/* ==========================================================================
   LeinGPT - DeepSeek V4 & R1 Landing Page
   Concept 3: Song Dynasty Mathematical Treatise & Cinnabar Abacus Grid
   100% Light Mode: Warm Xuan Paper (#F6F2E9), Sumi Ink (#141413),
   Imperial Cinnabar (#C8281E), Celadon Jade (#2E6F5E)
   ========================================================================== */

:root {
  --ds-paper: #F6F2E9;
  --ds-paper-card: #FBF9F4;
  --ds-paper-deep: #ECE5D6;
  --ds-ink: #141413;
  --ds-ink-soft: #3B3935;
  --ds-muted: #6C6860;
  --ds-cinnabar: #C8281E;
  --ds-cinnabar-bg: #FCF0EE;
  --ds-celadon: #2E6F5E;
  --ds-celadon-bg: #EBF4F1;
  --ds-border: #141413;
  --ds-rule: #CFC7B6;
  --ds-font-sans: 'Space Grotesk', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --ds-font-serif: 'Cormorant Garamond', Georgia, serif;
  --ds-font-mono: 'IBM Plex Mono', ui-monospace, SFMono-Regular, Consolas, monospace;
}

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

html {
  scroll-behavior: smooth;
  background-color: var(--ds-paper);
  color: var(--ds-ink);
}

body.ds-body {
  margin: 0;
  font-family: var(--ds-font-sans);
  font-size: 16px;
  line-height: 1.58;
  background-color: var(--ds-paper);
  background-image:
    linear-gradient(to right, rgba(20, 20, 19, 0.035) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(20, 20, 19, 0.035) 1px, transparent 1px);
  background-size: 36px 36px;
  color: var(--ds-ink);
  overflow-x: hidden;
}

.ds-container {
  width: 100%;
  max-width: 1260px;
  margin: 0 auto;
  padding: 0 24px;
}

/* --------------------------------------------------------------------------
   Top Architectural Treatise Header
   -------------------------------------------------------------------------- */
.ds-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(246, 242, 233, 0.96);
  border-bottom: 3px double var(--ds-ink);
}

.ds-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  min-height: 68px;
  padding-top: 10px;
  padding-bottom: 10px;
  flex-wrap: wrap;
}

.ds-brand-wrap {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
}

.ds-brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: var(--ds-ink);
  font-family: var(--ds-font-mono);
  font-weight: 700;
  font-size: 0.9rem;
}

.ds-brand__seal {
  background: var(--ds-cinnabar);
  color: #FFFFFF;
  padding: 3px 8px;
  border: 2px solid var(--ds-cinnabar);
  font-weight: 700;
}

.ds-header__sub {
  font-size: 0.82rem;
  color: var(--ds-muted);
  border-inline-start: 1px solid var(--ds-rule);
  padding-inline-start: 10px;
}

.ds-nav {
  display: flex;
  align-items: center;
  gap: 18px;
  flex-wrap: wrap;
}

.ds-nav__link {
  color: var(--ds-ink);
  text-decoration: none;
  font-family: var(--ds-font-mono);
  font-size: 0.82rem;
  font-weight: 600;
  padding: 4px 6px;
  border-bottom: 2px solid transparent;
}

.ds-nav__link:hover {
  border-bottom-color: var(--ds-cinnabar);
  color: var(--ds-cinnabar);
}

.ds-actions {
  display: flex;
  align-items: center;
  gap: 12px;
}

/* Language Switcher */
.ds-lang {
  position: relative;
}

.ds-lang__btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: var(--ds-paper-card);
  color: var(--ds-ink);
  border: 1.5px solid var(--ds-ink);
  padding: 7px 11px;
  font-family: var(--ds-font-mono);
  font-size: 0.8rem;
  font-weight: 700;
  cursor: pointer;
}

.ds-lang__menu {
  position: absolute;
  inset-inline-end: 0;
  top: calc(100% + 6px);
  width: 220px;
  max-height: 320px;
  overflow-y: auto;
  background: var(--ds-paper-card);
  border: 2px solid var(--ds-ink);
  box-shadow: 6px 6px 0 rgba(20, 20, 19, 0.14);
  padding: 6px;
  z-index: 120;
}

