/* ==========================================================================
   Vaciov Labs — Archaeometry & Cultural Heritage Conservation Science (科技考古)
   Design System inspired by Getty Conservation Institute, British Museum
   Scientific Research, ICCROM, and modern editorial design systems.
   ========================================================================== */

:root {
  /* Archival Warm Stone & Parchment Surfaces */
  --bg-parchment: #f6f2eb;
  --bg-alabaster: #efe9df;
  --bg-card: #faf8f4;
  --bg-card-hover: #ffffff;

  /* Cool Laboratory & Microscope Stage Dark Surfaces */
  --lab-slate: #171d20;
  --lab-slate-elevated: #1f272b;
  --lab-slate-border: #334046;

  /* Clay, Terracotta, Wood & Mineral Accents */
  --clay-terracotta: #a84a2b;
  --clay-terracotta-deep: #87371d;
  --clay-terracotta-soft: #f5e6e0;
  --clay-ochre: #c47d3b;

  --wood-heartwood: #5c3d28;
  --wood-grain: #8a6548;
  --wood-soft: #efe5dc;

  --mineral-teal: #2a5c63;
  --mineral-teal-light: #73b3bd;
  --mineral-teal-soft: #e3eff1;

  /* Typography Colors */
  --ink-primary: #181614;
  --ink-secondary: #3f3a34;
  --ink-muted: #696158;
  --ink-on-dark: #f4f0e8;
  --ink-on-dark-muted: #b7b0a4;

  /* Hairline Rules & Borders */
  --rule-light: #dcd4c6;
  --rule-strong: #bfb3a0;

  /* System Typography Stacks (Zero External CDNs) */
  --font-serif: "Iowan Old Style", "Palatino Linotype", Palatino, "Book Antiqua",
    Charter, "Bitstream Charter", Georgia, "Songti SC", "STSong",
    "Noto Serif CJK SC", serif;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
    "Helvetica Neue", Arial, "PingFang SC", "Hiragino Sans GB",
    "Microsoft YaHei", sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas,
    "Liberation Mono", monospace;

  /* Layout & Spacing */
  --container-max: 1200px;
  --header-height: 4.5rem;
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;

  /* Shadows */
  --shadow-subtle: 0 2px 8px rgba(24, 22, 20, 0.04);
  --shadow-elevated: 0 12px 30px -6px rgba(24, 22, 20, 0.09);
  --shadow-dark: 0 18px 40px -10px rgba(10, 14, 16, 0.35);

  /* Motion */
  --ease-out-expo: cubic-bezier(0.16, 1, 0.3, 1);
}

/* ==========================================================================
   Reset & Base
   ========================================================================== */

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-height) + 1rem);
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: 1rem;
  line-height: 1.68;
  color: var(--ink-primary);
  background-color: var(--bg-parchment);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

h1,
h2,
h3,
h4,
p,
figure,
dl,
dd {
  margin: 0;
}

ul,
ol {
  margin: 0;
  padding: 0;
}

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

a {
  color: var(--clay-terracotta);
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
  transition: color 0.2s ease, background-color 0.2s ease, border-color 0.2s ease;
}

a:hover {
  color: var(--clay-terracotta-deep);
}

a:focus-visible,
button:focus-visible {
  outline: 2px solid var(--mineral-teal);
  outline-offset: 3px;
}

/* Skip Link */
.skip-link {
  position: absolute;
  top: -100%;
  left: 1rem;
  z-index: 1000;
  padding: 0.75rem 1.25rem;
  background-color: var(--lab-slate);
  color: var(--ink-on-dark);
  font-family: var(--font-mono);
  font-size: 0.85rem;
  font-weight: 600;
  text-decoration: none;
  border-radius: var(--radius-sm);
}

.skip-link:focus {
  top: 1rem;
}

/* Container */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin-inline: auto;
  padding-inline: 1.5rem;
}

/* ==========================================================================
   Top Institutional Classification Bar
   ========================================================================== */

