim {
  position: absolute;
  inset: 0;
  background: var(--overlay-scrim);
  pointer-events: none;
}
.media-frame__cap {
  position: absolute;
  left: var(--space-3);
  right: var(--space-3);
  bottom: var(--space-3);
  color: var(--color-contrast-ink);
  font-size: var(--text-sm);
  line-height: 1.5;
}
.media-frame__cap .paper-tag { margin-bottom: var(--space-1); }

/* ---------- motion ---------- */
.reveal {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 0.55s ease, transform 0.55s ease;
}
.reveal.is-visible { opacity: 1; transform: translateY(0); }
.reveal--d1 { transition-delay: 0.08s; }
.reveal--d2 { transition-delay: 0.16s; }
.reveal--d3 { transition-delay: 0.24s; }
.reveal--d4 { transition-delay: 0.32s; }

/* ---------- header ---------- */
.skip-link {
  position: absolute;
  left: var(--space-2);
  top: -72px;
  z-index: 120;
  padding: 10px 16px;
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  font-size: var(--text-sm);
  text-decoration: none;
  border-radius: var(--radius-md);
  transition: top 0.18s ease;
}
.skip-link:focus { top: var(--space-2); }

.site-header {
  position: sticky;
  top: 0;
  z-index: 90;
  background-color: color-mix(in srgb, var(--color-surface) 90%, transparent);
  backdrop-filter: blur(8px);
  border-bottom: var(--border-thin) solid var(--color-line);
  transition: background-color 0.22s ease, box-shadow 0.22s ease;
}
.site-header[data-stuck] {
  background-color: color-mix(in srgb, var(--color-surface) 97%, transparent);
  box-shadow: var(--shadow-2);
}

.header-inner {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding: var(--space-2) var(--space-3);
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: var(--color-ink);
}
.brand-mark {
  display: grid;
  place-items: center;
  width: 34px;
  height: 34px;
  flex: 0 0 auto;
  background-color: var(--color-primary);
  color: var(--color-primary-ink);
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  line-height: 1;
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow-2);
  transform: rotate(-3deg);
}
.brand-text { display: flex; flex-direction: column; }
.brand-name {
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  line-height: 1.15;
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
}
.brand-tag {
  align-self: flex-start;
  margin-top: 3px;
  padding: 1px 6px;
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  color: var(--color-ink-soft);
  background-color: var(--color-primary-soft);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
  transform: rotate(-1.5deg);
}

.nav-toggle {
  display: none;
  align-items: center;
  gap: 8px;
  padding: 7px 12px;
  background-color: transparent;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
  color: var(--color-ink);
  font-size: var(--text-sm);
  font-weight: 600;
  cursor: pointer;
  transition: border-color 0.18s ease, color 0.18s ease;
}
.nav-toggle:hover { border-color: var(--color-accent); color: var(--color-accent); }
.nav-toggle[aria-expanded="true"] {
  background-color: var(--color-primary);
  border-color: var(--color-primary);
  color: var(--color-primary-ink);
}
.nav-toggle-bars {
  display: block;
  width: 16px;
  height: 2px;
  background-color: currentColor;
  box-shadow: 0 5px 0 currentColor, 0 -5px 0 currentColor;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: var(--space-4);
}
.nav-list {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}
.nav-link {
  position: relative;
  display: inline-block;
  padding: 4px 0;
  font-size: var(--text-sm);
  color: var(--color-ink);
  text-decoration: none;
  transition: color 0.18s ease;
}
.nav-link::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -2px;
  width: 100%;
  height: var(--border-thick);
  background-color: var(--color-accent);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.22s ease;
}
.nav-link:hover { color: var(--color-accent); }
.nav-link:hover::after { transform: scaleX(1); }
.nav-link[aria-current="page"] {
  color: var(--color-accent);
  font-weight: 600;
}
.nav-link[aria-current="page"]::after { transform: scaleX(1); }

.header-cta {
  padding: 8px 14px;
  font-size: var(--text-sm);
  font-weight: 600;
  text-decoration: none;
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-radius: var(--radius-md);
  border-bottom: var(--border-thick) solid var(--color-primary);
  transition: transform 0.18s ease, background-color 0.18s ease,
              border-color 0.18s ease, color 0.18s ease;
}
.header-cta:hover {
  transform: translateY(-2px);
  background-color: var(--color-primary);
  color: var(--color-primary-ink);
  border-bottom-color: var(--color-accent);
}

.header-progress {
  position: absolute;
  left: 0;
  bottom: 0;
  display: block;
  width: 100%;
  height: var(--border-thick);
  background: linear-gradient(90deg, var(--color-primary), var(--color-accent));
  transform: scaleX(0);
  transform-origin: left;
  pointer-events: none;
}

/* ---------- footer ---------- */
.site-footer {
  position: relative;
  padding-block: var(--space-8) var(--space-4);
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}
.site-footer::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: var(--border-thick);
  background: linear-gradient(
    90deg,
    var(--color-primary) 0 32%,
    var(--color-accent) 32% 52%,
    var(--color-contrast-accent) 52% 100%
  );
}

