/* ============================================================
   ARP17 landing page
   Palette:
     paper       #F5F7F6  cool white
     grid        #E3E9E7  graph-paper lines
     ink         #14262B  deep slate-teal
     ink-soft    #435A60  secondary text
     ultramarine #2036C4  single accent
     node-fill   #FFFFFF  diagram nodes
   Type:
     display  Bricolage Grotesque
     body     Archivo
     utility  IBM Plex Mono
   ============================================================ */

:root {
  --paper: #F5F7F6;
  --grid: #E3E9E7;
  --ink: #14262B;
  --ink-soft: #435A60;
  --accent: #2036C4;
  --node-fill: #FFFFFF;
  --font-display: "Bricolage Grotesque", "Archivo", sans-serif;
  --font-body: "Archivo", -apple-system, "Segoe UI", sans-serif;
  --font-mono: "IBM Plex Mono", ui-monospace, "SF Mono", monospace;
  --measure: 38rem;
  --gutter: clamp(1.25rem, 5vw, 4rem);
  interpolate-size: allow-keywords;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-body);
  font-size: 1.0625rem;
  line-height: 1.6;
  color: var(--ink);
  background-color: var(--paper);
  background-image:
    linear-gradient(var(--grid) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid) 1px, transparent 1px);
  background-size: 36px 36px;
  -webkit-font-smoothing: antialiased;
}

/* ---------- Focus and skip link ---------- */

:focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: 3px;
  border-radius: 2px;
}

.skip-link {
  position: absolute;
  left: 1rem;
  top: -4rem;
  z-index: 10;
  padding: 0.75rem 1.25rem;
  background: var(--ink);
  color: var(--paper);
  font-family: var(--font-mono);
  font-size: 0.875rem;
  text-decoration: none;
  transition: top 0.15s ease-out;
}

.skip-link:focus {
  top: 1rem;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
}

/* ---------- Header ---------- */

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem 1.5rem;
  padding: 1.1rem var(--gutter);
  border-bottom: 1px solid var(--ink);
  background: var(--paper);
}

.wordmark {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  min-height: 44px;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 1.35rem;
  letter-spacing: 0.02em;
  color: var(--ink);
  text-decoration: none;
}

.wordmark-loop {
  width: 1.25rem;
  height: 1.25rem;
  color: var(--accent);
}

.site-nav {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.25rem 0.5rem;
  list-style: none;
}

.site-nav a {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding: 0.25rem 0.75rem;
  font-family: var(--font-mono);
  font-size: 0.875rem;
  color: var(--ink);
  text-decoration: none;
}

.site-nav a:hover {
  color: var(--accent);
  text-decoration: underline;
  text-underline-offset: 0.35em;
}

.site-nav a.active {
  color: var(--accent);
  text-decoration: underline;
  text-decoration-color: var(--accent);
  text-underline-offset: 0.35em;
}

.nav-external-arrow {
  margin-left: 0.4em;
  transform: translateY(-0.05em);
  transition: transform 0.15s ease;
}

.site-nav a.nav-external:hover .nav-external-arrow {
  transform: translate(0.1em, -0.15em);
}

.site-nav .nav-cta {
  border: 1.5px solid var(--ink);
  border-radius: 999px;
  padding: 0.25rem 1.1rem;
}

.site-nav .nav-cta:hover {
  background: var(--ink);
  color: var(--paper);
  text-decoration: none;
}

.site-nav .nav-cta.active {
  border-color: var(--accent);
  color: var(--accent);
  text-decoration: none;
}

/* Language switcher */

.nav-lang {
  display: inline-flex;
  align-items: center;
}

.nav-lang-rule {
  width: 1px;
  height: 1.1rem;
  margin-inline: 0.35rem 0.15rem;
  background: var(--ink);
  opacity: 0.3;
}

.site-nav .nav-lang a {
  padding: 0.25rem 0.45rem;
  font-size: 0.8125rem;
}

.site-nav .nav-lang a[aria-current="page"] {
  color: var(--accent);
  text-decoration: underline;
  text-underline-offset: 0.35em;
}

