/* PocketAI Design System Stylesheet
   Matches strategy/02-design-system.md:
   Green accent (#1E764A / #3DB27E), Graphite neutrals, SF-like system font stack.
   Zero external dependencies, zero web fonts, zero trackers. */

:root {
  /* Color Tokens - Light */
  --bg-canvas: #F7F6F3;
  --bg-surface: #FFFFFF;
  --bg-raised: #FFFFFF;
  --bg-sunken: #EFEDE8;
  --line-hairline: rgba(0, 0, 0, 0.08);
  --line-strong: rgba(0, 0, 0, 0.16);
  --text-primary: #15161A;
  --text-secondary: rgba(21, 22, 26, 0.62);
  --text-tertiary: rgba(21, 22, 26, 0.40);
  --accent: #1E764A;
  --accent-soft: rgba(31, 122, 77, 0.12);
  --accent-on-accent: #FFFFFF;
  --mark: #1F7A4D; /* mark.green: the mark only, never accent */
  --status-ok: #1F8A5B;
  --status-warn: #B7791F;
  --status-bad: #C2362F;
  --status-info: #2F6FDB;
  --privacy-local: #1F8A5B;

  /* Typography */
  --font-system: -apple-system, BlinkMacSystemFont, "SF Pro", "SF Pro Text", "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --font-display: ui-rounded, "SF Pro Rounded", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --font-mono: ui-monospace, "SF Mono", Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;

  /* Spacing Scale (pt / px) */
  --space-2: 2px;
  --space-4: 4px;
  --space-6: 6px;
  --space-8: 8px;
  --space-10: 10px;
  --space-12: 12px;
  --space-16: 16px;
  --space-20: 20px;
  --space-24: 24px;
  --space-32: 32px;
  --space-40: 40px;
  --space-56: 56px;
  --space-80: 80px;

  /* Corner Radius */
  --radius-chip: 8px;
  --radius-card: 14px;
  --radius-bubble: 20px;
  --radius-capsule: 9999px;

  /* Elevation */
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.06);
  --shadow-card: 0 6px 20px rgba(0, 0, 0, 0.05);
  --shadow-float: 0 12px 32px rgba(0, 0, 0, 0.08);

  /* Layout */
  --max-width: 1040px;
  --content-width: 740px;
}

@media (prefers-color-scheme: dark) {
  :root {
    /* Color Tokens - Dark */
    --bg-canvas: #0E0F12;
    --bg-surface: #16181C;
    --bg-raised: #1D2026;
    --bg-sunken: #0A0B0D;
    --line-hairline: rgba(255, 255, 255, 0.08);
    --line-strong: rgba(255, 255, 255, 0.16);
    --text-primary: #F2F1EE;
    --text-secondary: rgba(242, 241, 238, 0.64);
    --text-tertiary: rgba(242, 241, 238, 0.40);
    --accent: #3DB27E;
    --accent-soft: rgba(61, 178, 126, 0.18);
    --accent-on-accent: #0C1A12;
    --mark: #4ADE9A;
    --status-ok: #3CCB8A;
    --status-warn: #F2B84B;
    --status-bad: #FF6B61;
    --status-info: #6EA2FF;
    --privacy-local: #3CCB8A;

    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.4);
    --shadow-card: 0 6px 20px rgba(0, 0, 0, 0.35);
    --shadow-float: 0 12px 32px rgba(0, 0, 0, 0.5);
  }
}

/* CSS Reset & Base */
*, *::before, *::after {
  box-sizing: border-box;
}

html {
  font-family: var(--font-system);
  background-color: var(--bg-canvas);
  color: var(--text-primary);
  font-size: 16px;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  scroll-behavior: smooth;
}

body {
  margin: 0;
  padding: 0;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  background-color: var(--bg-canvas);
}