.top-bar {
  background-color: var(--lab-slate);
  color: var(--ink-on-dark-muted);
  border-bottom: 1px solid var(--lab-slate-border);
  font-family: var(--font-mono);
  font-size: 0.74rem;
  letter-spacing: 0.05em;
  padding-block: 0.45rem;
}

.top-bar-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}

.top-bar-item {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
}

.status-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background-color: var(--clay-ochre);
  box-shadow: 0 0 0 2px rgba(196, 125, 59, 0.25);
}

.top-bar-bilingual {
  color: #d5cfc4;
  font-family: var(--font-sans);
  font-size: 0.76rem;
  letter-spacing: 0.03em;
}

/* ==========================================================================
   Site Header & Navigation
   ========================================================================== */

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--header-height);
  background-color: rgba(246, 242, 235, 0.93);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--rule-light);
  transition: box-shadow 0.25s ease, border-color 0.25s ease;
}

.site-header.is-scrolled {
  border-bottom-color: var(--rule-strong);
  box-shadow: var(--shadow-subtle);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.85rem;
  text-decoration: none;
  color: var(--ink-primary);
}

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

.brand-logo {
  width: 2.5rem;
  height: 2.5rem;
  border-radius: 8px;
  flex-shrink: 0;
}

.brand-text {
  display: flex;
  flex-direction: column;
  line-height: 1.15;
}

.brand-name {
  font-family: var(--font-serif);
  font-weight: 700;
  font-size: 1.2rem;
  letter-spacing: -0.015em;
  color: var(--ink-primary);
}

.brand-sub {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--ink-muted);
  letter-spacing: 0.03em;
  margin-top: 0.15rem;
}

.nav-list {
  display: flex;
  align-items: center;
  gap: 1.65rem;
  list-style: none;
}

.nav-link {
  position: relative;
  text-decoration: none;
  color: var(--ink-secondary);
  font-size: 0.92rem;
  font-weight: 500;
  padding: 0.35rem 0.15rem;
  transition: color 0.2s ease;
}

.nav-link::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: -2px;
  height: 1.5px;
  background-color: var(--clay-terracotta);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform 0.25s var(--ease-out-expo);
}

.nav-link:hover,
.nav-link.is-active {
  color: var(--ink-primary);
}

.nav-link:hover::after,
.nav-link.is-active::after {
  transform: scaleX(1);
}

.nav-link-cta {
  padding: 0.5rem 1.05rem;
  background-color: var(--lab-slate);
  color: var(--ink-on-dark) !important;
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: 0.82rem;
  font-weight: 600;
  letter-spacing: 0.03em;
}

.nav-link-cta::after {
  display: none;
}

.nav-link-cta:hover {
  background-color: var(--clay-terracotta);
  color: var(--ink-on-dark) !important;
}

/* Mobile Nav Toggle */
.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 5px;
  width: 2.5rem;
  height: 2.5rem;
  padding: 0.5rem;
  background: var(--bg-card);
  border: 1px solid var(--rule-strong);
  border-radius: var(--radius-sm);
  cursor: pointer;
}

.nav-toggle-bar {
  display: block;
  width: 18px;
  height: 1.75px;
  background-color: var(--ink-primary);
  transition: transform 0.2s ease, opacity 0.2s ease;
}

.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(1) {
  transform: translateY(6.75px) rotate(45deg);
}

.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(2) {
  opacity: 0;
}

.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(3) {
  transform: translateY(-6.75px) rotate(-45deg);
}

/* ==========================================================================
   Buttons
   ========================================================================== */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.6rem;
  padding: 0.825rem 1.45rem;
  font-size: 0.94rem;
  font-weight: 600;
  line-height: 1.25;
  text-decoration: none;
  border-radius: var(--radius-sm);
  border: 1px solid transparent;
  cursor: pointer;
  transition: background-color 0.2s ease, color 0.2s ease,
    border-color 0.2s ease, transform 0.2s ease;
}

.btn-icon {
  transition: transform 0.2s var(--ease-out-expo);
}

.btn:hover .btn-icon {
  transform: translateX(3px);
}

.btn-primary {
  background-color: var(--lab-slate);
  color: var(--ink-on-dark);
}