.ds-lang__item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 7px 10px;
  color: var(--ds-ink);
  text-decoration: none;
  font-size: 0.83rem;
  border-bottom: 1px solid var(--ds-rule);
}

.ds-lang__item:hover,
.ds-lang__item.is-active {
  background: var(--ds-cinnabar);
  color: #FFFFFF;
  font-weight: 700;
}

/* Buttons */
.ds-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  font-family: var(--ds-font-mono);
  font-weight: 700;
  font-size: 0.86rem;
  text-transform: uppercase;
  text-decoration: none;
  padding: 10px 18px;
  border: 2px solid var(--ds-ink);
  cursor: pointer;
  transition: transform 0.12s ease, background-color 0.12s ease;
}

.ds-btn--cinnabar {
  background: var(--ds-cinnabar);
  color: #FFFFFF;
  border-color: var(--ds-cinnabar);
}

.ds-btn--cinnabar:hover {
  background: #A81F16;
  transform: translateY(-1px);
}

.ds-btn--ink {
  background: var(--ds-ink);
  color: var(--ds-paper);
}

.ds-btn--ink:hover {
  background: var(--ds-cinnabar);
  border-color: var(--ds-cinnabar);
  color: #FFFFFF;
}

.ds-btn--outline {
  background: var(--ds-paper-card);
  color: var(--ds-ink);
}

.ds-btn--outline:hover {
  background: var(--ds-paper-deep);
}

.ds-btn--lg {
  padding: 13px 22px;
  font-size: 0.94rem;
}

/* --------------------------------------------------------------------------
   Section 1: Hero Treatise Title Sheet & 4 Cinnabar Chop Seals
   -------------------------------------------------------------------------- */
.ds-hero {
  padding: 28px 0 54px;
  border-bottom: 2px solid var(--ds-ink);
}

.ds-crumbs {
  display: flex;
  align-items: center;
  gap: 8px;
  font-family: var(--ds-font-mono);
  font-size: 0.82rem;
  margin-bottom: 18px;
}

.ds-crumbs a {
  color: var(--ds-ink);
  font-weight: 700;
  text-decoration: underline;
}

.ds-hero__frame {
  background: var(--ds-paper-card);
  border: 2px solid var(--ds-ink);
  outline: 1px solid var(--ds-ink);
  outline-offset: -6px;
  padding: 32px;
}

.ds-hero__grid {
  display: grid;
  grid-template-columns: 1.3fr 1fr;
  gap: 34px;
  align-items: center;
}

.ds-celadon-pill {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  background: var(--ds-celadon);
  color: #FFFFFF;
  font-family: var(--ds-font-mono);
  font-size: 0.8rem;
  font-weight: 600;
  padding: 5px 12px;
  margin-bottom: 18px;
}

.ds-celadon-pill__code {
  background: rgba(0, 0, 0, 0.22);
  padding: 2px 6px;
}

.ds-hero__title {
  font-family: var(--ds-font-sans);
  font-weight: 700;
  font-size: clamp(2.1rem, 4vw, 3.45rem);
  line-height: 1.07;
  letter-spacing: -0.02em;
  text-transform: uppercase;
  margin: 0 0 18px;
}

.ds-hero__lead {
  font-size: 1.06rem;
  color: var(--ds-ink-soft);
  margin: 0 0 24px;
  max-width: 64ch;
}

.ds-hero__cta-row {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-bottom: 20px;
}

.ds-hero__notes {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  font-family: var(--ds-font-mono);
  font-size: 0.8rem;
  color: var(--ds-muted);
}

/* 4 Square Cinnabar Chop Seals */
.ds-seals-rack {
  background: var(--ds-paper);
  border: 1.5px solid var(--ds-ink);
  padding: 20px;
}

.ds-seals-rack__head {
  display: flex;
  justify-content: space-between;
  font-family: var(--ds-font-mono);
  font-size: 0.76rem;
  font-weight: 700;
  color: var(--ds-ink-soft);
  padding-bottom: 10px;
  margin-bottom: 16px;
  border-bottom: 1px solid var(--ds-ink);
}

.ds-chop-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 14px;
  margin-bottom: 14px;
}