/* Typography Defaults */
h1, h2, h3, h4, h5, h6 {
  color: var(--text-primary);
  font-weight: 600;
  line-height: 1.25;
  margin-top: 0;
}

h1 {
  font-family: var(--font-display);
  font-size: clamp(2rem, 5vw, 3.25rem);
  letter-spacing: -0.025em;
  line-height: 1.15;
}

h2 {
  font-family: var(--font-display);
  font-size: clamp(1.5rem, 3.5vw, 2.25rem);
  letter-spacing: -0.02em;
  margin-bottom: var(--space-12);
}

h3 {
  font-size: 1.25rem;
  letter-spacing: -0.01em;
  margin-bottom: var(--space-8);
}

p {
  margin-top: 0;
  margin-bottom: var(--space-16);
  color: var(--text-secondary);
  font-size: 1.0625rem;
  line-height: 1.6;
}

p.lead {
  font-size: clamp(1.125rem, 2.5vw, 1.375rem);
  color: var(--text-secondary);
  line-height: 1.5;
  max-width: 680px;
}

a {
  color: var(--accent);
  text-decoration: none;
  transition: opacity 0.15s ease;
}

a:hover {
  text-decoration: underline;
}

/* Focus styles for keyboard accessibility */
a:focus-visible,
button:focus-visible,
summary:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 4px;
}

code, kbd, samp, pre {
  font-family: var(--font-mono);
  font-size: 0.9em;
}

code {
  background: var(--bg-sunken);
  padding: 0.15em 0.4em;
  border-radius: 6px;
  border: 1px solid var(--line-hairline);
  color: var(--text-primary);
}

/* Layout Utilities */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin-left: auto;
  margin-right: auto;
  padding-left: var(--space-16);
  padding-right: var(--space-16);
}

.content-container {
  width: 100%;
  max-width: var(--content-width);
  margin-left: auto;
  margin-right: auto;
  padding-left: var(--space-16);
  padding-right: var(--space-16);
}

/* Navigation Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: var(--bg-canvas);
  border-bottom: 1px solid var(--line-hairline);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}

.nav-wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
  gap: var(--space-16);
}

.brand-link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-8);
  font-family: var(--font-display);
  font-size: 1.25rem;
  font-weight: 600;
  letter-spacing: -0.015em;
  color: var(--text-primary);
  text-decoration: none;
}

.brand-link:hover {
  text-decoration: none;
  opacity: 0.9;
}

.brand-link b,
.accent-text {
  color: var(--accent);
  font-weight: 600;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: var(--space-20);
  list-style: none;
  margin: 0;
  padding: 0;
}

.nav-links a {
  color: var(--text-secondary);
  font-size: 0.9375rem;
  font-weight: 500;
  text-decoration: none;
  transition: color 0.15s ease;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--text-primary);
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: var(--space-12);
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-8);
  font-family: var(--font-system);
  font-size: 1rem;
  font-weight: 600;
  line-height: 1;
  padding: 12px 22px;
  border-radius: var(--radius-capsule);
  text-decoration: none;
  cursor: pointer;
  border: 1px solid transparent;
  transition: transform 0.12s ease, opacity 0.15s ease, background-color 0.15s ease;
  min-height: 44px; /* Accessible touch target */
}

.btn:active {
  transform: scale(0.98);
}

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

.btn-primary:hover {
  text-decoration: none;
  opacity: 0.92;
}

.btn-secondary {
  background-color: var(--bg-surface);
  color: var(--text-primary);
  border: 1px solid var(--line-strong);
}

.btn-secondary:hover {
  text-decoration: none;
  background-color: var(--bg-sunken);
}

.btn-sm {
  font-size: 0.875rem;
  padding: 8px 16px;
  min-height: 36px;
}

/* Badges and Chips */
.badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-6);
  font-size: 0.8125rem;
  font-weight: 600;
  padding: 4px 12px;
  border-radius: var(--radius-capsule);
  letter-spacing: 0.01em;
}

.badge-accent {
  background-color: var(--accent-soft);
  color: var(--accent);
}

.badge-ok {
  background-color: rgba(31, 138, 91, 0.12);
  color: var(--status-ok);
}

.badge-local {
  background-color: rgba(31, 138, 91, 0.12);
  color: var(--privacy-local);
}

.badge-dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background-color: currentColor;
}

/* Hero Section */
.hero {
  padding-top: var(--space-56);
  padding-bottom: var(--space-56);
  text-align: center;
}