.btn-primary:hover {
  background-color: var(--clay-terracotta);
  color: var(--ink-on-dark);
}

.btn-secondary {
  background-color: var(--bg-card);
  color: var(--ink-primary);
  border-color: var(--rule-strong);
}

.btn-secondary:hover {
  background-color: var(--bg-alabaster);
  border-color: var(--ink-secondary);
  color: var(--ink-primary);
}

.btn-terracotta {
  background-color: var(--clay-terracotta);
  color: var(--ink-on-dark);
}

.btn-terracotta:hover {
  background-color: #c05836;
  color: var(--ink-on-dark);
}

.btn-large {
  padding: 0.95rem 1.75rem;
  font-size: 1rem;
  width: 100%;
}

/* ==========================================================================
   Hero Section
   ========================================================================== */

.hero {
  padding-block: 4.5rem 5.5rem;
  border-bottom: 1px solid var(--rule-strong);
  background: radial-gradient(
      circle at 85% 20%,
      rgba(196, 125, 59, 0.08),
      transparent 45%
    ),
    linear-gradient(180deg, var(--bg-alabaster) 0%, var(--bg-parchment) 100%);
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.08fr 0.92fr;
  gap: 3.5rem;
  align-items: center;
}

.eyebrow-group {
  display: inline-flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.65rem;
  margin-bottom: 1.35rem;
  padding: 0.35rem 0.8rem;
  background-color: var(--bg-card);
  border: 1px solid var(--rule-strong);
  border-left: 3px solid var(--clay-terracotta);
  border-radius: var(--radius-sm);
}

.eyebrow-code {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--clay-terracotta);
}

.eyebrow-zh {
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--wood-heartwood);
  padding-left: 0.65rem;
  border-left: 1px solid var(--rule-light);
}

.hero-title {
  font-family: var(--font-serif);
  font-size: clamp(2.15rem, 4vw, 3.25rem);
  font-weight: 700;
  line-height: 1.14;
  letter-spacing: -0.02em;
  color: var(--ink-primary);
  margin-bottom: 1.35rem;
}

.hero-lead {
  font-size: clamp(1.03rem, 1.4vw, 1.14rem);
  line-height: 1.72;
  color: var(--ink-secondary);
  margin-bottom: 2rem;
  max-width: 40rem;
}

.hero-lead strong {
  color: var(--ink-primary);
  font-weight: 600;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.9rem;
  margin-bottom: 2.5rem;
}

.hero-pillars {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1rem;
  padding-top: 1.75rem;
  border-top: 1px solid var(--rule-light);
}

.hero-pillar-card {
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
  padding: 1rem 1.15rem;
  background-color: var(--bg-card);
  border: 1px solid var(--rule-light);
  border-radius: var(--radius-sm);
  text-decoration: none;
  transition: border-color 0.2s ease, transform 0.2s ease,
    box-shadow 0.2s ease;
}

.hero-pillar-card:hover {
  border-color: var(--clay-terracotta);
  transform: translateY(-2px);
  box-shadow: var(--shadow-subtle);
}

.pillar-index {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--mineral-teal);
}

.pillar-title {
  font-family: var(--font-serif);
  font-size: 1rem;
  font-weight: 700;
  color: var(--ink-primary);
}

.pillar-zh {
  font-size: 0.8rem;
  color: var(--ink-muted);
  line-height: 1.45;
}

/* Hero Specimen Plate */
.specimen-plate {
  background-color: var(--lab-slate);
  color: var(--ink-on-dark);
  border: 1px solid var(--lab-slate-border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-dark);
  overflow: hidden;
}

.plate-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  padding: 0.75rem 1.15rem;
  background-color: var(--lab-slate-elevated);
  border-bottom: 1px solid var(--lab-slate-border);
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.06em;
  color: var(--ink-on-dark-muted);
}

