/* ============================================================
   METROLOGIST — Precision Instrument Design System
   Palette: survey-field dark · staff red/white · amber readout
   Fonts: DM Mono (display) · Crimson Pro (body) · Vazirmatn (Persian)
   ============================================================ */

@import url('https://fonts.googleapis.com/css2?family=DM+Mono:ital,wght@0,300;0,400;0,500;1,300&family=Crimson+Pro:ital,wght@0,300;0,400;0,600;1,300;1,400&family=Vazirmatn:wght@300;400;500;700&display=swap');

/* ── Design tokens ── */
:root {
  --bg-deep:       #0D0F0E;
  --bg-surface:    #141714;
  --bg-card:       #1C1F1C;
  --bg-card-hover: #222622;

  --staff-red:     #D42B2B;
  --staff-white:   #F2F2EE;

  --amber:         #E8A020;
  --amber-dim:     #9B6A14;
  --amber-glow:    rgba(232, 160, 32, 0.35);

  --green-read:    #55C98A;
  --green-dim:     rgba(61, 170, 107, 0.15);

  --grid-line:     rgba(242, 242, 238, 0.055);
  --grid-line-2:   rgba(242, 242, 238, 0.02);

  --text-primary:  #F2F2EE;
  --text-secondary:#8A9189;
  --text-dim:      #4A524A;

  --rail-width:    6px;
  --rail-band:     28px;

  --radius-sm:     4px;
  --radius:        6px;

  --transition:    0.22s cubic-bezier(0.4, 0, 0.2, 1);
}

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

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

body {
  background-color: var(--bg-deep);
  color: var(--text-primary);
  font-family: 'Crimson Pro', Georgia, serif;
  font-size: 1.0625rem;
  line-height: 1.65;
  /* Engineering grid background */
  background-image:
    linear-gradient(var(--grid-line) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid-line) 1px, transparent 1px),
    linear-gradient(var(--grid-line-2) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid-line-2) 1px, transparent 1px);
  background-size: 120px 120px, 120px 120px, 24px 24px, 24px 24px;
  background-position: -1px -1px, -1px -1px, -1px -1px, -1px -1px;
  min-height: 100vh;
  overflow-x: hidden;
  position: relative;
}

[dir="rtl"] body {
  font-family: 'Vazirmatn', 'Crimson Pro', Georgia, serif;
}

/* ── Noise grain overlay ── */
body::after {
  content: '';
  position: fixed;
  inset: 0;
  pointer-events: none;
  opacity: 0.028;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
  background-size: 256px 256px;
  z-index: 9999;
}

/* ── Staff rail (fixed left edge) ── */
.staff-rail {
  position: fixed;
  top: 0;
  left: 0;
  width: var(--rail-width);
  height: 100vh;
  z-index: 100;
  background: repeating-linear-gradient(
    to bottom,
    var(--staff-red)   0px,
    var(--staff-red)   var(--rail-band),
    var(--staff-white) var(--rail-band),
    var(--staff-white) calc(var(--rail-band) * 2)
  );
  box-shadow: 2px 0 12px rgba(212, 43, 43, 0.25);
}

[dir="rtl"] .staff-rail {
  left: auto;
  right: 0;
  box-shadow: -2px 0 12px rgba(212, 43, 43, 0.25);
}

/* ── Page wrapper ── */
.page-wrap {
  padding-left: calc(var(--rail-width) + 16px);
  padding-right: 16px;
  max-width: 1200px;
  margin: 0 auto;
}

[dir="rtl"] .page-wrap {
  padding-left: 16px;
  padding-right: calc(var(--rail-width) + 16px);
}

/* ── Utility: DM Mono text ── */
.mono { font-family: 'DM Mono', 'Courier New', monospace; }

/* ── Nav ── */
.site-nav {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(13, 15, 14, 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--grid-line);
}

.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.75rem 1rem 0.75rem calc(var(--rail-width) + 16px);
  gap: 1rem;
}

[dir="rtl"] .nav-inner {
  padding: 0.75rem calc(var(--rail-width) + 16px) 0.75rem 1rem;
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: 0.55rem;
  text-decoration: none;
  color: var(--text-primary);
}