.hero .badge {
  margin-bottom: var(--space-20);
}

.hero h1 {
  max-width: 820px;
  margin-left: auto;
  margin-right: auto;
  margin-bottom: var(--space-16);
}

.hero .lead {
  margin-left: auto;
  margin-right: auto;
  margin-bottom: var(--space-32);
}

.hero-actions {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-16);
  flex-wrap: wrap;
  margin-bottom: var(--space-40);
}

/* Hero Hardware Visual */
.hero-visual {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  margin-top: var(--space-20);
}

.hardware-card {
  background: var(--bg-surface);
  border: 1px solid var(--line-hairline);
  border-radius: var(--radius-bubble);
  padding: var(--space-24) var(--space-32);
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-16);
  box-shadow: var(--shadow-card);
  max-width: 440px;
  width: 100%;
}

.hardware-card .mark-icon {
  width: 88px;
  height: 88px;
  color: var(--mark);
}

.pulse-strip {
  display: flex;
  align-items: center;
  gap: var(--space-12);
  background: var(--bg-sunken);
  border: 1px solid var(--line-hairline);
  padding: 8px 16px;
  border-radius: var(--radius-capsule);
  font-size: 0.8125rem;
  font-family: var(--font-mono);
  color: var(--text-secondary);
}

.pulse-strip .status-indicator {
  display: flex;
  align-items: center;
  gap: 6px;
  color: var(--status-ok);
  font-weight: 600;
}

/* Mark SVG styling */
.mark-svg {
  display: block;
  color: var(--mark);
}

.mark-svg .body {
  fill: none;
  stroke: currentColor;
  stroke-width: 7;
}

.mark-svg .pins {
  fill: none;
  stroke: currentColor;
  stroke-width: 6;
  stroke-linecap: round;
}

.mark-svg .core-bar {
  fill: currentColor;
}

.mark-svg .core-panel {
  fill: none;
  stroke: currentColor;
  stroke-width: 3.4;
}

/* Pillars Section */
.section {
  padding-top: var(--space-56);
  padding-bottom: var(--space-56);
}

.section-head {
  text-align: center;
  max-width: 640px;
  margin-left: auto;
  margin-right: auto;
  margin-bottom: var(--space-40);
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(290px, 1fr));
  gap: var(--space-24);
}

.card {
  background: var(--bg-surface);
  border: 1px solid var(--line-hairline);
  border-radius: var(--radius-card);
  padding: var(--space-24);
  display: flex;
  flex-direction: column;
  gap: var(--space-16);
  box-shadow: var(--shadow-sm);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.card:hover {
  box-shadow: var(--shadow-card);
}

.card-icon-wrap {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-chip);
  background: var(--accent-soft);
  color: var(--accent);
  display: grid;
  place-items: center;
}

.card-icon-wrap svg {
  width: 26px;
  height: 26px;
}

.card h3 {
  font-size: 1.25rem;
  margin: 0;
}

.card p {
  font-size: 0.9375rem;
  margin: 0;
  color: var(--text-secondary);
}

.feature-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: var(--space-8);
  font-size: 0.875rem;
  color: var(--text-secondary);
}

.feature-list li {
  display: flex;
  align-items: flex-start;
  gap: var(--space-8);
}

.feature-list li svg {
  width: 16px;
  height: 16px;
  color: var(--status-ok);
  flex-shrink: 0;
  margin-top: 2px;
}

/* Network Proof Section */
.proof-box {
  background: var(--bg-surface);
  border: 1px solid var(--line-hairline);
  border-radius: var(--radius-card);
  padding: var(--space-32);
  box-shadow: var(--shadow-card);
}

.proof-header {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  margin-bottom: var(--space-32);
}

.proof-number {
  font-family: var(--font-display);
  font-size: clamp(3.5rem, 8vw, 5.5rem);
  font-weight: 700;
  line-height: 1;
  color: var(--text-primary);
  margin-bottom: var(--space-8);
}

.proof-title {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--space-4);
}

.proof-sub {
  color: var(--text-secondary);
  font-size: 1rem;
  max-width: 520px;
}

.proof-ledger {
  background: var(--bg-sunken);
  border: 1px solid var(--line-hairline);
  border-radius: var(--radius-chip);
  overflow: hidden;
  margin-bottom: var(--space-20);
}

