/* ============================================================
   GSDResponse — style.css
   DARK theme · near-black canvas · safety orange accent
   ============================================================ */

:root {
  --bg: #0E0F13;
  --bg-2: #15161B;
  --bg-3: #1A1C22;
  --surface: #16181E;
  --border: #262A33;
  --border-soft: #20242C;
  --text: #ECEEF2;
  --muted: #9BA3B0;
  --accent: #F97316;
  --accent-dark: #EA580C;
  --accent-light: #FB923C;
  --on-accent: #1A0E02;
  --radius: 12px;
  --max: 1160px;
}

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

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

body {
  font-family: "Inter", system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  font-size: 16px;
  line-height: 1.65;
  background-color: var(--bg);
  color: var(--text);
  overflow-x: hidden;
}

h1, h2, h3, h4 {
  font-family: "Space Grotesk", "Inter", sans-serif;
  line-height: 1.15;
  letter-spacing: -0.01em;
  color: var(--text);
}

p {
  color: var(--muted);
}

a {
  color: var(--accent-light);
  text-decoration: none;
  transition: color 0.2s ease;
}

a:hover {
  color: var(--accent);
}

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

.container {
  width: 100%;
  max-width: var(--max);
  margin: 0 auto;
  padding: 0 24px;
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 14px 26px;
  font-family: "Space Grotesk", "Inter", sans-serif;
  font-weight: 600;
  font-size: 15px;
  border-radius: 999px;
  border: 1px solid transparent;
  cursor: pointer;
  transition: background 0.2s ease, color 0.2s ease, border 0.2s ease, transform 0.2s ease;
}

.btn-primary {
  background: var(--accent);
  color: var(--on-accent);
}

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

.btn-ghost {
  background: transparent;
  color: var(--text);
  border-color: var(--border);
}

.btn-ghost:hover {
  border-color: var(--accent);
  color: var(--accent-light);
}

.btn-outline {
  background: transparent;
  color: var(--accent-light);
  border-color: var(--accent);
}

.btn-outline:hover {
  background: var(--accent);
  color: var(--on-accent);
}

/* ---------- Half-split navigation bar ---------- */
.navbar {
  position: sticky;
  top: 0;
  z-index: 200;
  display: flex;
  align-items: stretch;
  height: 68px;
  border-bottom: 1px solid var(--border);
  background: var(--bg);
}

.navbar-left {
  flex: 1 1 auto;
  background: var(--bg-2);
  display: flex;
  align-items: center;
  padding: 0 32px;
  border-right: 2px solid var(--bg-3);
}

.navbar-right {
  flex: 0 0 auto;
  background: var(--accent);
  display: flex;
  align-items: center;
  padding: 0 32px;
  gap: 26px;
}

.brand {
  font-family: "Space Grotesk", sans-serif;
  font-size: 22px;
  font-weight: 700;
  color: var(--text);
  letter-spacing: -0.02em;
}

.brand-accent {
  color: var(--accent);
}

.navbar-left .brand:hover {
  color: var(--text);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 24px;
}

.nav-links a {
  color: var(--on-accent);
  font-weight: 600;
  font-size: 15px;
  transition: color 0.2s ease;
}

.nav-links a:hover {
  color: var(--bg);
}

.nav-links .nav-cta {
  background: var(--on-accent);
  color: var(--accent-light);
  padding: 9px 20px;
  border-radius: 999px;
  font-weight: 700;
}

.nav-links .nav-cta:hover {
  background: var(--bg);
  color: var(--accent);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: transparent;
  border: none;
  cursor: pointer;
  padding: 8px;
}

.nav-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--on-accent);
  transition: transform 0.25s ease, opacity 0.25s ease;
}

.nav-toggle.open span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.nav-toggle.open span:nth-child(2) {
  opacity: 0;
}

.nav-toggle.open span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* ---------- Hero + signal waveform ---------- */
.hero {
  position: relative;
  padding: 96px 24px 40px;
  background: radial-gradient(1100px 520px at 50% -10%, var(--bg-3) 0%, var(--bg) 60%);
  border-bottom: 1px solid var(--border-soft);
  overflow-x: hidden;
}