.ds-chop {
  border: 3px solid var(--ds-cinnabar);
  outline: 1px solid var(--ds-cinnabar);
  outline-offset: -6px;
  background: var(--ds-cinnabar-bg);
  color: var(--ds-cinnabar);
  padding: 14px 12px;
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
}

.ds-chop--featured {
  background: var(--ds-cinnabar);
  color: #FFFFFF;
  outline-color: rgba(255, 255, 255, 0.65);
}

.ds-chop__corner {
  font-family: var(--ds-font-mono);
  font-size: 0.68rem;
  font-weight: 700;
  letter-spacing: 0.08em;
}

.ds-chop__price {
  font-family: var(--ds-font-sans);
  font-size: 1.85rem;
  line-height: 1.05;
  font-weight: 700;
}

.ds-chop__subprice {
  font-family: var(--ds-font-mono);
  font-size: 0.74rem;
  font-weight: 600;
}

.ds-chop__model {
  margin-top: 4px;
  font-family: var(--ds-font-mono);
  font-size: 0.82rem;
  font-weight: 700;
  padding: 2px 8px;
  border-top: 1px solid currentColor;
  border-bottom: 1px solid currentColor;
}

.ds-chop__desc {
  margin-top: 4px;
  font-size: 0.76rem;
  color: var(--ds-ink);
}

.ds-chop--featured .ds-chop__desc {
  color: #FFEAE8;
}

.ds-seals-rack__foot {
  margin: 0;
  font-size: 0.78rem;
  color: var(--ds-muted);
  text-align: center;
}

/* --------------------------------------------------------------------------
   Shared Section Headers
   -------------------------------------------------------------------------- */
.ds-section-head {
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  gap: 24px;
  flex-wrap: wrap;
  margin-bottom: 28px;
}

.ds-kicker {
  display: inline-block;
  font-family: var(--ds-font-mono);
  font-size: 0.78rem;
  font-weight: 700;
  color: var(--ds-cinnabar);
  border: 1.5px solid var(--ds-cinnabar);
  padding: 3px 10px;
  margin-bottom: 8px;
  text-transform: uppercase;
}

.ds-section-title {
  font-family: var(--ds-font-sans);
  font-size: clamp(1.75rem, 3vw, 2.5rem);
  line-height: 1.12;
  margin: 0;
}

.ds-section-sub {
  max-width: 52ch;
  margin: 0;
  font-size: 0.96rem;
  color: var(--ds-ink-soft);
}

/* --------------------------------------------------------------------------
   Section 2: Double-Page Treatise Spread (Proof Tree + Suanpan Abacus)
   -------------------------------------------------------------------------- */
.ds-spread-section {
  padding: 56px 0;
  border-bottom: 2px solid var(--ds-ink);
}

.ds-treatise-book {
  display: grid;
  grid-template-columns: 1fr 1fr;
  background: var(--ds-paper-card);
  border: 2px solid var(--ds-ink);
  box-shadow: 0 10px 0 rgba(20, 20, 19, 0.08);
}

.ds-folio {
  padding: 28px;
}

.ds-folio--left {
  border-inline-end: 2px solid var(--ds-ink);
  background-image: repeating-linear-gradient(
    to right,
    transparent,
    transparent 44px,
    rgba(20, 20, 19, 0.04) 44px,
    rgba(20, 20, 19, 0.04) 45px
  );
}

.ds-folio__header {
  border-bottom: 1.5px solid var(--ds-ink);
  padding-bottom: 12px;
  margin-bottom: 18px;
}

.ds-folio__num {
  display: block;
  font-family: var(--ds-font-mono);
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--ds-celadon);
  margin-bottom: 4px;
}

.ds-folio__title {
  margin: 0;
  font-size: 1.25rem;
}

.ds-proof-tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 18px;
}

.ds-proof-tab {
  font-family: var(--ds-font-mono);
  font-size: 0.78rem;
  font-weight: 600;
  background: var(--ds-paper);
  color: var(--ds-ink);
  border: 1.5px solid var(--ds-ink);
  padding: 7px 12px;
  cursor: pointer;
}

.ds-proof-tab.is-active,
.ds-proof-tab:hover {
  background: var(--ds-ink);
  color: var(--ds-paper);
}

