/* BalanceArc · brand.css — Causal Intelligence for High-Stakes Systems */
/* ================================================================== */

/* --- Custom Properties (Tokens) --- */
:root {
  --ink:       #122333;
  --ink-light: #203550;
  --paper:     #F8FBFC;
  --teal:      #0B8E87;
  --aqua:      #2ED3C6;
  --muted:     #5F7180;
  --line:      #1F3A52;
  --white:     #FFFFFF;
  --accent:    #0B8E87;

  /* Typography */
  --display: Aptos Display, Aptos, "Segoe UI", "PingFang SC", "Microsoft YaHei", Arial, sans-serif;
  --body: Aptos, "Segoe UI", "PingFang SC", "Microsoft YaHei", Arial, sans-serif;
  --mono: "SF Mono", "Fira Code", "Cascadia Code", monospace;

  /* Spacing */
  --space-xs: 4px;
  --space-sm: 8px;
  --space-md: 16px;
  --space-lg: 32px;
  --space-xl: 64px;
  --space-2xl: 96px;
  --space-3xl: 128px;

  /* Layout */
  --max-w: 1180px;
  --radius: 4px;

  /* Transitions */
  --ease: cubic-bezier(0.25, 0.1, 0.25, 1);
  --dur: 300ms;
}

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

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
  font-size: 16px;
}

body {
  font-family: var(--body);
  color: var(--ink);
  background: var(--paper);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* --- Reduced motion --- */
@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;
  }
}

/* --- Skip link --- */
.skip-link {
  position: absolute;
  top: -100%;
  left: var(--space-md);
  z-index: 10000;
  padding: var(--space-sm) var(--space-md);
  background: var(--teal);
  color: var(--white);
  font-weight: 600;
  border-radius: var(--radius);
  text-decoration: none;
}
.skip-link:focus { top: var(--space-sm); }

/* --- Focus --- */
:focus-visible {
  outline: 2px solid var(--aqua);
  outline-offset: 2px;
}

/* --- Utility --- */
.container {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

.section-heading {
  font-family: var(--display);
  font-size: clamp(1.75rem, 4vw, 2.75rem);
  font-weight: 700;
  line-height: 1.15;
  letter-spacing: -0.01em;
  margin-bottom: var(--space-md);
}

.section-sub {
  font-size: clamp(0.95rem, 1.5vw, 1.125rem);
  color: var(--muted);
  max-width: 640px;
}

/* ===================== HEADER / NAV ===================== */
.site-header {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 1000;
  background: var(--ink);
  color: var(--white);
  border-bottom: 1px solid rgba(255,255,255,0.06);
}

.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 56px;
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  text-decoration: none;
  color: var(--white);
  font-family: var(--display);
  font-weight: 700;
  font-size: 1.125rem;
  letter-spacing: -0.02em;
}
.nav-logo small {
  font-size: 0.625rem;
  font-weight: 400;
  color: var(--teal);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: var(--space-lg);
  list-style: none;
}

.nav-links a {
  color: rgba(255,255,255,0.7);
  text-decoration: none;
  font-size: 0.8125rem;
  font-weight: 500;
  letter-spacing: 0.02em;
  transition: color var(--dur) var(--ease);
}
.nav-links a:hover,
.nav-links a:focus-visible { color: var(--white); }

.lang-toggle {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
  background: rgba(255,255,255,0.08);
  border: 1px solid rgba(255,255,255,0.12);
  border-radius: 20px;
  padding: 3px;
  cursor: pointer;
  font-family: var(--body);
  font-size: 0.6875rem;
  font-weight: 600;
  color: rgba(255,255,255,0.5);
  transition: all var(--dur) var(--ease);
}
.lang-toggle:hover { border-color: var(--teal); }
.lang-toggle span {
  padding: 2px 8px;
  border-radius: 14px;
  transition: all var(--dur) var(--ease);
}
.lang-toggle span.active {
  background: var(--teal);
  color: var(--white);
}

.nav-cta {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: var(--teal);
  color: var(--white) !important;
  padding: 6px var(--space-md);
  border-radius: 20px;
  font-size: 0.8125rem;
  font-weight: 600;
  text-decoration: none;
  transition: background var(--dur) var(--ease);
}
.nav-cta:hover { background: #099e96; }