.footer-inner {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--space-3);
}

.footer-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-4) var(--space-3);
}
@media (min-width: 720px) {
  .footer-grid { grid-template-columns: repeat(12, minmax(0, 1fr)); }
  .footer-col--brand { grid-column: span 12; }
  .footer-col--nav { grid-column: span 4; }
  .footer-col--legal { grid-column: span 3; }
  .footer-col--contact { grid-column: span 5; }
}
@media (min-width: 1000px) {
  .footer-col--brand { grid-column: span 4; }
  .footer-col--nav { grid-column: span 3; }
  .footer-col--legal { grid-column: span 2; }
  .footer-col--contact { grid-column: span 3; }
}

.footer-brand {
  position: relative;
  padding: var(--space-3);
  background-color: color-mix(in srgb, var(--color-contrast-ink) 7%, transparent);
  border: var(--border-thin) solid var(--color-contrast-line);
  border-radius: var(--radius-md);
}
.footer-sticker {
  top: -10px;
  left: auto;
  right: 14px;
  transform: rotate(2deg);
}
.footer-mark {
  display: inline-grid;
  place-items: center;
  width: 32px;
  height: 32px;
  margin-bottom: var(--space-2);
  background-color: var(--color-primary);
  color: var(--color-primary-ink);
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  line-height: 1;
  border-radius: var(--radius-sm);
  transform: rotate(-3deg);
}
.footer-brand-name {
  margin: 0;
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  line-height: 1.25;
  color: var(--color-contrast-ink);
}
.footer-brand-note {
  margin: var(--space-1) 0 0;
  font-size: var(--text-sm);
  line-height: 1.7;
  color: color-mix(in srgb, var(--color-contrast-ink) 78%, transparent);
}
.footer-icp {
  margin: var(--space-2) 0 0;
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: color-mix(in srgb, var(--color-contrast-ink) 62%, transparent);
}

.footer-title {
  margin: 0 0 var(--space-2);
  padding-bottom: 6px;
  font-family: var(--font-heading);
  font-size: var(--text-sm);
  font-weight: var(--weight-heading);
  letter-spacing: 0.12em;
  color: var(--color-contrast-accent);
  border-bottom: var(--border-thin) solid var(--color-contrast-line);
}

.footer-list { display: flex; flex-direction: column; gap: 9px; }
.footer-list--plain {
  font-size: var(--text-sm);
  line-height: 1.7;
  color: color-mix(in srgb, var(--color-contrast-ink) 80%, transparent);
}

.footer-link {
  font-size: var(--text-sm);
  color: color-mix(in srgb, var(--color-contrast-ink) 88%, transparent);
  text-decoration: none;
  border-bottom: var(--border-thin) solid transparent;
  transition: color 0.18s ease, border-color 0.18s ease;
}
.footer-link:hover {
  color: var(--color-contrast-accent);
  border-bottom-color: var(--color-contrast-accent);
}

.footer-bottom {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: var(--space-2) var(--space-4);
  margin-top: var(--space-8);
  padding-top: var(--space-3);
  border-top: var(--border-thin) solid var(--color-contrast-line);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: color-mix(in srgb, var(--color-contrast-ink) 66%, transparent);
}
.footer-copy, .footer-note { margin: 0; }

/* ---------- optional back-to-top ---------- */
[data-to-top] {
  position: fixed;
  right: var(--space-3);
  bottom: var(--space-3);
  z-index: 80;
  opacity: 0;
  pointer-events: none;
  transform: translateY(8px);
  transition: opacity 0.22s ease, transform 0.22s ease;
}
[data-to-top][data-visible] {
  opacity: 1;
  pointer-events: auto;
  transform: translateY(0);
}

/* ---------- responsive header ---------- */
@media (max-width: 900px) {
  .nav-toggle { display: inline-flex; }

  .site-nav {
    position: absolute;
    top: calc(100% + 1px);
    left: var(--space-3);
    right: var(--space-3);
    display: none;
    flex-direction: column;
    align-items: stretch;
    gap: var(--space-3);
    padding: var(--space-3);
    background-color: var(--color-surface-alt);
    border: var(--border-thin) solid var(--color-line);
    border-radius: 0 0 var(--radius-md) var(--radius-md);
    box-shadow: var(--shadow-2);
  }
  .site-nav[data-open] { display: flex; }

  .nav-list { flex-direction: column; align-items: stretch; gap: 0; }
  .nav-item + .nav-item { border-top: var(--border-thin) solid var(--color-line); }
  .nav-link { display: block; padding: 12px 2px; }
  .nav-link::after { display: none; }

  .header-cta { align-self: flex-start; }
}

@media (max-width: 520px) {
  .brand-name { font-size: var(--text-base); }
  .brand-tag { font-size: 10px; }
  .header-inner { padding-inline: var(--space-2); }
  .site-nav { left: var(--space-2); right: var(--space-2); }
  .page-head { padding-block: var(--section-y) var(--space-4); }
}

/* ---------- reduced motion ---------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *,
  *::before,
  *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }
  .reveal { opacity: 1; transform: none; }
}