/**
 * GoxEDGE design v4 — editorial companion site.
 * Namespace: v4-
 */

:root {
  --v4-bg: #f6f0e4;
  --v4-paper: #fffaf0;
  --v4-white: #ffffff;
  --v4-ink: #17202a;
  --v4-muted: #5f6975;
  --v4-soft: #8b929c;
  --v4-line: rgba(23, 32, 42, 0.12);

  --v4-navy: #062f4f;
  --v4-blue: #075aa8;
  --v4-teal: #0f6674;
  --v4-bronze: #a9793e;
  --v4-red: #f04a23;
  --v4-green: #2f7d32;
  --v4-purple: #4b2ca3;
  --v4-sky: #1288c7;
  --v4-sustain: #1f6b2c;

  --v4-radius-sm: 10px;
  --v4-radius-md: 16px;
  --v4-radius-lg: 24px;
  --v4-radius-xl: 32px;

  --v4-shadow-soft: 0 14px 36px rgba(23, 32, 42, 0.08);
  --v4-shadow-book: 0 28px 70px rgba(23, 32, 42, 0.18);

  --v4-container: 1180px;
  --v4-wide: 1320px;

  --v4-font-sans: Inter, -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  --v4-font-serif: "Noto Serif SC", "Songti SC", SimSun, Georgia, serif;

  --v4-section-y: 88px;
  --v4-section-compact: 64px;
  --v4-section-mobile: 48px;
}

body.v4-site {
  font-family: var(--v4-font-sans);
  color: var(--v4-ink);
  background: var(--v4-bg);
  line-height: 1.85;
  margin: 0;
}

/* Containers */
.v4-container {
  max-width: var(--v4-container);
  margin: 0 auto;
  padding: 0 32px;
}

.v4-wide {
  max-width: var(--v4-wide);
  margin: 0 auto;
  padding: 0 32px;
}

.v4-prose h2 {
  font-family: var(--v4-font-serif);
  font-size: 1.5rem;
  margin: 0 0 14px;
  color: var(--v4-ink);
}

.v4-prose p {
  margin: 0 0 18px;
  color: var(--v4-muted);
}

/* Section rhythm */
.v4-site main > section {
  padding: var(--v4-section-y) 0;
}

.v4-site main > section.v4-thesis,
.v4-site main > section.v4-hero {
  padding-top: 0;
  padding-bottom: 0;
}

.v4-site main > section.v4-page-hero {
  padding-top: 72px;
  padding-bottom: var(--v4-section-compact);
}

/* Backgrounds */
.v4-bg-hero-book {
  position: relative;
  background: linear-gradient(180deg, var(--v4-paper) 0%, var(--v4-bg) 100%);
}

.v4-bg-hero-book::before {
  content: "";
  position: absolute;
  inset: 0;
  background: url("../img/backgrounds/v4-bg-hero-book.svg") center top / cover no-repeat;
  opacity: 0.32;
  pointer-events: none;
}

.v4-bg-model-grid {
  position: relative;
}

.v4-bg-model-grid::before {
  content: "";
  position: absolute;
  inset: 0;
  background: url("../img/backgrounds/v4-bg-model-grid.svg") center / cover no-repeat;
  opacity: 0.26;
  pointer-events: none;
}

.v4-bg-resource-index {
  position: relative;
}

.v4-bg-resource-index::before {
  content: "";
  position: absolute;
  inset: 0;
  background: url("../img/backgrounds/v4-bg-resource-index.svg") right top / 50% auto no-repeat;
  opacity: 0.22;
  pointer-events: none;
}

.v4-bg-hero-book > .v4-container,
.v4-bg-hero-book > .v4-wide,
.v4-bg-model-grid > .v4-container,
.v4-bg-model-grid > .v4-wide,
.v4-bg-resource-index > .v4-container,
.v4-bg-resource-index > .v4-wide {
  position: relative;
  z-index: 1;
}

/* Header */
.v4-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 250, 240, 0.96);
  border-bottom: 1px solid var(--v4-line);
  backdrop-filter: blur(8px);
}