.nav-hamburger {
  display: none;
  background: none;
  border: none;
  color: var(--white);
  cursor: pointer;
  padding: var(--space-sm);
}

/* Mobile nav */
@media (max-width: 767px) {
  .nav-links {
    position: fixed;
    top: 56px; left: 0; right: 0;
    flex-direction: column;
    gap: 0;
    background: var(--ink);
    border-bottom: 1px solid rgba(255,255,255,0.08);
    padding: var(--space-md) 0;
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--dur) var(--ease), visibility var(--dur) var(--ease);
  }
  .nav-links.open {
    opacity: 1;
    visibility: visible;
  }
  .nav-links a, .nav-links .nav-cta {
    padding: var(--space-sm) var(--space-lg);
    width: 100%;
  }
  .nav-links .lang-toggle { margin: var(--space-sm) var(--space-lg); }
  .nav-hamburger { display: block; }
  .nav-inner { gap: var(--space-md); }
}

/* ===================== HERO ===================== */
.hero {
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  background: var(--ink);
  color: var(--white);
  padding: 88px 0 var(--space-xl);
  position: relative;
  overflow: hidden;
}
.hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background: radial-gradient(ellipse at 20% 50%, rgba(11,142,135,0.08) 0%, transparent 60%);
  pointer-events: none;
}

.hero-content {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 var(--space-lg);
  width: 100%;
}

.hero-eyebrow {
  font-family: var(--mono);
  font-size: 0.75rem;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--teal);
  margin-bottom: var(--space-lg);
}

.hero h1 {
  font-family: var(--display);
  font-size: clamp(2rem, 5.5vw, 4rem);
  font-weight: 700;
  line-height: 1.08;
  letter-spacing: -0.02em;
  max-width: 800px;
  margin-bottom: var(--space-lg);
}

.hero p {
  font-size: clamp(1rem, 1.8vw, 1.25rem);
  color: rgba(255,255,255,0.7);
  max-width: 560px;
  line-height: 1.6;
  margin-bottom: var(--space-xl);
}

.hero-ctas {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-md);
  margin-bottom: var(--space-2xl);
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-family: var(--body);
  font-size: 0.9375rem;
  font-weight: 600;
  padding: 12px 28px;
  border-radius: var(--radius);
  text-decoration: none;
  transition: all var(--dur) var(--ease);
  cursor: pointer;
  border: none;
}
.btn-primary {
  background: var(--teal);
  color: var(--white);
}
.btn-primary:hover {
  background: #099e96;
  transform: translateY(-1px);
}
.btn-secondary {
  background: rgba(255,255,255,0.06);
  color: var(--white);
  border: 1px solid rgba(255,255,255,0.12);
}
.btn-secondary:hover {
  background: rgba(255,255,255,0.1);
  border-color: var(--aqua);
}

/* --- Hero Rail SVG --- */
.hero-rail {
  width: 100%;
  max-width: 720px;
  margin-top: var(--space-lg);
}

/* ===================== SECTIONS ===================== */
.section {
  padding: var(--space-3xl) 0;
}
.section-dark {
  background: var(--ink);
  color: var(--white);
}
.section-dark .section-sub { color: rgba(255,255,255,0.55); }
.section-dark .section-heading { color: var(--white); }

.section-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

/* ===================== WHY (section 2) ===================== */
.why-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: var(--space-lg);
  margin-top: var(--space-xl);
}
.why-card {
  background: var(--white);
  border: 1px solid rgba(18,35,51,0.06);
  border-radius: var(--radius);
  padding: var(--space-lg);
}
.why-card h3 {
  font-family: var(--display);
  font-size: 1.125rem;
  font-weight: 600;
  margin-bottom: var(--space-sm);
  color: var(--ink);
}
.why-card p {
  font-size: 0.9375rem;
  color: var(--muted);
  line-height: 1.6;
}

/* ===================== MSIA (section 3) ===================== */
.msia-steps {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-lg);
  margin-top: var(--space-xl);
}
@media (max-width: 767px) {
  .msia-steps { grid-template-columns: 1fr; }
}

.msia-step {
  position: relative;
  padding: var(--space-lg);
  background: rgba(255,255,255,0.03);
  border: 1px solid rgba(255,255,255,0.06);
  border-radius: var(--radius);
}
.msia-step h3 {
  font-family: var(--display);
  font-size: 1.125rem;
  font-weight: 600;
  margin-bottom: var(--space-sm);
  color: var(--aqua);
}
.msia-step p {
  font-size: 0.9375rem;
  color: rgba(255,255,255,0.6);
}