.nav-brand-icon {
  width: 28px;
  height: 28px;
  flex-shrink: 0;
}

.nav-brand-name {
  font-family: 'DM Mono', monospace;
  font-size: 0.9rem;
  font-weight: 500;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.lang-switch {
  font-family: 'DM Mono', monospace;
  font-size: 0.72rem;
  letter-spacing: 0.05em;
  color: var(--text-secondary);
  text-decoration: none;
  padding: 0.35rem 0.65rem;
  border: 1px solid var(--text-secondary);
  border-radius: var(--radius-sm);
  transition: color var(--transition), border-color var(--transition);
  height: 2.75rem;
  display: flex;
  align-items: center;
}

.lang-switch:hover {
  color: var(--amber);
  border-color: var(--amber);
}

/* ── Section layout ── */
section {
  padding: 3.5rem 0;
}

.section-label {
  font-family: 'DM Mono', monospace;
  font-size: 0.68rem;
  font-weight: 500;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--amber);
  margin-bottom: 0.75rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.section-label::before {
  content: '';
  display: inline-block;
  width: 18px;
  height: 2px;
  background: var(--amber);
  flex-shrink: 0;
}

[dir="rtl"] .section-label {
  flex-direction: row-reverse;
}

/* ── Hero ── */
.hero {
  padding: 4rem 0 3rem;
  position: relative;
  min-height: 70vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.hero-readout {
  font-family: 'DM Mono', monospace;
  font-size: clamp(4rem, 20vw, 9rem);
  font-weight: 300;
  line-height: 0.9;
  color: var(--amber);
  text-shadow: 0 0 40px var(--amber-glow), 0 0 80px rgba(232, 160, 32, 0.1);
  position: absolute;
  top: 2.5rem;
  right: 1rem;
  opacity: 0.22;
  letter-spacing: -0.02em;
  pointer-events: none;
  user-select: none;
}

[dir="rtl"] .hero-readout {
  right: auto;
  left: 1rem;
}

.hero-content {
  position: relative;
  z-index: 1;
  max-width: 600px;
}

.hero-eyebrow {
  font-family: 'DM Mono', monospace;
  font-size: 0.7rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--text-secondary);
  margin-bottom: 1.25rem;
  animation: fadeUp 0.6s ease both;
  animation-delay: 0.05s;
}

.hero h1 {
  font-family: 'Crimson Pro', Georgia, serif;
  font-size: clamp(2.2rem, 7vw, 3.6rem);
  font-weight: 300;
  line-height: 1.12;
  letter-spacing: -0.01em;
  margin-bottom: 1.25rem;
  animation: fadeUp 0.6s ease both;
  animation-delay: 0.12s;
}

[dir="rtl"] .hero h1 {
  font-family: 'Vazirmatn', serif;
  font-weight: 300;
}

.hero h1 em {
  font-style: normal;
  color: var(--amber);
}

.hero-desc {
  font-size: 1.1rem;
  color: var(--text-secondary);
  max-width: 480px;
  line-height: 1.7;
  margin-bottom: 2rem;
  animation: fadeUp 0.6s ease both;
  animation-delay: 0.2s;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  animation: fadeUp 0.6s ease both;
  animation-delay: 0.28s;
}

/* ── Buttons ── */
.btn-primary {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: var(--staff-red);
  color: var(--staff-white);
  text-decoration: none;
  font-family: 'DM Mono', monospace;
  font-size: 0.82rem;
  font-weight: 500;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  padding: 0.8rem 1.4rem;
  border-radius: var(--radius-sm);
  min-height: 48px;
  transition: background var(--transition), box-shadow var(--transition), transform var(--transition);
  border: none;
  cursor: pointer;
}

.btn-primary:hover {
  background: #e8322e;
  box-shadow: 0 0 24px rgba(212, 43, 43, 0.45);
  transform: translateY(-1px);
}

