/* ============================================
   CardioCode AI — Vintage Notebook Landing Page
   Aesthetic: Aged paper, faint grid lines, 
   handwritten-feel serif headings, monospace 
   labels, warm sepia tones. Nostalgic.
   ============================================ */

/* === DESIGN TOKENS === */
:root {
  /* Type Scale */
  --text-xs: clamp(0.7rem, 0.65rem + 0.25vw, 0.8rem);
  --text-sm: clamp(0.8rem, 0.75rem + 0.25vw, 0.9rem);
  --text-base: clamp(0.9rem, 0.85rem + 0.25vw, 1rem);
  --text-lg: clamp(1.05rem, 0.95rem + 0.5vw, 1.3rem);
  --text-xl: clamp(1.4rem, 1.1rem + 1.25vw, 2.1rem);
  --text-2xl: clamp(1.8rem, 1.2rem + 2vw, 3rem);

  /* Spacing */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;
  --space-24: 6rem;
  --space-32: 8rem;

  /* Paper & Ink — warm sepia palette */
  --color-paper: #f5f0e8;
  --color-paper-warm: #ede7db;
  --color-paper-card: #faf7f1;
  --color-grid: rgba(160, 140, 110, 0.12);
  --color-grid-strong: rgba(160, 140, 110, 0.22);
  --color-ink: #2c2416;
  --color-ink-muted: #6b5d4d;
  --color-ink-faint: #9e8e7a;
  --color-ink-ghost: #c4b8a6;
  --color-border: rgba(120, 100, 75, 0.2);
  --color-border-strong: rgba(120, 100, 75, 0.35);
  --color-accent: #8b3a2a;
  --color-accent-hover: #722e21;
  --color-accent-text: #faf7f1;
  --color-highlight: rgba(139, 58, 42, 0.08);
  --color-success: #3d6b3d;
  --color-shadow: rgba(80, 60, 30, 0.06);
  --color-shadow-md: rgba(80, 60, 30, 0.1);

  /* Radius — slightly worn, not perfectly round */
  --radius-sm: 3px;
  --radius-md: 5px;
  --radius-lg: 8px;

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;

  /* Content widths */
  --content-narrow: 640px;
  --content-default: 960px;
  --content-wide: 1120px;

  /* Fonts */
  --font-display: 'Instrument Serif', Georgia, 'Times New Roman', serif;
  --font-body: 'DM Sans', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono: 'IBM Plex Mono', 'Menlo', monospace;
}

/* === RESET === */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; -webkit-font-smoothing: antialiased; }
body {
  font-family: var(--font-body);
  font-size: var(--text-base);
  line-height: 1.65;
  color: var(--color-ink);
  background: var(--color-paper);
  overflow-x: hidden;
  position: relative;
}
img { max-width: 100%; display: block; }
a { color: var(--color-accent); text-decoration: none; transition: color var(--transition-fast); }
a:hover { color: var(--color-accent-hover); }

/* === GRID BACKGROUND — faint notebook lines === */
.grid-bg {
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background-image:
    linear-gradient(var(--color-grid) 1px, transparent 1px),
    linear-gradient(90deg, var(--color-grid) 1px, transparent 1px);
  background-size: 24px 24px;
  opacity: 1;
}
/* Left margin line like a notebook */
.grid-bg::before {
  content: '';
  position: fixed;
  top: 0;
  left: min(8vw, 80px);
  width: 1px;
  height: 100%;
  background: rgba(180, 80, 60, 0.12);
}

/* === LAYOUT === */
.container { max-width: var(--content-default); margin: 0 auto; padding: 0 var(--space-6); position: relative; z-index: 1; }
.container-narrow { max-width: var(--content-narrow); }
section { padding: var(--space-20) 0; position: relative; z-index: 1; }

/* === TYPOGRAPHY === */
h1, h2, h3, h4 { font-family: var(--font-display); font-weight: 400; line-height: 1.2; letter-spacing: -0.01em; }
h1 { font-size: var(--text-2xl); }
h2 { font-size: var(--text-xl); }
h3 { font-size: var(--text-lg); }
h1 em, h2 em { font-style: italic; }