.plate-scale {
  color: var(--mineral-teal-light);
}

.plate-canvas {
  position: relative;
  background-color: var(--lab-slate);
}

.hero-svg {
  width: 100%;
  height: auto;
}

.plate-caption {
  padding: 0.9rem 1.15rem;
  background-color: var(--lab-slate-elevated);
  border-top: 1px solid var(--lab-slate-border);
  font-size: 0.8rem;
  line-height: 1.55;
  color: var(--ink-on-dark-muted);
}

.plate-caption strong {
  color: var(--ink-on-dark);
}

/* ==========================================================================
   Generic Section & Editorial Grid Bars
   ========================================================================== */

.section {
  padding-block: 5.5rem;
  border-bottom: 1px solid var(--rule-light);
}

.section-alt {
  background-color: var(--bg-alabaster);
}

.section-meta-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.75rem;
  padding-bottom: 0.85rem;
  margin-bottom: 2.75rem;
  border-bottom: 1px solid var(--rule-strong);
}

.meta-index {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--clay-terracotta);
}

.meta-zh {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--wood-heartwood);
  letter-spacing: 0.04em;
}

.section-header {
  max-width: 46rem;
  margin-bottom: 3.25rem;
}

.section-title {
  font-family: var(--font-serif);
  font-size: clamp(1.75rem, 3vw, 2.45rem);
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: -0.015em;
  color: var(--ink-primary);
  margin-bottom: 1rem;
}

.section-subtitle {
  font-size: 1.06rem;
  line-height: 1.68;
  color: var(--ink-secondary);
}

/* Domain Pill */
.domain-pill {
  display: inline-flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 1rem;
  padding: 0.35rem 0.8rem;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  border-radius: var(--radius-sm);
}

.domain-pill-wood {
  background-color: var(--wood-soft);
  color: var(--wood-heartwood);
  border: 1px solid #d7c3b2;
}

.domain-pill-clay {
  background-color: var(--clay-terracotta-soft);
  color: var(--clay-terracotta-deep);
  border: 1px solid #e3bfb3;
}

.pill-divider {
  opacity: 0.55;
}

/* ==========================================================================
   About Section
   ========================================================================== */

.about-layout {
  display: grid;
  grid-template-columns: 0.9fr 1.1fr;
  gap: 4rem;
  align-items: start;
}

.about-header {
  position: sticky;
  top: calc(var(--header-height) + 2rem);
}

.about-tagline {
  font-size: 1.02rem;
  color: var(--wood-heartwood);
  font-weight: 500;
  margin-bottom: 1.75rem;
  line-height: 1.6;
}

.about-badge-box {
  background-color: var(--bg-card);
  border: 1px solid var(--rule-strong);
  border-radius: var(--radius-sm);
  padding: 1.15rem 1.25rem;
}

.badge-row {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 1rem;
  padding-block: 0.55rem;
  border-bottom: 1px solid var(--rule-light);
  font-size: 0.88rem;
}

.badge-row:first-child {
  padding-top: 0;
}

.badge-row:last-child {
  padding-bottom: 0;
  border-bottom: none;
}

.badge-label {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  font-weight: 600;
  color: var(--ink-muted);
  letter-spacing: 0.05em;
}

.badge-value {
  font-weight: 600;
  color: var(--ink-primary);
  text-align: right;
}

.prose p {
  font-size: 1.04rem;
  line-height: 1.75;
  color: var(--ink-secondary);
  margin-bottom: 1.25rem;
}

.prose p strong {
  color: var(--ink-primary);
  font-weight: 600;
}

.principles-grid {
  margin-top: 2.5rem;
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.15rem;
}

.principle-card {
  padding: 1.35rem 1.5rem;
  background-color: var(--bg-card);
  border: 1px solid var(--rule-light);
  border-left: 3px solid var(--wood-heartwood);
  border-radius: var(--radius-sm);
}

.principle-num {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--clay-terracotta);
  margin-bottom: 0.3rem;
}

.principle-title {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 0.5rem;
  font-family: var(--font-serif);
  font-size: 1.12rem;
  font-weight: 700;
  color: var(--ink-primary);
  margin-bottom: 0.45rem;
}