/* Hamburger toggle (mobile only) */

.nav-toggle {
  display: none;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  border: none;
  background: none;
  cursor: pointer;
  color: var(--ink);
}

.nav-toggle-box {
  position: relative;
  display: block;
  width: 26px;
  height: 18px;
}

.nav-toggle-bar {
  position: absolute;
  left: 0;
  width: 100%;
  height: 2.5px;
  border-radius: 2px;
  background: currentColor;
  transition: transform 0.25s ease, opacity 0.2s ease;
}

.nav-toggle-bar:nth-child(1) { top: 0; }
.nav-toggle-bar:nth-child(2) { top: 50%; transform: translateY(-50%); }
.nav-toggle-bar:nth-child(3) { bottom: 0; }

.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(1) {
  top: 50%;
  transform: translateY(-50%) rotate(45deg);
}

.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(2) {
  opacity: 0;
}

.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(3) {
  bottom: auto;
  top: 50%;
  transform: translateY(-50%) rotate(-45deg);
}

@media (max-width: 47.99rem) {
  .site-header {
    padding-block: 0.6rem;
  }

  .site-header nav {
    display: contents;
  }

  .nav-toggle {
    display: inline-flex;
    justify-content: flex-end;
    position: relative;
    z-index: 95;
  }

  .wordmark {
    position: relative;
    z-index: 95;
  }

  .site-nav {
    position: fixed;
    inset: 0;
    z-index: 90;
    flex-direction: column;
    flex-wrap: nowrap;
    align-items: flex-start;
    justify-content: flex-start;
    gap: 0.25rem;
    padding: 5.5rem var(--gutter) 2rem;
    background-color: var(--paper);
    background-image:
      linear-gradient(var(--grid) 1px, transparent 1px),
      linear-gradient(90deg, var(--grid) 1px, transparent 1px);
    background-size: 36px 36px;
    overflow-y: auto;
    transform: translateX(100%);
    visibility: hidden;
    transition: transform 0.25s ease, visibility 0.25s;
  }

  body.nav-open {
    overflow: hidden;
  }

  body.nav-open .site-nav {
    transform: translateX(0);
    visibility: visible;
  }

  .site-nav li {
    display: flex;
    justify-content: flex-end;
    width: 100%;
  }

  .site-nav a {
    justify-content: flex-end;
    width: 100%;
    min-height: 52px;
    padding: 0.5rem 0;
    font-size: 1.25rem;
    text-align: right;
  }

  .site-nav .nav-cta {
    display: inline-flex;
    width: auto;
    margin-top: 0.75rem;
    padding: 0.5rem 1.5rem;
  }

  .site-nav .nav-lang {
    justify-content: flex-end;
    gap: 0.5rem;
    margin-top: 1.25rem;
  }

  .nav-lang-rule {
    display: none;
  }

  .site-nav .nav-lang a {
    width: auto;
    font-size: 1.1rem;
  }
}

/* ---------- Shared section shell ---------- */

.section,
.hero {
  padding: clamp(3.5rem, 9vw, 7rem) var(--gutter);
  max-width: 74rem;
  margin-inline: auto;
  scroll-margin-top: 5.5rem;
}

.eyebrow {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  font-weight: 500;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 1.1rem;
}

.version {
  display: inline-block;
  margin-right: 0.6rem;
  padding: 0.1rem 0.5rem;
  border: 1.5px solid currentColor;
  border-radius: 4px;
  text-transform: none;
}

h1, h2, h3 {
  font-family: var(--font-display);
  font-weight: 800;
  line-height: 1.08;
  letter-spacing: -0.015em;
  text-wrap: balance;
}

h1 {
  font-size: clamp(2.4rem, 6.5vw, 4.4rem);
  max-width: 16ch;
}

h2 {
  font-size: clamp(1.85rem, 4.5vw, 3rem);
  max-width: 22ch;
}

h3 {
  font-size: 1.25rem;
  font-weight: 600;
}

.lede,
.section-lede {
  max-width: var(--measure);
  margin-top: 1.25rem;
  font-size: clamp(1.0625rem, 1.8vw, 1.2rem);
  color: var(--ink-soft);
}