.hero-grid {
  max-width: var(--max);
  margin: 0 auto;
}

.hero-eyebrow {
  font-family: "JetBrains Mono", monospace;
  font-size: 14px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent-light);
  margin-bottom: 20px;
}

.hero-title {
  font-size: clamp(38px, 6vw, 68px);
  font-weight: 700;
  max-width: 16ch;
  margin-bottom: 24px;
}

.hero-sub {
  max-width: 60ch;
  font-size: 19px;
  color: var(--muted);
  margin-bottom: 36px;
}

.hero-cta {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
}

.waveform {
  display: flex;
  align-items: flex-end;
  gap: 5px;
  height: 170px;
  max-width: var(--max);
  margin: 64px auto 0;
  padding: 0 4px;
  position: relative;
}

.waveform::before {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 2px;
  background: var(--border);
}

.waveform .spike {
  flex: 1 1 auto;
  height: var(--h);
  min-width: 2px;
  background: var(--accent);
  border-radius: 2px 2px 0 0;
  transform-origin: bottom;
  animation: spike-pulse 2.4s ease-in-out infinite;
  animation-delay: var(--d);
}

.waveform .spike.pulse {
  background: var(--accent-light);
}

@keyframes spike-pulse {
  0%, 100% { transform: scaleY(1); }
  50% { transform: scaleY(0.5); }
}

/* ---------- Stats band ---------- */
.stats-band {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1px;
  background: var(--border);
  border-bottom: 1px solid var(--border);
}

.stat {
  background: var(--bg-2);
  padding: 34px 28px;
  text-align: center;
}

.stat-value {
  display: block;
  font-family: "Space Grotesk", sans-serif;
  font-size: 42px;
  font-weight: 700;
  color: var(--accent);
  line-height: 1;
}

.stat-label {
  display: block;
  margin-top: 10px;
  font-size: 14px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--muted);
}

/* ---------- Statement (full-width row) ---------- */
.statement {
  padding: 96px 24px;
  max-width: 1040px;
  margin: 0 auto;
  text-align: center;
}

.statement-kicker {
  font-family: "JetBrains Mono", monospace;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--accent-light);
  font-size: 14px;
  margin-bottom: 20px;
}

.statement-title {
  font-size: clamp(30px, 4.5vw, 52px);
  font-weight: 700;
  max-width: 22ch;
  margin: 0 auto 24px;
}

.statement-body {
  max-width: 62ch;
  margin: 0 auto;
  font-size: 19px;
}

/* ---------- Section heads ---------- */
.section-head {
  max-width: 760px;
  margin-bottom: 56px;
}

.section-kicker {
  font-family: "JetBrains Mono", monospace;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--accent-light);
  font-size: 13px;
  margin-bottom: 16px;
}

.section-title {
  font-size: clamp(28px, 4vw, 44px);
  font-weight: 700;
  margin-bottom: 16px;
}

.section-lead {
  font-size: 18px;
  color: var(--muted);
}

/* ---------- Model (numbered list) ---------- */
.model-section {
  padding: 96px 0;
  background: var(--bg-2);
  border-top: 1px solid var(--border-soft);
  border-bottom: 1px solid var(--border-soft);
}

.model-list {
  list-style: none;
  counter-reset: model;
}

.model-item {
  display: grid;
  grid-template-columns: 120px 1fr;
  gap: 32px;
  padding: 36px 0;
  border-top: 1px solid var(--border-soft);
  align-items: start;
}

.model-item:last-child {
  border-bottom: 1px solid var(--border-soft);
}

.model-num {
  font-family: "JetBrains Mono", monospace;
  font-size: 40px;
  font-weight: 600;
  color: var(--accent);
  line-height: 1;
}

.model-body h3 {
  font-size: 26px;
  margin-bottom: 12px;
}

.model-body p {
  max-width: 60ch;
  font-size: 17px;
}

/* ---------- Capabilities (feature columns with numerals) ---------- */
.capabilities-section {
  padding: 96px 0;
}

.cap-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.cap-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px;
  transition: border-color 0.2s ease, transform 0.2s ease;
}

.cap-card:hover {
  border-color: var(--accent);
  transform: translateY(-4px);
}

