/* ════════════════════════════════════════════════════
   THE MARKETING HELIX — Global Styles
   ════════════════════════════════════════════════════ */

@import url('https://fonts.googleapis.com/css2?family=IBM+Plex+Sans:wght@400;600&family=IBM+Plex+Mono&display=swap');

:root {
  --model-black:    #111827;
  --research-white: #FFFFFF;
  --motion-blue:    #2563EB;
  --trust-purple:   #7C3AED;
  --signal-teal:    #14B8A6;
  --fade-gray:      #D1D5DB;
  --axis-slate:     #475569;
  --bg-off:         #F8FAFC;

  --font-sans: 'IBM Plex Sans', system-ui, sans-serif;
  --font-mono: 'IBM Plex Mono', monospace;

  --nav-height: 64px;
  --max-width:  1100px;
  --section-pad: 80px;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; }

body {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.65;
  color: var(--model-black);
  background: var(--research-white);
  -webkit-font-smoothing: antialiased;
}

/* ── TYPOGRAPHY ── */

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-sans);
  font-weight: 600;
  line-height: 1.2;
  color: var(--model-black);
}

h1 { font-size: clamp(2rem, 4vw, 3rem); }
h2 { font-size: clamp(1.35rem, 2.5vw, 1.9rem); }
h3 { font-size: 1.1rem; }

p { margin-bottom: 1.25em; }
p:last-child { margin-bottom: 0; }

a { color: var(--motion-blue); text-decoration: none; }
a:hover { text-decoration: underline; }

dfn {
  font-style: normal;
  font-weight: 600;
  color: var(--model-black);
  border-bottom: 1px dotted var(--axis-slate);
}

blockquote {
  border-left: 3px solid var(--motion-blue);
  padding: 1.1rem 1.5rem;
  margin: 2rem 0;
  background: var(--bg-off);
  font-size: 1.025rem;
  color: var(--axis-slate);
  line-height: 1.75;
}

/* ── LAYOUT ── */

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 2rem;
}

.section {
  padding: var(--section-pad) 0;
}

.section + .section {
  border-top: 1px solid var(--fade-gray);
}

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

/* ── NAV ── */

.site-nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--research-white);
  border-bottom: 1px solid var(--fade-gray);
  height: var(--nav-height);
}

.nav-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 2rem;
  height: 100%;
  display: flex;
  align-items: center;
  gap: 0;
}

.nav-logo {
  font-family: var(--font-sans);
  font-weight: 600;
  font-size: 0.85rem;
  letter-spacing: -0.02em;
  line-height: 1.15;
  color: var(--model-black);
  text-decoration: none;
  flex-shrink: 0;
  margin-right: 1.5rem;
}
.nav-logo:hover { color: var(--motion-blue); text-decoration: none; }

.nav-primary {
  display: flex;
  list-style: none;
  flex: 1;
  gap: 0;
}

.nav-item { position: relative; }

.nav-item > a {
  display: flex;
  align-items: center;
  gap: 0.25rem;
  height: var(--nav-height);
  padding: 0 0.95rem;
  font-size: 0.85rem;
  font-weight: 400;
  color: var(--axis-slate);
  text-decoration: none;
  white-space: nowrap;
  transition: color 0.15s;
}

.nav-item > a::after {
  content: '▾';
  font-size: 0.6rem;
  opacity: 0.5;
  margin-top: 1px;
}

.nav-item > a:hover,
.nav-item:focus-within > a,
.nav-item:hover > a {
  color: var(--model-black);
}

/* Dropdown */
.nav-dropdown {
  display: none;
  position: absolute;
  top: calc(var(--nav-height) - 1px);
  left: 0;
  min-width: 240px;
  background: var(--research-white);
  border: 1px solid var(--fade-gray);
  border-top: 2px solid var(--motion-blue);
  padding: 0.4rem 0;
  box-shadow: 0 8px 24px rgba(0,0,0,0.08);
  z-index: 200;
}

.nav-item:hover .nav-dropdown,
.nav-item:focus-within .nav-dropdown {
  display: block;
}

.nav-dropdown a {
  display: flex;
  align-items: center;
  padding: 0.65rem 1.25rem;
  font-size: 0.83rem;
  color: var(--axis-slate);
  text-decoration: none;
  min-height: 44px;
  transition: background 0.1s, color 0.1s;
}