/* Proof Tree Diagram */
.ds-tree-diagram {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.ds-tree-root,
.ds-tree-branch,
.ds-tree-conclusion {
  background: var(--ds-paper);
  border: 1.5px solid var(--ds-ink);
  padding: 14px 16px;
  position: relative;
}

.ds-tree-node__tag {
  display: inline-block;
  font-family: var(--ds-font-mono);
  font-size: 0.72rem;
  font-weight: 700;
  padding: 2px 7px;
  margin-bottom: 6px;
  background: var(--ds-ink);
  color: var(--ds-paper);
}

.ds-tree-branches {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
}

.ds-tree-branch--valid {
  border-color: var(--ds-celadon);
  background: var(--ds-celadon-bg);
}

.ds-tree-branch--valid .ds-tree-node__tag {
  background: var(--ds-celadon);
  color: #FFFFFF;
}

.ds-tree-branch--pruned {
  border-style: dashed;
  color: var(--ds-muted);
}

.ds-tree-branch--pruned .ds-tree-node__tag {
  background: var(--ds-cinnabar);
  color: #FFFFFF;
}

.ds-tree-conclusion {
  border: 2px solid var(--ds-cinnabar);
  background: var(--ds-cinnabar-bg);
}

.ds-tree-conclusion .ds-tree-node__tag {
  background: var(--ds-cinnabar);
  color: #FFFFFF;
}

.ds-tree-branch p,
.ds-tree-conclusion p {
  margin: 0;
  font-size: 0.9rem;
}

/* Right Folio: Suanpan Abacus Matrix */
.ds-abacus-intro {
  font-size: 0.9rem;
  color: var(--ds-ink-soft);
  margin: 0 0 16px;
}

.ds-abacus {
  border: 2px solid var(--ds-ink);
  background: var(--ds-paper);
  padding: 12px 16px;
  margin-bottom: 16px;
}

.ds-abacus__row {
  display: grid;
  grid-template-columns: 1.15fr 1.3fr auto;
  align-items: center;
  gap: 12px;
  padding: 10px 0;
  border-bottom: 1px solid var(--ds-rule);
}

.ds-abacus__row:last-child {
  border-bottom: none;
}

.ds-abacus__label strong {
  display: block;
  font-size: 0.92rem;
}

.ds-abacus__label span {
  font-size: 0.76rem;
  color: var(--ds-muted);
}

.ds-abacus__rod {
  position: relative;
  display: flex;
  align-items: center;
  gap: 6px;
  height: 24px;
  padding: 0 8px;
}

.ds-abacus__rod::before {
  content: '';
  position: absolute;
  inset-inline: 0;
  top: 50%;
  height: 2px;
  background: var(--ds-ink);
  z-index: 0;
}

.ds-bead {
  position: relative;
  z-index: 1;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  border: 1.5px solid var(--ds-ink);
  flex-shrink: 0;
}

.ds-bead--jade {
  background: var(--ds-celadon);
}

.ds-bead--cinnabar {
  background: var(--ds-cinnabar);
}

.ds-abacus__price {
  font-family: var(--ds-font-mono);
  font-weight: 700;
  font-size: 0.88rem;
  text-align: end;
}

.ds-abacus__row--expensive .ds-abacus__price {
  color: var(--ds-cinnabar);
}

.ds-abacus-summary {
  background: var(--ds-celadon-bg);
  border-inline-start: 4px solid var(--ds-celadon);
  padding: 12px 16px;
  font-size: 0.88rem;
}

.ds-abacus-summary p {
  margin: 4px 0 0;
  color: var(--ds-ink-soft);
}

/* --------------------------------------------------------------------------
   Section 3: 6 DeepSeek Models & Core Benefits
   -------------------------------------------------------------------------- */
.ds-models-section {
  padding: 56px 0;
  border-bottom: 2px solid var(--ds-ink);
}

.ds-models-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
  margin-bottom: 28px;
}

.ds-model-card {
  background: var(--ds-paper-card);
  border: 1.5px solid var(--ds-ink);
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.ds-model-card__top {
  display: flex;
  justify-content: space-between;
  font-family: var(--ds-font-mono);
  font-size: 0.74rem;
  color: var(--ds-muted);
  border-bottom: 1px solid var(--ds-rule);
  padding-bottom: 6px;
}