.cap-num {
  display: inline-block;
  font-family: "JetBrains Mono", monospace;
  font-size: 15px;
  font-weight: 600;
  color: var(--on-accent);
  background: var(--accent);
  padding: 6px 12px;
  border-radius: 6px;
  margin-bottom: 20px;
}

.cap-card h3 {
  font-size: 22px;
  margin-bottom: 12px;
}

.cap-card p {
  font-size: 16px;
}

/* ---------- Compare table ---------- */
.compare-section {
  padding: 96px 0;
  background: var(--bg-2);
  border-top: 1px solid var(--border-soft);
  border-bottom: 1px solid var(--border-soft);
}

.compare-table-wrap {
  overflow-x: auto;
  border: 1px solid var(--border);
  border-radius: var(--radius);
}

.compare-table {
  width: 100%;
  border-collapse: collapse;
  min-width: 680px;
  background: var(--bg);
}

.compare-table th,
.compare-table td {
  text-align: left;
  padding: 20px 24px;
  border-bottom: 1px solid var(--border-soft);
  font-size: 16px;
}

.compare-table thead th {
  font-family: "Space Grotesk", sans-serif;
  font-size: 17px;
  color: var(--text);
  background: var(--bg-3);
}

.compare-table tbody th {
  font-family: "Space Grotesk", sans-serif;
  font-weight: 600;
  color: var(--text);
  width: 22%;
}

.compare-table td {
  color: var(--muted);
}

.compare-table .col-highlight {
  background: var(--on-accent);
  color: var(--accent-light);
  font-weight: 500;
}

.compare-table thead .col-highlight {
  background: var(--accent);
  color: var(--on-accent);
  font-weight: 700;
}

/* ---------- Tiers ---------- */
.tiers-section {
  padding: 96px 0;
}

.tier-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  align-items: stretch;
}

.tier-card {
  position: relative;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 36px 32px;
  display: flex;
  flex-direction: column;
}

.tier-card.tier-featured {
  border: 2px solid var(--accent);
  background: var(--bg-3);
}

.tier-badge {
  position: absolute;
  top: -14px;
  right: 24px;
  background: var(--accent);
  color: var(--on-accent);
  font-family: "JetBrains Mono", monospace;
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  padding: 6px 14px;
  border-radius: 999px;
}

.tier-card h3 {
  font-size: 26px;
  margin-bottom: 14px;
}

.tier-desc {
  font-size: 16px;
  margin-bottom: 24px;
}

.tier-list {
  list-style: none;
  margin-bottom: 32px;
  display: grid;
  gap: 12px;
}

.tier-list li {
  position: relative;
  padding-left: 28px;
  color: var(--muted);
  font-size: 16px;
}

.tier-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 8px;
  width: 12px;
  height: 12px;
  border-radius: 3px;
  background: var(--accent);
}

.tier-card .btn {
  margin-top: auto;
}

/* ---------- FAQ accordion ---------- */
.faq-section {
  padding: 96px 0;
  background: var(--bg-2);
  border-top: 1px solid var(--border-soft);
  border-bottom: 1px solid var(--border-soft);
}

.faq-list {
  max-width: 840px;
  display: grid;
  gap: 14px;
}

.faq-item {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg);
  overflow: hidden;
}

.faq-question {
  width: 100%;
  text-align: left;
  background: transparent;
  border: none;
  cursor: pointer;
  font-family: "Space Grotesk", sans-serif;
  font-size: 18px;
  font-weight: 600;
  color: var(--text);
  padding: 22px 24px;
  position: relative;
  padding-right: 60px;
}

.faq-question::after {
  content: "+";
  position: absolute;
  right: 24px;
  top: 50%;
  transform: translateY(-50%);
  font-size: 26px;
  font-weight: 400;
  color: var(--accent);
  transition: transform 0.2s ease;
}

.faq-item.open .faq-question::after {
  transform: translateY(-50%) rotate(45deg);
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease;
}

.faq-answer p {
  padding: 0 24px 24px;
  font-size: 16px;
}

.faq-item.open .faq-answer {
  max-height: 400px;
}

/* ---------- Contact ---------- */
.contact-section {
  padding: 96px 0;
}

.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 64px;
  align-items: start;
}