.nav-dropdown a:hover {
  background: var(--bg-off);
  color: var(--model-black);
}

/* CTA */
.nav-cta {
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--motion-blue);
  border: 1.5px solid var(--motion-blue);
  padding: 0.45rem 1rem;
  border-radius: 3px;
  text-decoration: none;
  white-space: nowrap;
  min-height: 36px;
  display: flex;
  align-items: center;
  margin-left: auto;
  flex-shrink: 0;
  transition: background 0.15s, color 0.15s;
}
.nav-cta:hover { background: var(--motion-blue); color: #fff; text-decoration: none; }

/* Hamburger */
.nav-hamburger {
  display: none;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 10px;
  margin-left: auto;
  min-width: 44px;
  min-height: 44px;
}
.nav-hamburger span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--model-black);
  transition: transform 0.2s, opacity 0.2s;
}

/* ── MOBILE OVERLAY ── */

.mobile-nav-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: var(--research-white);
  z-index: 99;
  padding: calc(var(--nav-height) + 1.5rem) 2rem 2rem;
  overflow-y: auto;
}

.mobile-nav-overlay.is-open { display: block; }

.mobile-nav-section { margin-bottom: 2rem; }

.mobile-nav-section h3 {
  font-size: 0.68rem;
  font-weight: 600;
  letter-spacing: 0.13em;
  text-transform: uppercase;
  color: var(--axis-slate);
  margin-bottom: 0.6rem;
  padding-bottom: 0.5rem;
  border-bottom: 1px solid var(--fade-gray);
}

.mobile-nav-section a {
  display: flex;
  align-items: center;
  padding: 0.75rem 0;
  font-size: 0.95rem;
  color: var(--model-black);
  text-decoration: none;
  border-bottom: 1px solid var(--bg-off);
  min-height: 44px;
}
.mobile-nav-section a:hover { color: var(--motion-blue); }

/* ── HERO ── */

.hero {
  padding: 96px 0 80px;
  background: var(--research-white);
}

.hero-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 2rem;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4rem;
  align-items: center;
}

.hero-label {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--axis-slate);
  margin-bottom: 1.1rem;
}

.hero h1 {
  font-size: clamp(2.1rem, 4vw, 3.1rem);
  line-height: 1.1;
  margin-bottom: 1.25rem;
}

.hero-subhead {
  font-size: 1.025rem;
  color: var(--axis-slate);
  line-height: 1.7;
  margin-bottom: 2rem;
}

.hero-links {
  display: flex;
  gap: 2.5rem;
  flex-wrap: wrap;
}

.hero-links a {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--motion-blue);
}
.hero-links a:hover { text-decoration: underline; }

.hero-visual {
  display: flex;
  justify-content: center;
  align-items: center;
}

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

/* ── SECTION LABELS ── */

.section-label {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.13em;
  text-transform: uppercase;
  color: var(--axis-slate);
  margin-bottom: 0.75rem;
  display: block;
}

.section-heading {
  font-size: clamp(1.35rem, 2.5vw, 1.9rem);
  margin-bottom: 1.5rem;
}

.section-body {
  max-width: 680px;
  color: var(--axis-slate);
  line-height: 1.75;
}

/* ── FORCE CARDS ── */

.forces-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
  margin-top: 2.5rem;
}

.force-card {
  border: 1px solid var(--fade-gray);
  border-top: 3px solid var(--motion-blue);
  padding: 1.75rem 1.5rem;
  background: var(--research-white);
}

.force-card--trust    { border-top-color: var(--trust-purple); }
.force-card--relevance{ border-top-color: var(--motion-blue); }
.force-card--timing   { border-top-color: var(--signal-teal); }

.force-card-icon { margin-bottom: 1.1rem; }

.force-card h3 {
  font-size: 1rem;
  margin-bottom: 0.5rem;
}

.force-card p {
  font-size: 0.875rem;
  color: var(--axis-slate);
  line-height: 1.65;
  margin: 0;
}

.force-card-link {
  display: inline-block;
  margin-top: 1.25rem;
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--motion-blue);
}