.btn-secondary {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: transparent;
  color: var(--text-secondary);
  text-decoration: none;
  font-family: 'DM Mono', monospace;
  font-size: 0.82rem;
  font-weight: 400;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  padding: 0.8rem 1.4rem;
  border-radius: var(--radius-sm);
  border: 1px solid var(--text-dim);
  min-height: 48px;
  transition: color var(--transition), border-color var(--transition), transform var(--transition);
  cursor: pointer;
}

.btn-secondary:hover {
  color: var(--text-primary);
  border-color: var(--text-secondary);
  transform: translateY(-1px);
}

.btn-tertiary {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  background: transparent;
  color: var(--text-secondary);
  text-decoration: none;
  font-family: 'DM Mono', monospace;
  font-size: 0.78rem;
  font-weight: 400;
  letter-spacing: 0.05em;
  padding: 0.5rem 0.25rem;
  border: none;
  min-height: 44px;
  transition: color var(--transition);
  cursor: pointer;
  text-underline-offset: 3px;
}

.btn-tertiary:hover {
  color: var(--text-primary);
  text-decoration: underline;
}

/* ── h2 default ── */
h2 {
  font-family: 'Crimson Pro', Georgia, serif;
  font-size: clamp(1.4rem, 4vw, 1.75rem);
  font-weight: 300;
  line-height: 1.18;
  letter-spacing: -0.01em;
  color: var(--text-primary);
  margin-bottom: 1rem;
}

/* ── Staff band divider ── */
.staff-divider {
  height: 8px;
  width: 100%;
  background: repeating-linear-gradient(
    to right,
    var(--staff-red)   0px,
    var(--staff-red)   32px,
    var(--staff-white) 32px,
    var(--staff-white) 64px
  );
  opacity: 0.18;
  margin: 0;
}

/* ── How-it-works ── */
.steps-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.5rem;
  margin-top: 2rem;
}

.step-card {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 1.75rem 1.5rem 1.5rem;
  position: relative;
  transition: background var(--transition), transform var(--transition);
}

.step-card::before,
.step-card::after {
  content: '';
  position: absolute;
  width: 14px;
  height: 14px;
  border-color: var(--amber-dim);
  border-style: solid;
  transition: border-color var(--transition);
}

.step-card::before {
  top: 8px; left: 8px;
  border-width: 1.5px 0 0 1.5px;
}

.step-card::after {
  bottom: 8px; right: 8px;
  border-width: 0 1.5px 1.5px 0;
}

[dir="rtl"] .step-card::before {
  left: auto; right: 8px;
  border-width: 1.5px 1.5px 0 0;
}

[dir="rtl"] .step-card::after {
  right: auto; left: 8px;
  border-width: 0 0 1.5px 1.5px;
}

.step-card:hover {
  background: var(--bg-card-hover);
  transform: translateY(-2px);
}

.step-card:hover::before,
.step-card:hover::after {
  border-color: var(--amber);
}

.step-num {
  font-family: 'DM Mono', monospace;
  font-size: 0.68rem;
  letter-spacing: 0.15em;
  color: var(--amber);
  margin-bottom: 0.6rem;
  display: block;
}

.step-card h3 {
  font-family: 'DM Mono', monospace;
  font-size: 0.88rem;
  font-weight: 500;
  letter-spacing: 0.04em;
  color: var(--text-primary);
  margin-bottom: 0.6rem;
}

[dir="rtl"] .step-card h3 {
  font-family: 'Vazirmatn', sans-serif;
  letter-spacing: 0;
}

.step-card p {
  font-size: 0.97rem;
  color: var(--text-secondary);
  line-height: 1.62;
}

/* ── Features ── */
.features-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
  margin-top: 2rem;
}

.feature-item {
  display: flex;
  gap: 1rem;
  align-items: flex-start;
  padding: 1.25rem;
  background: var(--bg-card);
  border-radius: var(--radius);
  border-left: 3px solid var(--bg-card);
  transition: border-color var(--transition), background var(--transition);
}

[dir="rtl"] .feature-item {
  border-left: none;
  border-right: 3px solid var(--bg-card);
  flex-direction: row-reverse;
}