.v4-header-inner {
  min-height: 76px;
  display: flex;
  align-items: center;
  gap: 24px;
}

.v4-brand {
  display: flex;
  flex-direction: column;
  flex-shrink: 0;
  text-decoration: none;
  color: var(--v4-ink);
}

.v4-brand-name {
  font-size: 1.125rem;
  font-weight: 700;
  letter-spacing: 0.02em;
}

.v4-brand-sub {
  font-size: 0.625rem;
  color: var(--v4-soft);
  letter-spacing: 0.1em;
}

.v4-nav.nav-menu {
  display: flex;
  flex: 1;
  justify-content: center;
  gap: 2px;
}

.v4-nav .nav-link {
  font-size: 0.875rem;
  color: var(--v4-muted);
  padding: 8px 14px;
  border-radius: 6px;
  text-decoration: none;
}

.v4-nav .nav-link:hover,
.v4-nav .nav-link.active {
  color: var(--v4-ink);
  background: rgba(23, 32, 42, 0.04);
}

.v4-nav .nav-link.active {
  font-weight: 600;
}

.v4-header-cta {
  flex-shrink: 0;
}

.v4-menu-toggle {
  display: none;
  border: 1px solid var(--v4-line);
  background: var(--v4-paper);
  border-radius: 6px;
  padding: 8px 12px;
  font-size: 0.875rem;
  font-weight: 600;
  cursor: pointer;
  margin-left: auto;
}

/* Buttons */
.v4-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 12px 24px;
  font-size: 0.875rem;
  font-weight: 600;
  border-radius: 8px;
  border: 1px solid transparent;
  cursor: pointer;
  text-decoration: none;
  white-space: nowrap;
  font-family: inherit;
}

.v4-btn-primary {
  background: var(--v4-navy);
  color: #fff;
  border-color: var(--v4-navy);
}

.v4-btn-primary:hover {
  background: #041f35;
}

.v4-btn-secondary {
  background: transparent;
  color: var(--v4-ink);
  border-color: rgba(23, 32, 42, 0.2);
}

.v4-btn-secondary:hover {
  background: rgba(23, 32, 42, 0.04);
}

.v4-text-link {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--v4-navy);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.v4-section-cta {
  margin-top: 36px;
}

/* Hero */
.v4-hero {
  padding-top: 72px;
  padding-bottom: var(--v4-section-y);
}

.v4-hero-grid {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  gap: 72px;
  align-items: center;
}

.v4-hero-copy {
  grid-column: span 7;
}

.v4-hero-visual {
  grid-column: span 5;
  display: flex;
  justify-content: center;
}

.v4-hero-label {
  font-size: 0.75rem;
  letter-spacing: 0.12em;
  color: var(--v4-soft);
  margin: 0 0 20px;
}

.v4-hero-title {
  font-family: var(--v4-font-serif);
  font-size: clamp(52px, 7vw, 84px);
  line-height: 1.05;
  letter-spacing: -0.04em;
  font-weight: 600;
  margin: 0;
}

.v4-hero-subtitle {
  font-family: var(--v4-font-serif);
  font-size: clamp(1.25rem, 2.5vw, 1.75rem);
  color: var(--v4-muted);
  margin: 16px 0 20px;
}

.v4-hero-model {
  font-size: 1rem;
  font-weight: 600;
  color: var(--v4-navy);
  margin: 0 0 8px;
}

.v4-hero-support {
  font-size: 0.875rem;
  color: var(--v4-soft);
  margin: 0 0 28px;
}

.v4-hero-thesis {
  margin: 0 0 24px;
  padding-left: 20px;
  border-left: 3px solid var(--v4-bronze);
  font-family: var(--v4-font-serif);
  font-size: 1.25rem;
  font-weight: 600;
  line-height: 1.5;
}

.v4-hero-body {
  font-size: 1.0625rem;
  color: var(--v4-muted);
  max-width: 640px;
  margin: 0 0 32px;
  line-height: 1.85;
}