.contact-info .section-title {
  margin-bottom: 20px;
}

.contact-lead {
  font-size: 18px;
  margin-bottom: 36px;
}

.contact-list {
  list-style: none;
  display: grid;
  gap: 22px;
}

.contact-list li {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.contact-label {
  font-family: "JetBrains Mono", monospace;
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--muted);
}

.contact-list a,
.contact-list span {
  color: var(--text);
  font-size: 17px;
}

.contact-list a:hover {
  color: var(--accent-light);
}

.contact-form {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 36px;
  display: grid;
  gap: 12px;
}

.contact-form label {
  font-family: "Space Grotesk", sans-serif;
  font-weight: 600;
  font-size: 15px;
  color: var(--text);
  margin-top: 8px;
}

.contact-form input,
.contact-form textarea {
  width: 100%;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 14px 16px;
  color: var(--text);
  font-family: "Inter", sans-serif;
  font-size: 16px;
  transition: border-color 0.2s ease;
}

.contact-form input:focus,
.contact-form textarea:focus {
  outline: none;
  border-color: var(--accent);
}

.contact-form textarea {
  resize: vertical;
}

.contact-form .btn {
  margin-top: 12px;
}

.form-status {
  font-size: 14px;
  color: var(--accent-light);
  min-height: 20px;
}

/* ---------- Footer (multi-column + watermark) ---------- */
.site-footer {
  background: var(--bg-2);
  border-top: 1px solid var(--border);
  position: relative;
  overflow: hidden;
}

.footer-top {
  padding: 72px 0 48px;
  position: relative;
  z-index: 2;
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.6fr 1fr 1fr 1.2fr;
  gap: 40px;
}

.footer-brand p {
  margin-top: 16px;
  max-width: 34ch;
}

.footer-col h3 {
  font-size: 15px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--accent-light);
  margin-bottom: 18px;
}

.footer-col ul {
  list-style: none;
  display: grid;
  gap: 12px;
}

.footer-col a {
  color: var(--muted);
  font-size: 15px;
}

.footer-col a:hover {
  color: var(--accent-light);
}

.footer-col li {
  color: var(--muted);
  font-size: 15px;
}

.footer-watermark {
  position: absolute;
  right: -20px;
  bottom: -40px;
  font-family: "Space Grotesk", sans-serif;
  font-size: 240px;
  font-weight: 700;
  line-height: 1;
  color: var(--bg-3);
  z-index: 1;
  pointer-events: none;
  letter-spacing: -0.04em;
}

.footer-bottom {
  border-top: 1px solid var(--border-soft);
  padding: 22px 0;
  position: relative;
  z-index: 2;
}

.footer-bottom-inner {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  justify-content: space-between;
}

.footer-bottom p {
  font-size: 14px;
  color: var(--muted);
}

/* ---------- Scroll reveal ---------- */
.fade-up {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-up.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ---------- Responsive ---------- */
@media (max-width: 960px) {
  .cap-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .tier-grid {
    grid-template-columns: 1fr;
    max-width: 560px;
    margin: 0 auto;
  }

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

@media (max-width: 860px) {
  .navbar {
    flex-wrap: wrap;
  }

  .navbar-left {
    flex: 1 1 auto;
    padding: 0 20px;
  }

  .navbar-right {
    flex: 0 0 auto;
    padding: 0 20px;
    gap: 0;
  }

  .nav-toggle {
    display: flex;
  }

  .nav-links {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    background: var(--bg-2);
    border-bottom: 1px solid var(--border);
    padding: 8px 0;
    display: none;
  }

  .nav-links.open {
    display: flex;
  }

  .nav-links a {
    color: var(--text);
    padding: 16px 24px;
    border-top: 1px solid var(--border-soft);
  }

  .nav-links a:first-child {
    border-top: none;
  }

  .nav-links .nav-cta {
    background: var(--accent);
    color: var(--on-accent);
    margin: 16px 24px;
    text-align: center;
  }

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

  .contact-grid {
    grid-template-columns: 1fr;
    gap: 48px;
  }
}

@media (max-width: 640px) {
  .hero {
    padding-top: 64px;
  }

  .model-item {
    grid-template-columns: 1fr;
    gap: 12px;
  }

  .cap-grid {
    grid-template-columns: 1fr;
  }

  .footer-grid {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .compare-table th,
  .compare-table td {
    padding: 16px;
  }
}