.title-zh {
  font-family: var(--font-sans);
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--wood-grain);
}

.principle-text {
  font-size: 0.94rem;
  color: var(--ink-secondary);
  line-height: 1.62;
}

/* ==========================================================================
   Research Directions / Services Section
   ========================================================================== */

.directions-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.5rem;
}

.direction-card {
  display: flex;
  flex-direction: column;
  padding: 2rem;
  background-color: var(--bg-card);
  border: 1px solid var(--rule-strong);
  border-radius: var(--radius-sm);
  transition: transform 0.25s var(--ease-out-expo),
    box-shadow 0.25s var(--ease-out-expo), border-color 0.2s ease;
}

.direction-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-elevated);
  border-color: var(--clay-terracotta);
}

.direction-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.5rem;
  padding-bottom: 0.85rem;
  margin-bottom: 1.25rem;
  border-bottom: 1px solid var(--rule-light);
}

.direction-code {
  font-family: var(--font-mono);
  font-size: 0.74rem;
  font-weight: 700;
  color: var(--mineral-teal);
  letter-spacing: 0.05em;
}

.direction-zh {
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--wood-heartwood);
}

.direction-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 3rem;
  height: 3rem;
  margin-bottom: 1.15rem;
  background-color: var(--bg-alabaster);
  color: var(--clay-terracotta);
  border: 1px solid var(--rule-light);
  border-radius: var(--radius-sm);
}

.direction-title {
  font-family: var(--font-serif);
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--ink-primary);
  margin-bottom: 0.65rem;
}

.direction-desc {
  font-size: 0.96rem;
  line-height: 1.65;
  color: var(--ink-secondary);
  margin-bottom: 1.5rem;
  flex-grow: 1;
}

.direction-tags {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  padding-top: 1.1rem;
  border-top: 1px solid var(--rule-light);
}

.direction-tags li {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--ink-secondary);
  background-color: var(--bg-parchment);
  padding: 0.25rem 0.6rem;
  border: 1px solid var(--rule-light);
  border-radius: 3px;
}

/* ==========================================================================
   Dedicated Section 1: Wooden Cultural Heritage Conservation & Restoration
   ========================================================================== */

.feature-intro {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  align-items: end;
  margin-bottom: 3rem;
}

.feature-intro-lead {
  font-size: 1.03rem;
  line-height: 1.72;
  color: var(--ink-secondary);
}

.wood-showcase-grid {
  display: grid;
  grid-template-columns: 1.05fr 0.95fr;
  gap: 2.5rem;
  align-items: start;
}

/* Dark Specimen Panel */
.wood-diagnostic-panel {
  position: sticky;
  top: calc(var(--header-height) + 1.5rem);
  background-color: var(--lab-slate);
  color: var(--ink-on-dark);
  border: 1px solid var(--lab-slate-border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-dark);
  overflow: hidden;
}

.diagnostic-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.75rem;
  padding: 1.15rem 1.35rem;
  background-color: var(--lab-slate-elevated);
  border-bottom: 1px solid var(--lab-slate-border);
}

.diagnostic-label {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--clay-ochre);
  letter-spacing: 0.06em;
  margin-bottom: 0.2rem;
}

.diagnostic-title {
  font-family: var(--font-serif);
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--ink-on-dark);
}

.diagnostic-zh {
  font-size: 0.78rem;
  color: var(--ink-on-dark-muted);
}

.lens-controls {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  background-color: #12171a;
  border-bottom: 1px solid var(--lab-slate-border);
}

.lens-btn {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 0.2rem;
  padding: 0.7rem 0.75rem;
  background: transparent;
  color: var(--ink-on-dark-muted);
  border: none;
  border-right: 1px solid var(--lab-slate-border);
  border-bottom: 2px solid transparent;
  font-family: var(--font-sans);
  font-size: 0.76rem;
  font-weight: 600;
  text-align: left;
  cursor: pointer;
  transition: background-color 0.2s ease, color 0.2s ease,
    border-color 0.2s ease;
}