.v4-hero-actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 16px;
  margin-bottom: 12px;
}

.v4-hero-note {
  margin: 0;
  font-size: 0.75rem;
  color: var(--v4-soft);
}

/* Book mockup */
.v4-book-cover {
  width: min(100%, 360px);
  aspect-ratio: 0.68;
  position: relative;
  background: linear-gradient(168deg, #fffaf0 0%, #f0e8da 100%);
  border: 1px solid var(--v4-line);
  border-radius: 4px 14px 14px 4px;
  box-shadow: var(--v4-shadow-book);
}

.v4-book-cover::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 20px;
  background: linear-gradient(90deg, #d4cbb8 0%, #ebe3d4 55%, transparent 100%);
  border-radius: 4px 0 0 4px;
}

.v4-book-cover-face {
  position: relative;
  height: 100%;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  padding: 44px 36px 40px 44px;
  z-index: 1;
}

.v4-book-cover-publisher {
  font-size: 0.625rem;
  letter-spacing: 0.16em;
  color: var(--v4-soft);
}

.v4-book-cover-title {
  font-family: var(--v4-font-serif);
  font-size: 2.75rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  margin: 40px 0 10px;
  line-height: 1.1;
}

.v4-book-cover-subtitle {
  font-family: var(--v4-font-serif);
  font-size: 1rem;
  color: var(--v4-muted);
  margin: 0;
}

.v4-book-cover-model {
  font-size: 0.7rem;
  color: var(--v4-navy);
  font-weight: 600;
  margin-top: 28px;
  padding-top: 20px;
  border-top: 1px solid var(--v4-line);
}

.v4-book-cover-author {
  font-size: 0.875rem;
  color: var(--v4-muted);
  margin: 0;
}

/* Thesis band */
.v4-thesis {
  padding: 64px 0;
  background: var(--v4-navy);
  color: #f8f5ef;
}

.v4-thesis-inner {
  max-width: 760px;
  margin: 0 auto;
  text-align: center;
  border-top: 1px solid rgba(169, 121, 62, 0.5);
  border-bottom: 1px solid rgba(169, 121, 62, 0.5);
  padding: 40px 28px;
}

.v4-thesis h2 {
  font-family: var(--v4-font-serif);
  font-size: clamp(1.35rem, 3vw, 1.9rem);
  margin: 0 0 20px;
  font-weight: 600;
  line-height: 1.35;
}

.v4-thesis p {
  margin: 0;
  color: rgba(248, 245, 239, 0.88);
  line-height: 1.85;
  max-width: 680px;
  margin-inline: auto;
}

/* Section heads */
.v4-section-head {
  max-width: 760px;
  margin-bottom: 40px;
}

.v4-section-head--wide {
  max-width: 820px;
}

.v4-section-head h2 {
  font-family: var(--v4-font-serif);
  font-size: clamp(34px, 4vw, 48px);
  line-height: 1.18;
  margin: 0 0 16px;
  font-weight: 600;
}

.v4-section-intro {
  margin: 0;
  font-size: 1rem;
  color: var(--v4-muted);
  line-height: 1.85;
  max-width: 760px;
}

/* Problems */
.v4-problems {
  background: var(--v4-paper);
}

.v4-problem-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
}

.v4-problem-card {
  padding: 32px 28px;
  background: var(--v4-white);
  border: 1px solid var(--v4-line);
  border-radius: var(--v4-radius-sm);
}

.v4-problem-card h3 {
  font-family: var(--v4-font-serif);
  font-size: 1.125rem;
  margin: 0 0 12px;
}

.v4-problem-card p {
  margin: 0;
  font-size: 0.9375rem;
  color: var(--v4-muted);
  line-height: 1.85;
}

/* Home model */
.v4-home-model-layout {
  display: grid;
  grid-template-columns: 1.15fr 0.85fr;
  gap: 48px;
  align-items: start;
}

.v4-model-mini {
  border: 1px solid var(--v4-line);
  border-radius: var(--v4-radius-sm);
  background: var(--v4-white);
  overflow: hidden;
}