/* ── DIAGRAM ── */

.diagram-section {
  background: var(--bg-off);
}

.diagram-wrap {
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  margin-top: 2.5rem;
}

.diagram-wrap svg {
  max-width: 100%;
  height: auto;
  display: block;
  margin: 0 auto;
}

.diagram-caption {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--axis-slate);
  text-align: center;
  margin-top: 1.25rem;
  letter-spacing: 0.06em;
}

/* ── COMPARISON TABLE ── */

.comparison-table-wrap {
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  margin-top: 2.5rem;
}

.comparison-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
  min-width: 560px;
}

.comparison-table thead th {
  text-align: left;
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.09em;
  text-transform: uppercase;
  color: var(--axis-slate);
  padding: 0.75rem 1.1rem;
  border-bottom: 2px solid var(--fade-gray);
}

.comparison-table thead th:not(:first-child) { text-align: center; }

.comparison-table td {
  padding: 0.85rem 1.1rem;
  border-bottom: 1px solid var(--fade-gray);
  color: var(--axis-slate);
  vertical-align: top;
  line-height: 1.5;
}

.comparison-table td:first-child {
  font-weight: 600;
  color: var(--model-black);
  white-space: nowrap;
}

.comparison-table td:not(:first-child) { text-align: center; }

.comparison-table tr:last-child td { border-bottom: none; }

.comparison-table tr:hover td { background: var(--bg-off); }

/* ── PAGE HEADER (interior pages) ── */

.page-header {
  padding: 64px 0 48px;
  border-bottom: 1px solid var(--fade-gray);
}

.page-header h1 {
  font-size: clamp(1.8rem, 3.5vw, 2.6rem);
  margin-bottom: 0.75rem;
}

.page-header .lead {
  font-size: 1.025rem;
  color: var(--axis-slate);
  max-width: 640px;
  line-height: 1.7;
}

/* ── PAGE CONTENT ── */

.page-content {
  max-width: 720px;
}

.page-content h2 {
  margin-top: 2.75rem;
  margin-bottom: 1rem;
  padding-top: 2rem;
  border-top: 1px solid var(--fade-gray);
}

.page-content h2:first-child {
  margin-top: 0;
  padding-top: 0;
  border-top: none;
}

.page-content h3 {
  margin-top: 1.75rem;
  margin-bottom: 0.75rem;
}

.page-content p {
  color: var(--axis-slate);
  line-height: 1.75;
}

/* ── GLOSSARY ── */

.glossary-list { margin-top: 2rem; }

.glossary-term {
  padding: 1.75rem 0;
  border-bottom: 1px solid var(--fade-gray);
}

.glossary-term:last-child { border-bottom: none; }

.glossary-term dt {
  font-family: var(--font-mono);
  font-size: 0.88rem;
  color: var(--model-black);
  margin-bottom: 0.4rem;
}

.glossary-term dd {
  font-size: 0.95rem;
  color: var(--axis-slate);
  line-height: 1.7;
  margin: 0;
}

/* ── RELATED READING ── */

.related-reading {
  background: var(--bg-off);
  border-top: 1px solid var(--fade-gray);
  padding: 2.5rem 0;
}

.related-reading h3 {
  font-size: 0.68rem;
  font-weight: 600;
  letter-spacing: 0.13em;
  text-transform: uppercase;
  color: var(--axis-slate);
  margin-bottom: 1rem;
}

.related-links {
  display: flex;
  gap: 2.5rem;
  flex-wrap: wrap;
}

.related-links a {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--motion-blue);
}

/* ── POST-PURCHASE CALLOUT ── */

.teal-callout {
  border-left: 3px solid var(--signal-teal);
  padding: 1.1rem 1.5rem;
  margin: 2rem 0;
  background: var(--bg-off);
  font-size: 0.95rem;
  color: var(--axis-slate);
  line-height: 1.7;
}

/* ── FORCE PAGE DETAIL ── */

.force-detail-header {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 2rem;
}

.force-indicator {
  width: 8px;
  height: 56px;
  border-radius: 4px;
  flex-shrink: 0;
}

.force-indicator--trust    { background: var(--trust-purple); }
.force-indicator--relevance{ background: var(--motion-blue); }
.force-indicator--timing   { background: var(--signal-teal); }