/* ---------- Buttons ---------- */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  padding: 0.6rem 1.6rem;
  border-radius: 999px;
  font-family: var(--font-mono);
  font-size: 0.95rem;
  font-weight: 500;
  text-decoration: none;
  transition: transform 0.12s ease-out, background-color 0.12s ease-out, color 0.12s ease-out;
}

.btn:hover {
  transform: translateY(-2px);
}

button.btn {
  background: none;
  cursor: pointer;
}

.btn-primary {
  background: var(--accent);
  color: #FFFFFF;
  border: 1.5px solid var(--accent);
}

.btn-primary:hover {
  background: #1729A3;
}

.btn-ghost {
  border: 1.5px solid var(--ink);
  color: var(--ink);
}

.btn-ghost:hover {
  background: var(--ink);
  color: var(--paper);
}

.btn-invert {
  background: var(--paper);
  color: var(--ink);
  border: 1.5px solid var(--paper);
  max-width: 100%;
  overflow-wrap: anywhere;
  text-align: center;
}

.btn-invert:hover {
  background: #FFFFFF;
}

/* ---------- Hero ---------- */

.hero {
  display: grid;
  grid-template-columns: 1fr;
  gap: 3rem;
  align-items: center;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 2.25rem;
}

.hero-figure {
  display: flex;
  justify-content: center;
}

.loop-diagram {
  width: min(100%, 26rem);
  height: auto;
}

/* Loop diagram parts */

.loop-dash {
  fill: none;
  stroke: var(--accent);
  stroke-opacity: 0.35;
  stroke-width: 2;
  stroke-dasharray: 3 10;
  stroke-linecap: round;
  transform-origin: 220px 220px;
  animation: loop-spin 48s linear infinite;
}

@keyframes loop-spin {
  to { transform: rotate(360deg); }
}

.loop-arrows path {
  fill: none;
  stroke: var(--accent);
  stroke-width: 3;
  stroke-linecap: round;
}

.loop-arrowhead {
  fill: var(--accent);
}

.loop-node circle {
  fill: var(--node-fill);
  stroke: var(--ink);
  stroke-width: 2.5;
}

.loop-node text {
  font-family: var(--font-display);
  font-size: 38px;
  font-weight: 800;
  fill: var(--ink);
  text-anchor: middle;
  dominant-baseline: central;
}

.loop-labels text {
  font-family: var(--font-mono);
  font-size: 15px;
  letter-spacing: 0.06em;
  fill: var(--ink-soft);
  text-anchor: middle;
}

.loop-center {
  font-family: var(--font-mono);
  font-size: 22px;
  font-weight: 500;
  fill: var(--accent);
  text-anchor: middle;
  dominant-baseline: central;
}

/* ---------- v0.1 Cycle cards ---------- */

.cycle-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
  margin-top: 3rem;
}

.cycle-card {
  padding: 1.75rem 1.5rem;
  border: 1.5px solid var(--ink);
  border-radius: 10px;
  background: var(--paper);
}

.cycle-card h3 {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 0.85rem;
}

.cycle-letter {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2.4rem;
  height: 2.4rem;
  flex-shrink: 0;
  border: 2px solid var(--ink);
  border-radius: 50%;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 1.15rem;
  background: var(--node-fill);
}

.cycle-card p {
  color: var(--ink-soft);
}

.cycle-card-repeat {
  background: var(--ink);
  border-color: var(--ink);
  color: var(--paper);
}

.cycle-card-repeat .cycle-letter {
  background: var(--ink);
  border-color: var(--paper);
  color: var(--paper);
}

.cycle-card-repeat p {
  color: #C6D4D2;
}

/* ---------- v0.2 Services ---------- */

.services-list {
  display: grid;
  grid-template-columns: 1fr;
  gap: 2rem 3rem;
  margin-top: 3rem;
}

.service {
  border-top: 1.5px solid var(--ink);
  padding-top: 1.1rem;
}

.service dt {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1.15rem;
  margin-bottom: 0.4rem;
}