.lens-btn:last-child {
  border-right: none;
}

.lens-btn:hover {
  background-color: rgba(255, 255, 255, 0.04);
  color: var(--ink-on-dark);
}

.lens-btn.is-active {
  background-color: var(--lab-slate-elevated);
  color: var(--ink-on-dark);
  border-bottom-color: var(--clay-ochre);
}

.lens-num {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  color: var(--mineral-teal-light);
}

.wood-svg {
  width: 100%;
  height: auto;
  border-bottom: 1px solid var(--lab-slate-border);
}

.wood-svg .diagram-group {
  transition: opacity 0.3s ease;
}

.wood-svg.has-active-lens .diagram-group {
  opacity: 0.32;
}

.wood-svg.has-active-lens .diagram-group.is-highlighted {
  opacity: 1;
}

.diagnostic-readout {
  padding: 1.15rem 1.35rem;
  background-color: var(--lab-slate-elevated);
}

.readout-badge {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  color: var(--mineral-teal-light);
  margin-bottom: 0.35rem;
}

.readout-text {
  font-size: 0.88rem;
  line-height: 1.58;
  color: var(--ink-on-dark-muted);
}

/* Right Column: 4 Wooden Heritage Pillars */
.wood-pillars-list {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.wood-pillar-item {
  padding: 1.6rem 1.75rem;
  background-color: var(--bg-card);
  border: 1px solid var(--rule-strong);
  border-left: 4px solid var(--wood-heartwood);
  border-radius: var(--radius-sm);
  transition: border-color 0.2s ease, background-color 0.2s ease,
    box-shadow 0.2s ease;
}

.wood-pillar-item:hover,
.wood-pillar-item.is-active {
  background-color: var(--bg-card-hover);
  border-left-color: var(--clay-terracotta);
  box-shadow: var(--shadow-subtle);
}

.wood-pillar-head {
  display: flex;
  align-items: baseline;
  gap: 1rem;
  margin-bottom: 0.75rem;
}

.wood-pillar-num {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--clay-terracotta);
  background-color: var(--clay-terracotta-soft);
  padding: 0.2rem 0.5rem;
  border-radius: 3px;
}

.wood-pillar-title {
  font-family: var(--font-serif);
  font-size: 1.22rem;
  font-weight: 700;
  color: var(--ink-primary);
}

.wood-pillar-zh {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--wood-grain);
  margin-top: 0.15rem;
}

.wood-pillar-body {
  font-size: 0.95rem;
  line-height: 1.68;
  color: var(--ink-secondary);
}

/* ==========================================================================
   Dedicated Section 2: Scientific Analysis of Pottery / Ceramics
   ========================================================================== */

.ceramics-layout {
  display: grid;
  grid-template-columns: 0.95fr 1.05fr;
  gap: 3.5rem;
  align-items: start;
}

.ceramics-lead {
  font-size: 1.02rem;
  line-height: 1.7;
  color: var(--ink-secondary);
  margin-bottom: 1.75rem;
}

.ceramic-schematic-card {
  background-color: var(--lab-slate);
  border: 1px solid var(--lab-slate-border);
  border-radius: var(--radius-md);
  overflow: hidden;
  box-shadow: var(--shadow-subtle);
}

.ceramic-svg {
  width: 100%;
  height: auto;
}

.ceramics-methods-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.25rem;
}

.method-card {
  padding: 1.5rem;
  background-color: var(--bg-card);
  border: 1px solid var(--rule-strong);
  border-top: 3px solid var(--clay-terracotta);
  border-radius: var(--radius-sm);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.method-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-subtle);
}

.method-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.5rem;
  margin-bottom: 0.65rem;
}

.method-abbr {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--clay-terracotta-deep);
  background-color: var(--clay-terracotta-soft);
  padding: 0.2rem 0.55rem;
  border-radius: 3px;
}

.method-zh {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--wood-heartwood);
}