.v4-model-mini-row {
  display: grid;
  grid-template-columns: 9.5rem 1fr;
  gap: 16px;
  padding: 18px 22px;
  border-bottom: 1px solid var(--v4-line);
  align-items: center;
}

.v4-model-mini-row:last-child {
  border-bottom: 0;
}

.v4-model-mini-row span {
  font-size: 0.75rem;
  font-weight: 700;
}

.v4-model-mini-row em {
  font-style: normal;
  font-size: 0.875rem;
  color: var(--v4-muted);
}

.v4-model-mini-row--mech { border-left: 3px solid var(--v4-red); }
.v4-model-mini-row--path { border-left: 3px solid var(--v4-navy); }
.v4-model-mini-row--edge { border-left: 3px solid var(--v4-teal); }
.v4-model-mini-row--judge { border-left: 3px solid var(--v4-green); }

.v4-home-model-aside {
  padding: 32px 28px;
  background: var(--v4-white);
  border: 1px solid var(--v4-line);
  border-radius: var(--v4-radius-sm);
}

.v4-home-model-aside p {
  margin: 0 0 28px;
  font-size: 0.9375rem;
  color: var(--v4-muted);
  line-height: 1.85;
}

/* Resources */
.v4-resource-preview {
  background: var(--v4-paper);
}

.v4-resource-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.v4-resource-card {
  padding: 22px;
  background: var(--v4-white);
  border: 1px solid var(--v4-line);
  border-radius: var(--v4-radius-sm);
}

.v4-resource-card-cat {
  font-size: 0.6875rem;
  font-weight: 600;
  color: var(--v4-soft);
  letter-spacing: 0.08em;
  margin: 0 0 6px;
  text-transform: uppercase;
}

.v4-resource-card h3 {
  font-size: 0.9375rem;
  margin: 0 0 6px;
  font-weight: 600;
  line-height: 1.4;
}

.v4-resource-card p {
  margin: 0 0 12px;
  font-size: 0.8125rem;
  color: var(--v4-muted);
  line-height: 1.7;
}

.v4-status-badge {
  display: inline-block;
  font-size: 0.6875rem;
  font-weight: 600;
  padding: 4px 10px;
  border-radius: 4px;
  background: rgba(23, 32, 42, 0.06);
  color: var(--v4-muted);
}

.v4-status-badge--soon {
  background: rgba(6, 47, 79, 0.08);
  color: var(--v4-navy);
}

.v4-status-badge--book {
  background: rgba(169, 121, 62, 0.12);
  color: #7a5a28;
}

/* Reading table */
.v4-reading-table {
  width: 100%;
  border-collapse: collapse;
  background: var(--v4-white);
  border: 1px solid var(--v4-line);
  border-radius: var(--v4-radius-sm);
  overflow: hidden;
  font-size: 0.9375rem;
}

.v4-reading-table th,
.v4-reading-table td {
  padding: 16px 20px;
  text-align: left;
  border-bottom: 1px solid var(--v4-line);
  vertical-align: top;
  line-height: 1.75;
}

.v4-reading-table th {
  background: var(--v4-bg);
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--v4-muted);
}

.v4-reading-table tbody tr:last-child td {
  border-bottom: 0;
}

.v4-reading-table td:nth-child(2) {
  color: var(--v4-navy);
  font-weight: 600;
  white-space: nowrap;
}

/* Minvista */
.v4-minvista-card {
  display: grid;
  grid-template-columns: 1fr 200px;
  gap: 56px;
  align-items: start;
  padding: 44px 48px;
  background: var(--v4-white);
  border: 1px solid var(--v4-line);
  border-radius: var(--v4-radius-md);
  box-shadow: var(--v4-shadow-soft);
}

.v4-minvista-label {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--v4-soft);
  letter-spacing: 0.08em;
  margin: 0 0 10px;
}

.v4-minvista-card h2 {
  font-family: var(--v4-font-serif);
  font-size: 1.625rem;
  margin: 0 0 16px;
  line-height: 1.25;
}