/* ===================== BOUNDARY (section 4) ===================== */
.boundary-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-xl);
  margin-top: var(--space-xl);
}
@media (max-width: 767px) {
  .boundary-grid { grid-template-columns: 1fr; }
}

.boundary-col h3 {
  font-family: var(--display);
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: var(--space-lg);
}
.boundary-col.llm h3 { color: var(--muted); }
.boundary-col.cbm h3 { color: var(--teal); }

.boundary-items {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
}
.boundary-items li {
  padding: var(--space-md);
  border-left: 2px solid;
  font-size: 0.9375rem;
  line-height: 1.5;
}
.boundary-col.llm .boundary-items li {
  border-color: rgba(95,113,128,0.3);
  color: var(--muted);
}
.boundary-col.cbm .boundary-items li {
  border-color: var(--teal);
}
.boundary-col.cbm .boundary-items li strong {
  color: var(--teal);
}

/* --- Belief revision mini-rail --- */
.revision-flow {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  margin-top: var(--space-xl);
  flex-wrap: wrap;
}
.revision-node {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 90px;
  padding: var(--space-sm) var(--space-md);
  border-radius: var(--radius);
  font-size: 0.8125rem;
  font-weight: 600;
  text-align: center;
}
.revision-node.evidence { background: var(--teal); color: var(--white); }
.revision-node.belief { background: var(--ink); color: var(--white); }
.revision-node.action { background: var(--aqua); color: var(--ink); }
.revision-arrow {
  color: var(--teal);
  font-size: 1.25rem;
  font-weight: 700;
}
.revision-tags {
  display: flex;
  gap: var(--space-sm);
  justify-content: center;
  margin-top: var(--space-sm);
  font-size: 0.6875rem;
  color: var(--muted);
}
.revision-tags span {
  padding: 2px 8px;
  border: 1px dashed var(--muted);
  border-radius: 10px;
}

/* ===================== CAPABILITIES (section 5) ===================== */
.caps-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: var(--space-lg);
  margin-top: var(--space-xl);
}
.cap-card {
  padding: var(--space-lg);
  background: rgba(255,255,255,0.03);
  border: 1px solid rgba(255,255,255,0.06);
  border-radius: var(--radius);
}
.cap-card h3 {
  font-family: var(--display);
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: var(--space-sm);
  color: var(--aqua);
}
.cap-card p {
  font-size: 0.875rem;
  color: rgba(255,255,255,0.55);
  line-height: 1.5;
}

/* ===================== APPLICATIONS (section 6) ===================== */
.apps-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--space-lg);
  margin-top: var(--space-xl);
}

.app-card {
  position: relative;
  border-radius: var(--radius);
  overflow: hidden;
  min-height: 360px;
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  background-size: cover;
  background-position: center;
}
.app-card-overlay {
  padding: var(--space-lg);
  background: linear-gradient(to top, rgba(18,35,51,0.92) 40%, rgba(18,35,51,0.5) 80%, transparent);
  color: var(--white);
}
.app-card h3 {
  font-family: var(--display);
  font-size: 1.375rem;
  font-weight: 700;
  margin-bottom: var(--space-xs);
}
.app-card .app-badge {
  display: inline-block;
  font-size: 0.625rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--teal);
  margin-bottom: var(--space-sm);
}
.app-card p {
  font-size: 0.875rem;
  color: rgba(255,255,255,0.7);
  line-height: 1.55;
  margin-bottom: var(--space-sm);
}
.app-card .app-note {
  font-size: 0.75rem;
  color: rgba(255,255,255,0.5);
  font-style: italic;
  border-top: 1px solid rgba(255,255,255,0.1);
  padding-top: var(--space-sm);
}

/* ===================== DEPLOYMENT (section 7) ===================== */
.deploy-modes {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-md);
  margin-top: var(--space-xl);
}
@media (max-width: 767px) {
  .deploy-modes { grid-template-columns: 1fr; }
}
.deploy-mode {
  padding: var(--space-lg);
  background: rgba(255,255,255,0.03);
  border: 1px solid rgba(255,255,255,0.06);
  border-radius: var(--radius);
  text-align: center;
}
.deploy-mode h4 {
  font-family: var(--display);
  font-size: 1rem;
  font-weight: 600;
  color: var(--aqua);
  margin-bottom: var(--space-sm);
}
.deploy-mode p {
  font-size: 0.8125rem;
  color: rgba(255,255,255,0.5);
}