.section-header { text-align: center; margin-bottom: var(--space-12); }
.section-label {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: 400;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--color-ink-faint);
  margin-bottom: var(--space-3);
}
.section-desc {
  font-size: var(--text-base);
  color: var(--color-ink-muted);
  max-width: 560px;
  margin: var(--space-4) auto 0;
  line-height: 1.7;
}

/* === NOTEBOOK CARD — the core visual element === */
.notebook-card {
  background: var(--color-paper-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--space-8);
  position: relative;
  box-shadow: 0 1px 3px var(--color-shadow), 0 0 0 1px var(--color-shadow);
  /* Subtle paper texture via gradient noise */
  background-image: 
    radial-gradient(circle at 20% 80%, rgba(200, 180, 150, 0.04) 0%, transparent 50%),
    radial-gradient(circle at 80% 20%, rgba(180, 160, 130, 0.04) 0%, transparent 50%);
}
/* Card tab label — like a notebook tab */
.card-tab {
  position: absolute;
  top: -1px;
  left: var(--space-6);
  background: var(--color-paper-card);
  border: 1px solid var(--color-border);
  border-bottom: 1px solid var(--color-paper-card);
  border-radius: var(--radius-sm) var(--radius-sm) 0 0;
  padding: var(--space-1) var(--space-4);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: 500;
  color: var(--color-ink-faint);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  transform: translateY(-100%);
}

/* === BUTTONS === */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  font-family: var(--font-body);
  font-size: var(--text-sm);
  font-weight: 500;
  padding: var(--space-2) var(--space-6);
  border-radius: var(--radius-sm);
  border: 1px solid transparent;
  cursor: pointer;
  transition: all var(--transition-fast);
  text-decoration: none;
  line-height: 1.4;
}
.btn-primary {
  background: var(--color-accent);
  color: var(--color-accent-text);
  border-color: var(--color-accent);
}
.btn-primary:hover { background: var(--color-accent-hover); border-color: var(--color-accent-hover); color: var(--color-accent-text); }
.btn-outline {
  background: transparent;
  color: var(--color-ink);
  border-color: var(--color-border-strong);
}
.btn-outline:hover { background: var(--color-highlight); border-color: var(--color-ink-faint); color: var(--color-ink); }
.btn-ghost {
  background: transparent;
  color: var(--color-ink-muted);
  border: none;
  padding: var(--space-2) var(--space-4);
}
.btn-ghost:hover { color: var(--color-ink); }
.btn-lg { padding: var(--space-3) var(--space-8); font-size: var(--text-base); }
.btn-block { display: flex; width: 100%; }

/* === NAVIGATION === */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: rgba(245, 240, 232, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
}
.nav-inner {
  max-width: var(--content-wide);
  margin: 0 auto;
  padding: var(--space-3) var(--space-6);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-8);
}
.nav-logo {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  font-family: var(--font-display);
  font-size: var(--text-lg);
  color: var(--color-ink);
  text-decoration: none;
  flex-shrink: 0;
}
.nav-logo:hover { color: var(--color-ink); }
.nav-logo svg { flex-shrink: 0; }
.nav-links {
  display: flex;
  align-items: center;
  gap: var(--space-8);
}
.nav-links a {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: 400;
  letter-spacing: 0.04em;
  color: var(--color-ink-muted);
  text-decoration: none;
}
.nav-links a:hover { color: var(--color-ink); }
.nav-actions {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}
.nav-mobile-btn {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  color: var(--color-ink);
  padding: var(--space-2);
}
.nav-mobile {
  display: none;
  flex-direction: column;
  padding: var(--space-4) var(--space-6) var(--space-6);
  gap: var(--space-4);
  border-top: 1px solid var(--color-border);
}
.nav-mobile.active { display: flex; }
.nav-mobile a {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: var(--color-ink-muted);
}