/* ── APPLICATIONS ── */

.application-block {
  padding: 2.5rem 0;
  border-bottom: 1px solid var(--fade-gray);
}
.application-block:last-child { border-bottom: none; }

.application-block h2 {
  font-size: 1.3rem;
  margin-bottom: 1rem;
}

/* ── PRINCIPLES ── */

.principle-item {
  display: grid;
  grid-template-columns: 2.5rem 1fr;
  gap: 1rem;
  padding: 2rem 0;
  border-bottom: 1px solid var(--fade-gray);
  align-items: start;
}

.principle-item:last-child { border-bottom: none; }

.principle-num {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--motion-blue);
  font-weight: 600;
  padding-top: 0.2rem;
}

.principle-item h3 { margin-bottom: 0.6rem; }

.principle-item p {
  font-size: 0.9rem;
  color: var(--axis-slate);
  line-height: 1.7;
  margin: 0;
}

/* ── FOOTER ── */

.site-footer {
  background: var(--model-black);
  color: rgba(255,255,255,0.65);
  padding: 3.5rem 0 2.5rem;
}

.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 2rem;
}

.footer-logo {
  font-family: var(--font-sans);
  font-weight: 600;
  font-size: 0.85rem;
  letter-spacing: -0.02em;
  line-height: 1.15;
  color: var(--research-white);
  text-decoration: none;
  display: inline-block;
  margin-bottom: 0.4rem;
}
.footer-logo:hover { text-decoration: none; color: rgba(255,255,255,0.8); }

.footer-tagline {
  font-size: 0.78rem;
  color: rgba(255,255,255,0.4);
  font-style: italic;
  margin-bottom: 2rem;
}

.footer-nav {
  display: flex;
  gap: 1.75rem;
  flex-wrap: wrap;
  margin-bottom: 1.25rem;
}

.footer-nav a {
  font-size: 0.82rem;
  color: rgba(255,255,255,0.55);
  text-decoration: none;
  min-height: 44px;
  display: flex;
  align-items: center;
}
.footer-nav a:hover { color: #fff; text-decoration: none; }

.footer-related {
  font-size: 0.8rem;
  color: rgba(255,255,255,0.4);
  margin-bottom: 2.5rem;
}
.footer-related a { color: rgba(255,255,255,0.55); text-decoration: none; }
.footer-related a:hover { color: #fff; }

.footer-legal {
  font-size: 0.73rem;
  color: rgba(255,255,255,0.3);
  padding-top: 1.5rem;
  border-top: 1px solid rgba(255,255,255,0.1);
  line-height: 1.6;
}

/* ── UTILITIES ── */

.text-mono { font-family: var(--font-mono); font-size: 0.875em; }
.text-muted { color: var(--axis-slate); }
.sr-only {
  position: absolute; width: 1px; height: 1px;
  padding: 0; margin: -1px; overflow: hidden;
  clip: rect(0,0,0,0); white-space: nowrap; border: 0;
}

/* ── RESPONSIVE ── */

@media (max-width: 1200px) {
  :root { --section-pad: 64px; }
}

@media (max-width: 768px) {
  :root { --section-pad: 48px; }

  .nav-primary, .nav-cta { display: none; }
  .nav-hamburger { display: flex; }

  .hero { padding: 56px 0 44px; }
  .hero-inner { grid-template-columns: 1fr; gap: 2.5rem; }
  .hero-visual { order: -1; }

  .forces-grid { grid-template-columns: 1fr; gap: 1rem; }

  .page-header { padding: 44px 0 36px; }

  .principle-item { grid-template-columns: 1fr; gap: 0.5rem; }

  .footer-nav { flex-direction: column; gap: 0; }
  .footer-nav a { border-bottom: 1px solid rgba(255,255,255,0.07); }

  .related-links { flex-direction: column; gap: 1rem; }
}

@media (max-width: 480px) {
  h1 { font-size: 1.85rem; }
  h2 { font-size: 1.25rem; }

  .hero h1 { font-size: 1.9rem; }
  .hero-subhead { font-size: 0.95rem; }

  .hero-links { gap: 1.5rem; }

  .container { padding: 0 1.25rem; }
}