.ledger-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.875rem;
  text-align: left;
}

.ledger-table th,
.ledger-table td {
  padding: 12px 16px;
  border-bottom: 1px solid var(--line-hairline);
}

.ledger-table th {
  background: var(--bg-surface);
  color: var(--text-tertiary);
  font-weight: 600;
  text-transform: uppercase;
  font-size: 0.75rem;
  letter-spacing: 0.05em;
}

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

.ledger-table td:last-child {
  text-align: right;
  font-family: var(--font-mono);
}

.proof-disclosure {
  font-size: 0.8125rem;
  color: var(--text-tertiary);
  line-height: 1.5;
  border-top: 1px solid var(--line-hairline);
  padding-top: var(--space-16);
  margin-top: var(--space-16);
}

/* Pricing Section */
.pricing-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: var(--space-24);
  max-width: 840px;
  margin-left: auto;
  margin-right: auto;
}

.pricing-card {
  background: var(--bg-surface);
  border: 1px solid var(--line-hairline);
  border-radius: var(--radius-card);
  padding: var(--space-32);
  display: flex;
  flex-direction: column;
  position: relative;
  box-shadow: var(--shadow-sm);
}

.pricing-card.featured {
  border: 2px solid var(--accent);
  box-shadow: var(--shadow-card);
}

.pricing-card .card-badge {
  position: absolute;
  top: -12px;
  left: 50%;
  transform: translateX(-50%);
  background: var(--accent);
  color: var(--accent-on-accent);
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: 3px 12px;
  border-radius: var(--radius-capsule);
}

.price-box {
  margin: var(--space-16) 0 var(--space-20);
}

.price-amount {
  font-family: var(--font-display);
  font-size: 3rem;
  font-weight: 700;
  line-height: 1;
  color: var(--text-primary);
}

.price-period {
  font-size: 0.9375rem;
  color: var(--text-secondary);
  font-weight: 400;
  margin-left: var(--space-4);
}

.price-sub {
  font-size: 0.875rem;
  color: var(--text-tertiary);
  margin-top: var(--space-4);
}

.pricing-cta {
  margin: var(--space-24) 0;
}

.pricing-cta .btn {
  width: 100%;
}

.pricing-note {
  font-size: 0.8125rem;
  color: var(--text-tertiary);
  text-align: center;
  margin: 0;
}

/* FAQ Accordion */
.faq-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-12);
  max-width: 760px;
  margin-left: auto;
  margin-right: auto;
}

.faq-item {
  background: var(--bg-surface);
  border: 1px solid var(--line-hairline);
  border-radius: var(--radius-chip);
  overflow: hidden;
  transition: border-color 0.15s ease;
}

.faq-item[open] {
  border-color: var(--line-strong);
}

.faq-question {
  padding: var(--space-16) var(--space-20);
  font-weight: 600;
  font-size: 1.0625rem;
  color: var(--text-primary);
  cursor: pointer;
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  user-select: none;
}

.faq-question::-webkit-details-marker {
  display: none;
}

.faq-question::after {
  content: "+";
  font-size: 1.25rem;
  font-weight: 400;
  color: var(--text-secondary);
  transition: transform 0.2s ease;
  line-height: 1;
}

.faq-item[open] .faq-question::after {
  content: "−";
}

.faq-answer {
  padding: 0 var(--space-20) var(--space-20);
  color: var(--text-secondary);
  font-size: 0.9375rem;
  line-height: 1.6;
}

.faq-answer p:last-child {
  margin-bottom: 0;
}

/* Article / Sub-page Layout */
.page-header {
  padding-top: var(--space-40);
  padding-bottom: var(--space-32);
  border-bottom: 1px solid var(--line-hairline);
  margin-bottom: var(--space-40);
}

.page-header h1 {
  margin-bottom: var(--space-8);
}

.article-content section {
  margin-bottom: var(--space-40);
}

.callout {
  background: var(--bg-sunken);
  border: 1px solid var(--line-hairline);
  border-left: 4px solid var(--accent);
  border-radius: var(--radius-chip);
  padding: var(--space-16) var(--space-20);
  margin: var(--space-20) 0;
}