@media (max-width: 768px) {
  .nav-links, .nav-actions { display: none; }
  .nav-mobile-btn { display: block; }
}

/* === HERO === */
.hero {
  padding: calc(var(--space-32) + 60px) 0 var(--space-16);
  text-align: center;
  position: relative;
  z-index: 1;
}
.hero-inner {
  max-width: 720px;
  margin: 0 auto;
  padding: 0 var(--space-6);
}
.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: 400;
  letter-spacing: 0.08em;
  color: var(--color-accent);
  background: var(--color-highlight);
  border: 1px solid rgba(139, 58, 42, 0.15);
  border-radius: var(--radius-sm);
  padding: var(--space-1) var(--space-4);
  margin-bottom: var(--space-8);
  text-transform: uppercase;
}
.badge-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--color-accent);
  animation: pulse 2s ease-in-out infinite;
}
@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.4; }
}
.hero h1 {
  margin-bottom: var(--space-6);
  color: var(--color-ink);
}
.hero-sub {
  font-size: var(--text-base);
  color: var(--color-ink-muted);
  line-height: 1.7;
  max-width: 580px;
  margin: 0 auto var(--space-10);
}
.hero-ctas {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: var(--space-4);
  margin-bottom: var(--space-4);
}
.hero-note {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-ink-faint);
  letter-spacing: 0.04em;
}

/* === STATUS BANNER === */
.status-banner { padding: 0 0 var(--space-16); }
.status-card { padding-top: calc(var(--space-8) + 8px); }
.status-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-6) var(--space-10);
}
.status-item { display: flex; flex-direction: column; gap: var(--space-1); }
.status-label {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: 500;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-ink-faint);
}
.status-value {
  font-size: var(--text-sm);
  color: var(--color-ink);
  line-height: 1.5;
}
@media (max-width: 640px) {
  .status-grid { grid-template-columns: 1fr; }
}

/* === PROBLEM SECTION === */
.problem-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-6);
}
.problem-item { padding: var(--space-6); }
.problem-num {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-ink-faint);
  letter-spacing: 0.08em;
  margin-bottom: var(--space-3);
}
.problem-item h3 { margin-bottom: var(--space-2); }
.problem-item p { font-size: var(--text-sm); color: var(--color-ink-muted); line-height: 1.65; }
@media (max-width: 640px) {
  .problem-grid { grid-template-columns: 1fr; }
}

/* === HOW IT WORKS === */
.steps-grid {
  max-width: 600px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 0;
}
.step-card {
  display: flex;
  gap: var(--space-6);
  padding: var(--space-6) 0;
  border-bottom: 1px dashed var(--color-border);
}
.step-card:last-of-type { border-bottom: none; }
.step-num {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-accent);
  letter-spacing: 0.08em;
  flex-shrink: 0;
  padding-top: 2px;
}
.step-content h3 { margin-bottom: var(--space-2); }
.step-content p { font-size: var(--text-sm); color: var(--color-ink-muted); line-height: 1.65; }
.step-connector {
  display: flex;
  justify-content: center;
  color: var(--color-ink-ghost);
  padding: var(--space-1) 0;
}

/* === FEATURES === */
.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-6);
}
.feature-card { padding: var(--space-6); }
.feature-icon {
  color: var(--color-accent);
  margin-bottom: var(--space-4);
  opacity: 0.8;
}
.feature-card h3 { margin-bottom: var(--space-3); }
.feature-card p { font-size: var(--text-sm); color: var(--color-ink-muted); line-height: 1.65; margin-bottom: var(--space-4); }
.feature-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}
.feature-list li {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-ink-faint);
  padding-left: var(--space-4);
  position: relative;
  letter-spacing: 0.02em;
}
.feature-list li::before {
  content: '—';
  position: absolute;
  left: 0;
  color: var(--color-ink-ghost);
}
@media (max-width: 768px) {
  .features-grid { grid-template-columns: 1fr; }
}