.v4-minvista-body {
  margin: 0 0 14px;
  color: var(--v4-muted);
  max-width: 640px;
  line-height: 1.85;
  font-size: 0.9375rem;
}

.v4-minvista-tagline {
  margin: 0 0 8px;
  font-size: 0.875rem;
  font-weight: 600;
}

.v4-minvista-keyword {
  margin: 0;
  font-size: 0.875rem;
  color: var(--v4-muted);
}

.v4-minvista-side {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 18px;
}

.v4-minvista-qr {
  width: 180px;
  height: 180px;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--v4-line);
  border-radius: var(--v4-radius-sm);
  background: var(--v4-bg);
  font-size: 0.8125rem;
  color: var(--v4-soft);
  text-align: center;
  padding: 16px;
}

/* Final contact */
.v4-final-contact {
  background: var(--v4-bg);
  border-top: 1px solid var(--v4-line);
}

.v4-final-contact-inner {
  max-width: 760px;
}

.v4-final-contact h2 {
  font-family: var(--v4-font-serif);
  font-size: clamp(1.5rem, 3vw, 2rem);
  margin: 0 0 14px;
}

.v4-final-contact p {
  margin: 0 0 28px;
  color: var(--v4-muted);
  line-height: 1.85;
  max-width: 760px;
}

/* Page hero */
.v4-page-hero h1 {
  font-family: var(--v4-font-serif);
  font-size: clamp(2rem, 4vw, 2.75rem);
  margin: 8px 0 14px;
  line-height: 1.15;
}

.v4-page-kicker {
  font-size: 0.8125rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  color: var(--v4-bronze);
  margin: 0 0 6px;
}

.v4-page-lead {
  font-size: 1.0625rem;
  color: var(--v4-muted);
  margin: 0;
  max-width: 760px;
  line-height: 1.85;
}

.v4-page-note {
  font-size: 0.9375rem;
  color: var(--v4-muted);
  margin: 12px 0 0;
  max-width: 760px;
  line-height: 1.85;
}

.v4-breadcrumb {
  font-size: 0.8125rem;
  color: var(--v4-soft);
  margin-bottom: 8px;
}

.v4-breadcrumb a {
  color: var(--v4-muted);
  text-decoration: none;
}

/* Footer */
.v4-footer {
  background: #0d1a26;
  color: rgba(248, 245, 239, 0.78);
  padding: 64px 0 32px;
}

.v4-footer-grid {
  display: grid;
  grid-template-columns: 1.4fr repeat(4, 1fr);
  gap: 32px;
  margin-bottom: 40px;
}

.v4-footer-brand p {
  margin: 14px 0 0;
  font-size: 0.875rem;
  line-height: 1.75;
  max-width: 320px;
}

.v4-footer-note {
  margin-top: 10px !important;
  font-size: 0.8125rem !important;
  color: rgba(248, 245, 239, 0.55) !important;
}

.v4-footer-col h4 {
  font-size: 0.8125rem;
  color: #f8f5ef;
  margin: 0 0 14px;
}

.v4-footer-col a {
  display: block;
  font-size: 0.875rem;
  color: rgba(248, 245, 239, 0.72);
  text-decoration: none;
  margin-bottom: 8px;
}

.v4-footer-col a:hover {
  color: #fff;
}

.v4-footer-bottom {
  padding-top: 24px;
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  font-size: 0.75rem;
  color: rgba(248, 245, 239, 0.5);
}

/* Interior */
.v4-grid-2 {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 28px;
}

.v4-book-intro {
  display: grid;
  grid-template-columns: 1fr 340px;
  gap: 48px;
  align-items: start;
}

.v4-book-meta {
  margin: 20px 0 0;
  padding: 0;
  list-style: none;
}

.v4-book-meta li {
  display: grid;
  grid-template-columns: 5rem 1fr;
  gap: 12px;
  padding: 10px 0;
  border-bottom: 1px solid var(--v4-line);
  font-size: 0.875rem;
}