.feature-item:hover {
  border-left-color: var(--staff-red);
  background: var(--bg-card-hover);
}

[dir="rtl"] .feature-item:hover {
  border-right-color: var(--staff-red);
  border-left-color: transparent;
}

.feature-icon {
  flex-shrink: 0;
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--amber);
}

.feature-icon svg {
  width: 20px;
  height: 20px;
}

.feature-text h3 {
  font-family: 'DM Mono', monospace;
  font-size: 0.82rem;
  font-weight: 500;
  letter-spacing: 0.04em;
  color: var(--text-primary);
  margin-bottom: 0.3rem;
}

[dir="rtl"] .feature-text h3 {
  font-family: 'Vazirmatn', sans-serif;
  letter-spacing: 0;
}

.feature-text p {
  font-size: 0.93rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

/* ── Accuracy callout ── */
.accuracy-block {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 2rem 1.5rem;
  margin-top: 2rem;
  position: relative;
  overflow: hidden;
}

.accuracy-block::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 2px;
  background: repeating-linear-gradient(
    to right,
    var(--staff-red) 0, var(--staff-red) 16px,
    var(--staff-white) 16px, var(--staff-white) 32px
  );
  opacity: 0.5;
}

[dir="rtl"] .accuracy-block::before {
  background: repeating-linear-gradient(
    to left,
    var(--staff-red) 0, var(--staff-red) 16px,
    var(--staff-white) 16px, var(--staff-white) 32px
  );
}

.accuracy-readout {
  font-family: 'DM Mono', monospace;
  font-size: clamp(2.4rem, 10vw, 4.2rem);
  font-weight: 300;
  color: var(--amber);
  text-shadow: 0 0 30px var(--amber-glow);
  line-height: 1;
  margin-bottom: 0.5rem;
}

.accuracy-label {
  font-family: 'DM Mono', monospace;
  font-size: 0.72rem;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--text-secondary);
  margin-bottom: 1rem;
}

.accuracy-block p {
  color: var(--text-secondary);
  font-size: 0.97rem;
  max-width: 560px;
}

/* ── Confidence meter ── */
.confidence-row {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-top: 1.25rem;
}

.confidence-bar-wrap {
  flex: 1;
  height: 6px;
  background: var(--bg-deep);
  border-radius: 3px;
  overflow: hidden;
  max-width: 200px;
}

.confidence-bar {
  height: 100%;
  width: 92%;
  background: linear-gradient(to right, var(--green-read), #5DBCA3);
  border-radius: 3px;
  box-shadow: 0 0 8px rgba(61, 170, 107, 0.5);
}

.confidence-value {
  font-family: 'DM Mono', monospace;
  font-size: 0.78rem;
  color: var(--green-read);
  letter-spacing: 0.05em;
}

/* ── Open source ── */
.opensource-block {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 1.75rem 1.5rem;
  margin-top: 2rem;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.license-badge {
  font-family: 'DM Mono', monospace;
  font-size: 0.72rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--green-read);
  background: var(--green-dim);
  border: 1px solid rgba(61, 170, 107, 0.3);
  border-radius: var(--radius-sm);
  padding: 0.3rem 0.65rem;
  display: inline-block;
  width: fit-content;
}

.opensource-block p {
  color: var(--text-secondary);
  font-size: 0.97rem;
}

.opensource-block a {
  color: var(--amber);
  text-decoration: none;
  transition: color var(--transition);
}

.opensource-block a:hover {
  color: var(--staff-white);
}

/* ── Footer ── */
.site-footer {
  border-top: 1px solid var(--grid-line);
  padding: 2rem 0 2.5rem;
  margin-top: 1rem;
}

.footer-inner {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.footer-copy {
  font-family: 'DM Mono', monospace;
  font-size: 0.72rem;
  letter-spacing: 0.06em;
  color: var(--text-secondary);
  line-height: 1.7;
}

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

.footer-copy a:hover {
  color: var(--amber);
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
}

.footer-links a {
  font-family: 'DM Mono', monospace;
  font-size: 0.72rem;
  letter-spacing: 0.08em;
  color: var(--text-secondary);
  text-decoration: none;
  transition: color var(--transition);
}