/* === INDUSTRY CONTEXT === */
.context-card { padding-top: calc(var(--space-8) + 8px); }
.context-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-6);
  margin-bottom: var(--space-6);
}
.context-item { display: flex; flex-direction: column; gap: var(--space-1); }
.context-num {
  font-family: var(--font-display);
  font-size: var(--text-xl);
  color: var(--color-ink);
  line-height: 1.1;
}
.context-label {
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
  line-height: 1.5;
}
.context-source {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  color: var(--color-ink-faint);
}
.context-note {
  font-size: var(--text-sm);
  color: var(--color-ink-muted);
  font-style: italic;
  border-top: 1px dashed var(--color-border);
  padding-top: var(--space-4);
  line-height: 1.65;
}
@media (max-width: 768px) {
  .context-grid { grid-template-columns: repeat(2, 1fr); }
}

/* === AGENTIC SECTION === */
.agent-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-6);
}
.agent-card { padding: var(--space-6); }
.agent-label {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: 500;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-accent);
  margin-bottom: var(--space-3);
  padding-bottom: var(--space-2);
  border-bottom: 1px dashed var(--color-border);
}
.agent-card p { font-size: var(--text-sm); color: var(--color-ink-muted); line-height: 1.65; }
@media (max-width: 640px) {
  .agent-grid { grid-template-columns: 1fr; }
}

/* === PRICING === */
.pricing-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-6);
  align-items: stretch;
}
.pricing-card { padding: var(--space-8); position: relative; display: flex; flex-direction: column; }
.pricing-card .btn-block { margin-top: auto; }
.pricing-featured {
  border-color: var(--color-accent);
  box-shadow: 0 2px 8px rgba(139, 58, 42, 0.08);
}
.pricing-badge {
  position: absolute;
  top: -1px;
  right: var(--space-6);
  background: var(--color-accent);
  color: var(--color-accent-text);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  padding: var(--space-1) var(--space-4);
  border-radius: 0 0 var(--radius-sm) var(--radius-sm);
  letter-spacing: 0.04em;
  text-transform: uppercase;
}
.pricing-header { margin-bottom: var(--space-4); }
.pricing-header h3 { font-size: var(--text-lg); margin-bottom: var(--space-1); }
.pricing-desc { font-size: var(--text-xs); color: var(--color-ink-faint); }
.pricing-price {
  display: flex;
  align-items: baseline;
  gap: var(--space-1);
  margin-bottom: var(--space-2);
}
.pricing-amount {
  font-family: var(--font-display);
  font-size: var(--text-xl);
  color: var(--color-ink);
}
.pricing-period {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-ink-faint);
}
.pricing-early {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-accent);
  letter-spacing: 0.02em;
  margin-bottom: var(--space-6);
  padding: var(--space-1) 0;
  border-bottom: 1px dashed var(--color-border);
}
.pricing-features {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
  margin-bottom: var(--space-8);
}
.pricing-features li {
  font-size: var(--text-sm);
  color: var(--color-ink-muted);
  padding-left: var(--space-6);
  position: relative;
  line-height: 1.4;
}
.pricing-features li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 5px;
  width: 12px;
  height: 12px;
  border: 1.5px solid var(--color-success);
  border-radius: 2px;
  background: none;
}
.pricing-features li::after {
  content: '';
  position: absolute;
  left: 3px;
  top: 8px;
  width: 6px;
  height: 3px;
  border-left: 1.5px solid var(--color-success);
  border-bottom: 1.5px solid var(--color-success);
  transform: rotate(-45deg);
}
@media (max-width: 768px) {
  .pricing-grid { grid-template-columns: 1fr; max-width: 400px; margin: 0 auto; }
}

/* === EARLY ACCESS CTA === */
.early-access { padding: var(--space-16) 0 var(--space-20); }
.cta-card {
  text-align: center;
  padding: calc(var(--space-10) + 8px) var(--space-10) var(--space-10);
}
.cta-card h2 { margin-bottom: var(--space-4); }
.cta-card p {
  font-size: var(--text-sm);
  color: var(--color-ink-muted);
  line-height: 1.7;
  max-width: 480px;
  margin: 0 auto var(--space-4);
}
.cta-actions {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: var(--space-4);
  margin-top: var(--space-8);
  margin-bottom: var(--space-4);
}
.cta-note {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-ink-faint);
  letter-spacing: 0.04em;
}