.ds-model-card__seal {
  color: var(--ds-cinnabar);
  font-weight: 700;
}

.ds-model-card__name {
  margin: 4px 0 0;
  font-size: 1.08rem;
}

.ds-model-card__price {
  font-family: var(--ds-font-mono);
  font-size: 1.55rem;
  font-weight: 700;
  color: var(--ds-cinnabar);
}

.ds-model-card__link {
  margin-top: auto;
  font-family: var(--ds-font-mono);
  font-size: 0.82rem;
  font-weight: 700;
  color: var(--ds-ink);
  text-decoration: underline;
}

.ds-benefits-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
}

.ds-benefit-card {
  background: var(--ds-paper-deep);
  border: 1.5px solid var(--ds-ink);
  padding: 20px;
}

.ds-benefit-card__num {
  display: inline-block;
  font-family: var(--ds-font-mono);
  font-size: 0.76rem;
  font-weight: 700;
  background: var(--ds-ink);
  color: var(--ds-paper);
  padding: 2px 8px;
  margin-bottom: 10px;
}

.ds-benefit-card__title {
  margin: 0 0 8px;
  font-size: 1.15rem;
}

.ds-benefit-card__desc {
  margin: 0;
  font-size: 0.92rem;
  color: var(--ds-ink-soft);
}

/* --------------------------------------------------------------------------
   Section 4: Two Architectural Pillars & Comparison Table
   -------------------------------------------------------------------------- */
.ds-pillars-section {
  padding: 56px 0;
  border-bottom: 2px solid var(--ds-ink);
}

.ds-pillars-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 28px;
  margin-bottom: 32px;
}

.ds-pillar {
  display: flex;
  flex-direction: column;
  background: var(--ds-paper-card);
  border: 2px solid var(--ds-ink);
}

.ds-pillar__entablature {
  padding: 20px 24px;
  border-bottom: 3px double var(--ds-ink);
  text-align: center;
  background: var(--ds-paper-deep);
}

.ds-pillar--leingpt .ds-pillar__entablature {
  background: var(--ds-cinnabar-bg);
  border-bottom-color: var(--ds-cinnabar);
}

.ds-pillar__tag {
  display: inline-block;
  font-family: var(--ds-font-mono);
  font-size: 0.74rem;
  font-weight: 700;
  margin-bottom: 4px;
}

.ds-pillar--leingpt .ds-pillar__tag {
  color: var(--ds-cinnabar);
}

.ds-pillar__title {
  margin: 0;
  font-size: 1.45rem;
}

.ds-pillar--leingpt .ds-pillar__title {
  color: var(--ds-cinnabar);
}

.ds-pillar__shaft {
  padding: 20px 28px;
  flex: 1;
}

.ds-pillar__rows {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.ds-pillar__rows li {
  padding-bottom: 12px;
  border-bottom: 1px dashed var(--ds-rule);
}

.ds-pillar__rows li:last-child {
  border-bottom: none;
  padding-bottom: 0;
}

.ds-pillar__rows strong {
  display: block;
  font-size: 0.98rem;
  margin-bottom: 2px;
}

.ds-pillar__rows span {
  font-size: 0.88rem;
  color: var(--ds-ink-soft);
}

.ds-pillar__plinth {
  padding: 10px 18px;
  background: var(--ds-ink);
  color: var(--ds-paper);
  font-family: var(--ds-font-mono);
  font-size: 0.76rem;
  font-weight: 700;
  text-align: center;
}

.ds-pillar--leingpt .ds-pillar__plinth {
  background: var(--ds-celadon);
  color: #FFFFFF;
}

/* Comparison Table */
.ds-table-wrap {
  overflow-x: auto;
  border: 2px solid var(--ds-ink);
  background: var(--ds-paper-card);
  margin-bottom: 28px;
}

.ds-table {
  width: 100%;
  border-collapse: collapse;
  text-align: start;
}

.ds-table th,
.ds-table td {
  padding: 13px 16px;
  border: 1px solid var(--ds-ink);
  font-size: 0.93rem;
}

.ds-table thead th {
  background: var(--ds-ink);
  color: var(--ds-paper);
  font-family: var(--ds-font-mono);
  font-size: 0.82rem;
  text-transform: uppercase;
}