.v4-book-meta li:last-child {
  border-bottom: 0;
}

.v4-book-meta dt {
  margin: 0;
  color: var(--v4-soft);
  font-weight: 500;
}

.v4-book-meta dd {
  margin: 0;
  color: var(--v4-ink);
}

.v4-audience-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
}

.v4-audience-card {
  padding: 20px 22px;
  background: var(--v4-white);
  border: 1px solid var(--v4-line);
  border-radius: var(--v4-radius-sm);
}

.v4-audience-card h3 {
  font-size: 0.9375rem;
  margin: 0 0 6px;
}

.v4-audience-card p {
  margin: 0;
  font-size: 0.8125rem;
  color: var(--v4-muted);
  line-height: 1.7;
}

.v4-purchase-note {
  padding: 16px 20px;
  background: var(--v4-bg);
  border: 1px solid var(--v4-line);
  border-radius: var(--v4-radius-sm);
  font-size: 0.875rem;
  color: var(--v4-muted);
  max-width: 760px;
}

.v4-status-legend {
  display: flex;
  flex-wrap: wrap;
  gap: 16px 24px;
  margin-bottom: 28px;
  padding: 14px 18px;
  background: var(--v4-white);
  border: 1px solid var(--v4-line);
  border-radius: var(--v4-radius-sm);
  font-size: 0.8125rem;
  color: var(--v4-muted);
}

.v4-notice {
  padding: 18px 22px;
  background: var(--v4-bg);
  border: 1px solid var(--v4-line);
  border-radius: var(--v4-radius-sm);
  font-size: 0.875rem;
  color: var(--v4-muted);
  line-height: 1.75;
  max-width: 760px;
}

.v4-notice--spaced {
  margin-top: 28px;
}

.v4-toc-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 20px;
}

.v4-toc-part {
  padding: 20px 22px;
  background: var(--v4-white);
  border: 1px solid var(--v4-line);
  border-radius: var(--v4-radius-sm);
}

.v4-toc-part h3 {
  font-size: 0.9375rem;
  margin: 0 0 10px;
}

.v4-toc-list {
  margin: 0;
  padding-left: 1.1em;
  font-size: 0.8125rem;
  color: var(--v4-muted);
  line-height: 1.7;
}

.v4-role-list {
  border: 1px solid var(--v4-line);
  border-radius: var(--v4-radius-sm);
  background: var(--v4-white);
  overflow: hidden;
}

.v4-role-item {
  padding: 18px 22px;
  border-bottom: 1px solid var(--v4-line);
}

.v4-role-item:last-child {
  border-bottom: 0;
}

.v4-role-item h3 {
  font-size: 0.9375rem;
  margin: 0 0 4px;
}

.v4-role-item p {
  margin: 0;
  font-size: 0.8125rem;
  color: var(--v4-muted);
  line-height: 1.7;
}

.v4-role-chapters {
  display: inline-block;
  margin-top: 6px;
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--v4-navy);
}

.v4-update-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 20px;
}

.v4-update-item {
  padding: 22px;
  background: var(--v4-white);
  border: 1px solid var(--v4-line);
  border-radius: var(--v4-radius-sm);
}

.v4-update-item h3 {
  font-size: 0.9375rem;
  margin: 0 0 6px;
}

.v4-update-item p {
  margin: 0;
  font-size: 0.8125rem;
  color: var(--v4-muted);
  line-height: 1.7;
}

.v4-contact-block {
  max-width: 760px;
  margin-bottom: 36px;
}

.v4-contact-block:last-child {
  margin-bottom: 0;
}

.v4-contact-block h2 {
  font-family: var(--v4-font-serif);
  font-size: 1.25rem;
  margin: 0 0 8px;
}

.v4-contact-block p {
  margin: 0;
  color: var(--v4-muted);
  line-height: 1.85;
  font-size: 0.9375rem;
}

.v4-form-panel {
  padding: 28px;
  background: var(--v4-white);
  border: 1px solid var(--v4-line);
  border-radius: var(--v4-radius-sm);
}