/* === FAQ === */
.faq { padding-bottom: var(--space-16); }
.faq-list {
  display: flex;
  flex-direction: column;
  gap: 0;
}
.faq-item {
  border-bottom: 1px dashed var(--color-border);
  padding: var(--space-4) 0;
}
.faq-item:first-child { border-top: 1px dashed var(--color-border); }
.faq-item summary {
  cursor: pointer;
  font-family: var(--font-display);
  font-size: var(--text-lg);
  color: var(--color-ink);
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  padding: var(--space-2) 0;
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after {
  content: '+';
  font-family: var(--font-mono);
  font-size: var(--text-base);
  color: var(--color-ink-faint);
  flex-shrink: 0;
  transition: transform var(--transition-fast);
}
.faq-item[open] summary::after {
  content: '−';
}
.faq-item p {
  font-size: var(--text-sm);
  color: var(--color-ink-muted);
  line-height: 1.7;
  padding: var(--space-2) 0 var(--space-3);
  max-width: 560px;
}

/* === FOOTER === */
.footer {
  border-top: 1px solid var(--color-border);
  padding: var(--space-12) 0 var(--space-8);
  position: relative;
  z-index: 1;
  background: rgba(245, 240, 232, 0.5);
}
.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: var(--space-8);
  margin-bottom: var(--space-8);
}
.footer-brand p {
  font-size: var(--text-sm);
  color: var(--color-ink-muted);
  margin-top: var(--space-3);
  max-width: 280px;
  line-height: 1.6;
}
.footer-col {
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}
.footer-col h4 {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: 500;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-ink-faint);
  margin-bottom: var(--space-1);
}
.footer-col a {
  font-size: var(--text-sm);
  color: var(--color-ink-muted);
}
.footer-col a:hover { color: var(--color-ink); }
.footer-bottom {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-top: var(--space-6);
  border-top: 1px dashed var(--color-border);
}
.footer-bottom p {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-ink-faint);
  letter-spacing: 0.02em;
}
@media (max-width: 768px) {
  .footer-grid { grid-template-columns: 1fr 1fr; gap: var(--space-8) var(--space-6); }
  .footer-brand { grid-column: 1 / -1; }
  .footer-bottom { flex-direction: column; gap: var(--space-2); text-align: center; }
}

/* === ANIMATION — subtle entrance === */
@keyframes fadeUp {
  from { opacity: 0; transform: translateY(16px); }
  to { opacity: 1; transform: translateY(0); }
}
.hero-inner > * {
  animation: fadeUp 0.6s ease both;
}
.hero-inner > *:nth-child(1) { animation-delay: 0.1s; }
.hero-inner > *:nth-child(2) { animation-delay: 0.2s; }
.hero-inner > *:nth-child(3) { animation-delay: 0.3s; }
.hero-inner > *:nth-child(4) { animation-delay: 0.4s; }
.hero-inner > *:nth-child(5) { animation-delay: 0.5s; }
.hero-inner > *:nth-child(6) { animation-delay: 0.6s; }

/* === SCROLL REVEAL (JS-powered) === */
.reveal { opacity: 0; transform: translateY(20px); transition: opacity 0.5s ease, transform 0.5s ease; }
.reveal.visible { opacity: 1; transform: translateY(0); }

/* === SELECTION === */
::selection {
  background: rgba(139, 58, 42, 0.15);
  color: var(--color-ink);
}

/* === SCROLLBAR — subtle === */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--color-ink-ghost); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--color-ink-faint); }

/* === PRINT === */
@media print {
  .grid-bg, .nav { display: none; }
  body { background: white; }
  .notebook-card { box-shadow: none; border: 1px solid #ccc; }
}