.trust-list {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: var(--space-md);
  margin-top: var(--space-xl);
  padding: var(--space-lg);
  background: rgba(255,255,255,0.03);
  border: 1px solid rgba(255,255,255,0.08);
  border-radius: var(--radius);
}
.trust-item {
  display: flex;
  gap: var(--space-sm);
  align-items: flex-start;
  font-size: 0.875rem;
  color: rgba(255,255,255,0.65);
}
.trust-item svg {
  width: 18px;
  height: 18px;
  flex-shrink: 0;
  margin-top: 2px;
  color: var(--teal);
}
.trust-item strong { color: var(--white); }

.training-note {
  margin-top: var(--space-md);
  font-size: 0.75rem;
  color: var(--teal);
  text-align: center;
  letter-spacing: 0.03em;
}

/* ===================== SIGNALS (section 8) ===================== */
.signals-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-xl);
  margin-top: var(--space-xl);
}
@media (max-width: 767px) {
  .signals-grid { grid-template-columns: 1fr; }
}
.signal-card {
  text-align: center;
}
.signal-card .number {
  font-family: var(--display);
  font-size: clamp(2.5rem, 5vw, 4rem);
  font-weight: 700;
  color: var(--teal);
  line-height: 1;
  letter-spacing: -0.03em;
}
.signal-card .label {
  font-size: 0.9375rem;
  color: var(--muted);
  margin-top: var(--space-sm);
}
.signal-card .detail {
  font-size: 0.75rem;
  color: var(--muted);
  margin-top: var(--space-xs);
}

.signals-disclaimer {
  margin-top: var(--space-xl);
  padding: var(--space-md);
  background: rgba(11,142,135,0.06);
  border: 1px solid rgba(11,142,135,0.15);
  border-radius: var(--radius);
  font-size: 0.75rem;
  color: var(--muted);
  line-height: 1.6;
  max-width: 640px;
  margin-left: auto;
  margin-right: auto;
  text-align: center;
}

/* ===================== PARTNERS (section 9) ===================== */
.partner-types {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-md);
  justify-content: center;
  margin-top: var(--space-xl);
}
.partner-type {
  padding: var(--space-sm) var(--space-lg);
  background: rgba(255,255,255,0.04);
  border: 1px solid rgba(255,255,255,0.08);
  border-radius: 20px;
  color: rgba(255,255,255,0.6);
  font-size: 0.9375rem;
}

.final-cta {
  text-align: center;
  margin-top: var(--space-2xl);
}
.final-cta h3 {
  font-family: var(--display);
  font-size: clamp(1.5rem, 3vw, 2rem);
  font-weight: 700;
  margin-bottom: var(--space-lg);
}
.final-cta .cta-email {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  color: var(--white);
  text-decoration: none;
  font-size: 1.125rem;
  font-weight: 500;
  padding: var(--space-md) var(--space-lg);
  background: rgba(255,255,255,0.04);
  border: 1px solid rgba(255,255,255,0.1);
  border-radius: var(--radius);
  transition: all var(--dur) var(--ease);
}
.final-cta .cta-email:hover {
  background: var(--teal);
  border-color: var(--teal);
}

/* ===================== FOOTER ===================== */
.site-footer {
  background: var(--ink);
  border-top: 1px solid rgba(255,255,255,0.04);
  padding: var(--space-xl) 0 var(--space-lg);
  color: rgba(255,255,255,0.4);
  font-size: 0.8125rem;
}
.footer-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 var(--space-lg);
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--space-md);
}
.footer-inner a {
  color: rgba(255,255,255,0.5);
  text-decoration: none;
}
.footer-inner a:hover { color: var(--teal); }

/* ===================== SCROLL REVEAL ===================== */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s var(--ease), transform 0.6s var(--ease);
}
.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}
@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; }
}

/* ===================== PRINT ===================== */
@media print {
  .site-header { position: relative; }
  .hero { min-height: auto; }
  .reveal { opacity: 1; transform: none; }
}