.v4-form-panel h2 {
  font-size: 1rem;
  margin: 0 0 20px;
}

.v4-form-row {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 14px;
}

.v4-field {
  display: flex;
  flex-direction: column;
  gap: 5px;
}

.v4-field.full {
  grid-column: 1 / -1;
}

.v4-field label {
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--v4-muted);
}

.v4-field input,
.v4-field select,
.v4-field textarea {
  padding: 10px 12px;
  border: 1px solid var(--v4-line);
  border-radius: var(--v4-radius-sm);
  font: inherit;
  background: var(--v4-paper);
}

.v4-field textarea {
  min-height: 110px;
  resize: vertical;
}

.v4-layers-summary {
  border: 1px solid var(--v4-line);
  border-radius: var(--v4-radius-sm);
  background: var(--v4-white);
  overflow: hidden;
}

.v4-layers-summary-row {
  display: grid;
  grid-template-columns: 11rem 1fr;
  gap: 18px;
  padding: 16px 22px;
  border-bottom: 1px solid var(--v4-line);
}

.v4-layers-summary-row:last-child {
  border-bottom: 0;
}

.v4-layers-summary-row dt {
  font-weight: 600;
  font-size: 0.875rem;
  margin: 0;
}

.v4-layers-summary-row dd {
  margin: 0;
  font-size: 0.875rem;
  color: var(--v4-muted);
  line-height: 1.75;
}

.v4-detail-panel {
  margin-top: 28px;
  padding: 22px 26px;
  background: var(--v4-white);
  border: 1px solid var(--v4-line);
  border-radius: var(--v4-radius-sm);
  min-height: 72px;
}

.v4-detail-panel h3 {
  font-size: 1rem;
  margin: 0 0 8px;
}

.v4-detail-panel p,
.v4-detail-placeholder {
  margin: 0;
  font-size: 0.9375rem;
  color: var(--v4-muted);
  line-height: 1.85;
}

.v4-model-section {
  padding-top: 0;
  padding-bottom: var(--v4-section-y);
}

.v4-gate-notice {
  padding: var(--v4-section-compact) 0;
}

/* Responsive */
@media (max-width: 1024px) {
  .v4-site main > section {
    padding: var(--v4-section-compact) 0;
  }

  .v4-hero-grid {
    grid-template-columns: 1fr;
    gap: 40px;
  }

  .v4-hero-copy,
  .v4-hero-visual {
    grid-column: span 1;
  }

  .v4-hero-visual {
    order: -1;
  }

  .v4-home-model-layout,
  .v4-minvista-card {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .v4-problem-grid,
  .v4-resource-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .v4-footer-grid {
    grid-template-columns: 1fr 1fr;
  }

  .v4-book-intro {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 768px) {
  .v4-container,
  .v4-wide {
    padding: 0 20px;
  }

  .v4-site main > section {
    padding: var(--v4-section-mobile) 0;
  }

  .v4-site main > section.v4-page-hero {
    padding-top: 48px;
  }

  .v4-hero {
    padding-top: 48px;
  }

  .v4-menu-toggle {
    display: block;
  }

  .v4-nav.nav-menu {
    display: none;
    position: absolute;
    top: 76px;
    left: 0;
    right: 0;
    flex-direction: column;
    background: var(--v4-paper);
    border-bottom: 1px solid var(--v4-line);
    padding: 16px 20px;
  }

  .v4-nav.nav-menu.is-open {
    display: flex;
  }

  .v4-header-cta {
    display: none;
  }

  .v4-problem-grid,
  .v4-resource-grid,
  .v4-grid-2,
  .v4-audience-grid,
  .v4-toc-grid,
  .v4-update-grid,
  .v4-form-row {
    grid-template-columns: 1fr;
  }

  .v4-model-mini-row {
    grid-template-columns: 1fr;
    gap: 6px;
  }

  .v4-minvista-card {
    padding: 28px;
  }

  .v4-footer-grid {
    grid-template-columns: 1fr;
  }
}