.method-title {
  font-family: var(--font-serif);
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--ink-primary);
  margin-bottom: 0.5rem;
}

.method-desc {
  font-size: 0.91rem;
  line-height: 1.62;
  color: var(--ink-secondary);
}

/* ==========================================================================
   Approach (Method Workflow) Section
   ========================================================================== */

.workflow-grid {
  list-style: none;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1.25rem;
}

.workflow-step {
  display: flex;
  flex-direction: column;
  padding: 1.75rem 1.5rem;
  background-color: var(--bg-card);
  border: 1px solid var(--rule-strong);
  border-radius: var(--radius-sm);
  position: relative;
}

.workflow-step::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background-color: var(--mineral-teal);
}

.workflow-step-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.5rem;
  margin-bottom: 1rem;
}

.workflow-phase {
  font-family: var(--font-mono);
  font-size: 0.74rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--mineral-teal);
  background-color: var(--mineral-teal-soft);
  padding: 0.2rem 0.55rem;
  border-radius: 3px;
}

.workflow-zh {
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--wood-heartwood);
}

.workflow-title {
  font-family: var(--font-serif);
  font-size: 1.14rem;
  font-weight: 700;
  color: var(--ink-primary);
  margin-bottom: 0.65rem;
  line-height: 1.3;
}

.workflow-desc {
  font-size: 0.92rem;
  line-height: 1.62;
  color: var(--ink-secondary);
  margin-bottom: 1.25rem;
  flex-grow: 1;
}

.workflow-output {
  padding-top: 0.85rem;
  border-top: 1px dashed var(--rule-strong);
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--ink-muted);
}

/* ==========================================================================
   Contact Section
   ========================================================================== */

.section-contact {
  background-color: var(--bg-parchment);
  border-bottom: none;
}

.contact-panel {
  display: grid;
  grid-template-columns: 1.2fr 0.8fr;
  gap: 3rem;
  padding: 3.25rem;
  background-color: var(--lab-slate);
  color: var(--ink-on-dark);
  border: 1px solid var(--lab-slate-border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-dark);
}

.contact-meta-line {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.85rem;
  margin-bottom: 1rem;
}

.contact-code {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--clay-ochre);
}

.contact-zh {
  font-size: 0.82rem;
  color: var(--ink-on-dark-muted);
}

.contact-title {
  font-family: var(--font-serif);
  font-size: clamp(1.65rem, 2.8vw, 2.25rem);
  font-weight: 700;
  line-height: 1.2;
  color: var(--ink-on-dark);
  margin-bottom: 1rem;
}

.contact-description {
  font-size: 1rem;
  line-height: 1.68;
  color: var(--ink-on-dark-muted);
  margin-bottom: 1.75rem;
}

.contact-guidance {
  padding: 1.25rem 1.4rem;
  background-color: var(--lab-slate-elevated);
  border: 1px solid var(--lab-slate-border);
  border-left: 3px solid var(--mineral-teal-light);
  border-radius: var(--radius-sm);
}

.guidance-heading {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--ink-on-dark);
  margin-bottom: 0.65rem;
}

.guidance-list {
  padding-left: 1.15rem;
  font-size: 0.88rem;
  line-height: 1.6;
  color: var(--ink-on-dark-muted);
}

.guidance-list li + li {
  margin-top: 0.35rem;
}

.contact-box {
  padding: 2rem;
  background-color: var(--lab-slate-elevated);
  border: 1px solid var(--lab-slate-border);
  border-radius: var(--radius-sm);
  height: 100%;
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.contact-box-label {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.07em;
  color: var(--mineral-teal-light);
  margin-bottom: 0.75rem;
}

.contact-details {
  margin-top: 1.75rem;
  padding-top: 1.25rem;
  border-top: 1px solid var(--lab-slate-border);
}

.contact-detail-row {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  padding-block: 0.45rem;
  font-size: 0.86rem;
}

.contact-detail-row dt {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--ink-on-dark-muted);
}

.contact-detail-row dd {
  font-weight: 500;
  color: var(--ink-on-dark);
  text-align: right;
}