.callout p:last-child {
  margin-bottom: 0;
}

.code-card {
  background: var(--bg-sunken);
  border: 1px solid var(--line-hairline);
  border-radius: var(--radius-chip);
  padding: var(--space-16);
  margin: var(--space-16) 0;
  overflow-x: auto;
}

.code-card pre {
  margin: 0;
  font-size: 0.875rem;
}

/* Footer */
.site-footer {
  margin-top: auto;
  border-top: 1px solid var(--line-hairline);
  background-color: var(--bg-surface);
  padding: var(--space-40) 0 var(--space-32);
  font-size: 0.875rem;
  color: var(--text-secondary);
}

.footer-grid {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  flex-wrap: wrap;
  gap: var(--space-32);
  margin-bottom: var(--space-32);
}

.footer-brand {
  max-width: 300px;
}

.footer-brand p {
  font-size: 0.875rem;
  margin-top: var(--space-8);
}

.footer-nav {
  display: flex;
  gap: var(--space-40);
  flex-wrap: wrap;
}

.footer-col {
  display: flex;
  flex-direction: column;
  gap: var(--space-10);
}

.footer-col-title {
  font-weight: 600;
  color: var(--text-primary);
  font-size: 0.8125rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: var(--space-4);
}

.footer-col a {
  color: var(--text-secondary);
  text-decoration: none;
}

.footer-col a:hover {
  color: var(--text-primary);
  text-decoration: underline;
}

.footer-bottom {
  border-top: 1px solid var(--line-hairline);
  padding-top: var(--space-20);
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--space-12);
  font-size: 0.8125rem;
  color: var(--text-tertiary);
}

/* Mobile Responsiveness */
@media (max-width: 768px) {
  .nav-links {
    display: none; /* simple, clean mobile view */
  }

  .hero {
    padding-top: var(--space-32);
    padding-bottom: var(--space-40);
  }

  .proof-box {
    padding: var(--space-20);
  }

  .footer-grid {
    flex-direction: column;
    gap: var(--space-24);
  }

  .footer-bottom {
    flex-direction: column;
    align-items: flex-start;
  }
}

/* Download + licence pages (WEB-03, COM-10) */
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }
.dl-grid { display: grid; gap: var(--space-24); grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); margin-bottom: var(--space-24); }
.spec { display: grid; grid-template-columns: max-content 1fr; gap: var(--space-8) var(--space-16); margin: var(--space-16) 0; }
.spec dt { color: var(--text-secondary); }
.spec dd { margin: 0; min-width: 0; }
.hash { font-family: var(--font-mono); font-size: 0.8rem; overflow-wrap: anywhere; }
.steps { padding-left: 20px; color: var(--text-secondary); line-height: 1.7; }
.lic-form { display: grid; gap: var(--space-12); max-width: 460px; }
.lic-form label { font-weight: 600; }
.lic-form .check { font-weight: 400; display: flex; gap: var(--space-8); align-items: center; }
.lic-form input[type=email] { font: inherit; padding: 12px 14px; border-radius: var(--radius-chip); border: 1px solid var(--line-strong); background: var(--bg-surface); color: var(--text-primary); }
.lic-form input:focus-visible, .lic-result a:focus-visible, .lic-result button:focus-visible { outline: 3px solid var(--accent); outline-offset: 2px; }
.lic-form input[type=checkbox] { width: 18px; height: 18px; accent-color: var(--accent); }
.hint { color: var(--text-secondary); font-size: 0.9rem; margin: 0; }
.lic-status { min-height: 1.6em; margin: var(--space-12) 0; }
.lic-status.err { color: var(--status-bad); font-weight: 600; }
.lic-result[hidden] { display: none; }
.lic-key { display: block; font-family: var(--font-mono); background: var(--bg-sunken); border: 1px solid var(--line-hairline); border-radius: var(--radius-chip); padding: var(--space-16); overflow-wrap: anywhere; user-select: all; max-height: 11em; overflow: auto; }
.lic-actions { display: flex; flex-wrap: wrap; gap: var(--space-12); margin: var(--space-16) 0; }