.footer-links a:hover {
  color: var(--text-secondary);
}

/* ── Animations ── */
@keyframes fadeUp {
  from {
    opacity: 0;
    transform: translateY(18px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.reveal {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 0.55s ease, transform 0.55s ease;
}

.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ── Reduced motion ── */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: .01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .01ms !important;
  }
  html { scroll-behavior: auto; }
  .reveal { opacity: 1; transform: none; }
}

/* ── Crosshair hero decoration ── */
.hero-crosshair {
  position: absolute;
  top: 50%;
  right: 8%;
  transform: translateY(-50%);
  width: 120px;
  height: 120px;
  opacity: 0.07;
  pointer-events: none;
}

[dir="rtl"] .hero-crosshair {
  right: auto;
  left: 8%;
}

/* ── Responsive: 640px ── */
@media (min-width: 640px) {
  .page-wrap {
    padding-left: calc(var(--rail-width) + 28px);
    padding-right: 28px;
  }
  [dir="rtl"] .page-wrap {
    padding-left: 28px;
    padding-right: calc(var(--rail-width) + 28px);
  }
  .nav-inner {
    padding-left: calc(var(--rail-width) + 28px);
    padding-right: 28px;
  }
  [dir="rtl"] .nav-inner {
    padding-left: 28px;
    padding-right: calc(var(--rail-width) + 28px);
  }
  .steps-grid {
    grid-template-columns: 1fr 1fr;
  }
  .features-grid {
    grid-template-columns: 1fr 1fr;
  }
  .footer-inner {
    flex-direction: row;
    align-items: center;
    justify-content: space-between;
  }
}

/* ── Responsive: 768px ── */
@media (min-width: 768px) {
  :root { --rail-width: 8px; --rail-band: 32px; }

  .page-wrap {
    padding-left: calc(var(--rail-width) + 40px);
    padding-right: 40px;
  }
  [dir="rtl"] .page-wrap {
    padding-left: 40px;
    padding-right: calc(var(--rail-width) + 40px);
  }
  .nav-inner {
    padding-left: calc(var(--rail-width) + 40px);
    padding-right: 40px;
  }
  [dir="rtl"] .nav-inner {
    padding-left: 40px;
    padding-right: calc(var(--rail-width) + 40px);
  }
  .hero {
    min-height: 80vh;
  }
  .steps-grid {
    grid-template-columns: repeat(3, 1fr);
  }
  .hero-crosshair {
    width: 160px;
    height: 160px;
  }
}

/* ── Responsive: 1024px ── */
@media (min-width: 1024px) {
  .page-wrap {
    padding-left: calc(var(--rail-width) + 60px);
    padding-right: 60px;
  }
  [dir="rtl"] .page-wrap {
    padding-left: 60px;
    padding-right: calc(var(--rail-width) + 60px);
  }
  .nav-inner {
    padding-left: calc(var(--rail-width) + 60px);
    padding-right: 60px;
  }
  [dir="rtl"] .nav-inner {
    padding-left: 60px;
    padding-right: calc(var(--rail-width) + 60px);
  }
  .features-grid {
    grid-template-columns: repeat(3, 1fr);
  }
  .accuracy-block {
    display: flex;
    align-items: flex-start;
    gap: 3rem;
  }
  .accuracy-left {
    flex-shrink: 0;
    min-width: 160px;
  }
  .hero-readout {
    opacity: 0.18;
  }
}

/* ── Focus styles ── */
a:focus-visible,
button:focus-visible {
  outline: 2px solid var(--amber);
  outline-offset: 3px;
  border-radius: 2px;
}

/* ── Skip link ── */
.skip-link {
  position: absolute;
  top: -100%;
  left: 0;
  background: var(--amber);
  color: var(--bg-deep);
  padding: 0.5rem 1rem;
  font-family: 'DM Mono', monospace;
  font-size: 0.8rem;
  z-index: 9999;
  text-decoration: none;
}

.skip-link:focus {
  top: 0;
}