.contact-detail-row a {
  color: var(--clay-ochre);
}

.contact-detail-row a:hover {
  color: var(--ink-on-dark);
}

/* ==========================================================================
   Footer
   ========================================================================== */

.site-footer {
  padding-block: 3.5rem 2.5rem;
  background-color: var(--bg-alabaster);
  border-top: 1px solid var(--rule-strong);
  color: var(--ink-secondary);
  font-size: 0.9rem;
}

.footer-top {
  display: flex;
  justify-content: space-between;
  gap: 3rem;
  flex-wrap: wrap;
  padding-bottom: 2.25rem;
  border-bottom: 1px solid var(--rule-light);
}

.footer-brand-col {
  max-width: 28rem;
}

.footer-brand-link {
  margin-bottom: 0.75rem;
}

.brand-logo-sm {
  width: 2rem;
  height: 2rem;
  border-radius: 6px;
}

.footer-brand-name {
  font-family: var(--font-serif);
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--ink-primary);
}

.footer-tagline {
  font-size: 0.88rem;
  line-height: 1.6;
  color: var(--ink-muted);
}

.footer-nav {
  display: flex;
  gap: 3.5rem;
  flex-wrap: wrap;
}

.footer-nav-group {
  display: flex;
  flex-direction: column;
  gap: 0.45rem;
}

.footer-nav-title {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  color: var(--ink-primary);
  margin-bottom: 0.25rem;
}

.footer-nav-group a {
  color: var(--ink-secondary);
  text-decoration: none;
  font-size: 0.88rem;
}

.footer-nav-group a:hover {
  color: var(--clay-terracotta);
  text-decoration: underline;
}

.footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
  padding-top: 1.5rem;
  font-size: 0.84rem;
  color: var(--ink-muted);
}

.footer-copy a {
  color: var(--ink-secondary);
}

.footer-meta {
  font-family: var(--font-mono);
  font-size: 0.78rem;
}

/* ==========================================================================
   Scroll Reveal & Motion
   ========================================================================== */

.js-enabled .reveal {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 0.65s var(--ease-out-expo),
    transform 0.65s var(--ease-out-expo);
}

.js-enabled .reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
  .js-enabled .reveal {
    opacity: 1 !important;
    transform: none !important;
  }
}

/* ==========================================================================
   Responsive Breakpoints
   ========================================================================== */

@media (max-width: 1024px) {
  .hero-grid,
  .about-layout,
  .feature-intro,
  .wood-showcase-grid,
  .ceramics-layout,
  .contact-panel {
    grid-template-columns: 1fr;
    gap: 2.5rem;
  }

  .about-header,
  .wood-diagnostic-panel {
    position: static;
  }

  .workflow-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 768px) {
  .top-bar-bilingual {
    display: none;
  }

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

  .site-nav {
    display: none;
    position: absolute;
    top: var(--header-height);
    left: 0;
    right: 0;
    background-color: var(--bg-parchment);
    border-bottom: 1px solid var(--rule-strong);
    box-shadow: var(--shadow-elevated);
    padding: 1rem 1.5rem 1.5rem;
  }

  .site-nav.is-open {
    display: block;
  }

  .nav-list {
    flex-direction: column;
    align-items: stretch;
    gap: 0.35rem;
  }

  .nav-link {
    display: block;
    padding: 0.65rem 0.5rem;
  }

  .nav-link::after {
    display: none;
  }

  .nav-link-cta {
    text-align: center;
    margin-top: 0.35rem;
  }

  .hero {
    padding-block: 3rem 4rem;
  }

  .hero-pillars,
  .directions-grid,
  .ceramics-methods-grid,
  .workflow-grid {
    grid-template-columns: 1fr;
  }

  .lens-controls {
    grid-template-columns: repeat(2, 1fr);
  }

  .lens-btn:nth-child(2) {
    border-right: none;
  }

  .section {
    padding-block: 4rem;
  }

  .contact-panel {
    padding: 2rem 1.5rem;
  }
}