.ds-table thead th.is-ours {
  background: var(--ds-cinnabar);
  color: #FFFFFF;
}

.ds-table tbody td.is-ours {
  background: var(--ds-celadon-bg);
  font-weight: 600;
}

.ds-steps-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
}

.ds-step-card {
  background: var(--ds-paper-card);
  border: 1.5px solid var(--ds-ink);
  padding: 18px 20px;
}

.ds-step-card__num {
  display: inline-block;
  font-family: var(--ds-font-mono);
  font-size: 0.76rem;
  font-weight: 700;
  color: var(--ds-cinnabar);
  margin-bottom: 6px;
}

.ds-step-card__text {
  margin: 0;
  font-size: 0.93rem;
}

/* --------------------------------------------------------------------------
   Section 5: FAQ & Related Bar
   -------------------------------------------------------------------------- */
.ds-faq-section {
  padding: 56px 0;
}

.ds-faq-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
  margin-bottom: 28px;
}

.ds-faq-item {
  background: var(--ds-paper-card);
  border: 1.5px solid var(--ds-ink);
  padding: 14px 18px;
}

.ds-faq-item__q {
  cursor: pointer;
  font-weight: 700;
  display: flex;
  align-items: center;
  gap: 10px;
  list-style: none;
}

.ds-faq-item__q::-webkit-details-marker {
  display: none;
}

.ds-faq-item__seal {
  font-family: var(--ds-font-mono);
  font-size: 0.74rem;
  background: var(--ds-cinnabar);
  color: #FFFFFF;
  padding: 2px 7px;
  flex-shrink: 0;
}

.ds-faq-item__a {
  margin-top: 10px;
  padding-top: 10px;
  border-top: 1px dashed var(--ds-rule);
  font-size: 0.92rem;
  color: var(--ds-ink-soft);
}

.ds-faq-item__a p {
  margin: 0;
}

.ds-related-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 14px;
  background: var(--ds-paper-deep);
  border: 1.5px solid var(--ds-ink);
  padding: 16px 20px;
}

.ds-related-bar__label {
  font-family: var(--ds-font-mono);
  font-size: 0.86rem;
  font-weight: 700;
}

.ds-related-bar__links {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.ds-related-link {
  font-family: var(--ds-font-mono);
  font-size: 0.82rem;
  font-weight: 700;
  color: var(--ds-ink);
  background: var(--ds-paper-card);
  border: 1.5px solid var(--ds-ink);
  padding: 6px 12px;
  text-decoration: none;
}

.ds-related-link:hover {
  background: var(--ds-cinnabar);
  color: #FFFFFF;
  border-color: var(--ds-cinnabar);
}

/* --------------------------------------------------------------------------
   Footer
   -------------------------------------------------------------------------- */
.ds-footer {
  background: var(--ds-ink);
  color: var(--ds-paper);
  border-top: 3px solid var(--ds-cinnabar);
  padding: 32px 0;
}

.ds-footer__inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 20px;
}

.ds-footer__cta {
  display: block;
  font-size: 1.15rem;
  margin-bottom: 4px;
}

.ds-footer__copy {
  margin: 0;
  font-size: 0.84rem;
  color: #B9B3A6;
}

.ds-footer__right {
  display: flex;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
}

.ds-footer__link {
  color: var(--ds-paper);
  font-family: var(--ds-font-mono);
  font-size: 0.84rem;
  text-decoration: underline;
}

/* --------------------------------------------------------------------------
   Responsive Breakpoints
   -------------------------------------------------------------------------- */
@media (max-width: 1024px) {
  .ds-hero__grid,
  .ds-treatise-book,
  .ds-pillars-grid {
    grid-template-columns: 1fr;
  }

  .ds-folio--left {
    border-inline-end: none;
    border-bottom: 2px solid var(--ds-ink);
  }

  .ds-models-grid,
  .ds-benefits-grid,
  .ds-steps-grid,
  .ds-faq-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 640px) {
  .ds-chop-grid,
  .ds-tree-branches,
  .ds-abacus__row {
    grid-template-columns: 1fr;
  }

  .ds-hero__frame {
    padding: 20px 16px;
  }
}