.service dd {
  color: var(--ink-soft);
}

/* ---------- v0.3 Engagement ---------- */

.engagement-steps {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
  margin-top: 3rem;
  list-style: none;
  counter-reset: none;
}

.step {
  padding: 1.75rem 1.5rem;
  border: 1.5px dashed var(--ink-soft);
  border-radius: 10px;
}

.step-when {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  font-weight: 500;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 0.75rem;
}

.step h3 {
  margin-bottom: 0.6rem;
}

.step p:last-child {
  color: var(--ink-soft);
}

/* ---------- v0.4 Data privacy ---------- */

.privacy-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
  margin-top: 3rem;
}

.privacy-card {
  padding: 1.75rem 1.5rem;
  border: 1.5px dashed var(--ink-soft);
  border-radius: 10px;
}

.privacy-tag {
  display: inline-block;
  margin-bottom: 0.9rem;
  padding: 0.1rem 0.5rem;
  border: 1.5px dashed var(--accent);
  border-radius: 4px;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  font-weight: 500;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent);
}

.privacy-card h3 {
  margin-bottom: 0.6rem;
}

.privacy-card p:last-child {
  color: var(--ink-soft);
}

.privacy-note {
  max-width: var(--measure);
  margin-top: 2rem;
  font-family: var(--font-mono);
  font-size: 0.9rem;
  color: var(--ink-soft);
}

/* ---------- v0.6 FAQ ---------- */

.faq-list {
  max-width: 52rem;
  margin-top: 3rem;
  border-bottom: 1.5px solid var(--ink);
}

.faq-item {
  border-top: 1.5px solid var(--ink);
}

.faq-item summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
  min-height: 56px;
  padding: 0.9rem 0;
  cursor: pointer;
  list-style: none;
}

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

.faq-item summary h3 {
  margin: 0;
}

.faq-marker {
  position: relative;
  width: 1.1rem;
  height: 1.1rem;
  flex-shrink: 0;
}

.faq-marker::before,
.faq-marker::after {
  content: "";
  position: absolute;
  background: var(--accent);
}

.faq-marker::before {
  top: 50%;
  left: 0;
  right: 0;
  height: 2px;
  transform: translateY(-50%);
}

.faq-marker::after {
  left: 50%;
  top: 0;
  bottom: 0;
  width: 2px;
  transform: translateX(-50%);
  transition: transform 0.2s ease-out, opacity 0.2s ease-out;
}

.faq-item[open] .faq-marker::after {
  transform: translateX(-50%) scaleY(0);
  opacity: 0;
}

.faq-item::details-content {
  block-size: 0;
  overflow: clip;
  transition: block-size 0.2s ease, content-visibility 0.2s ease allow-discrete;
}

.faq-item[open]::details-content {
  block-size: auto;
}

.faq-answer {
  padding-bottom: 1.25rem;
}

.faq-answer p {
  max-width: var(--measure);
  color: var(--ink-soft);
}

.faq-answer a {
  color: var(--accent);
}

/* ---------- v0.5 Contact ---------- */

.section-contact {
  padding-bottom: clamp(4rem, 10vw, 8rem);
}

.contact-panel {
  padding: clamp(2.5rem, 6vw, 4.5rem);
  border-radius: 14px;
  background: var(--ink);
  color: var(--paper);
}

.contact-panel .eyebrow {
  color: #9FB4F0;
}

.contact-panel .section-lede {
  color: #C6D4D2;
}

.contact-panel .btn {
  margin-top: 2.25rem;
}

/* ---------- Footer ---------- */

.site-footer {
  padding: 1rem var(--gutter);
  border-top: 1px solid var(--ink);
  background: var(--paper);
  font-size: 0.9rem;
  color: var(--ink-soft);
}

.footer-note {
  margin-top: 0.35rem;
  font-family: var(--font-mono);
  font-size: 0.8rem;
}

.footer-note a {
  color: inherit;
}

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

.footer-share {
  margin-top: 1rem;
}

.share-icon {
  width: 1rem;
  height: 1rem;
  margin-right: 0.5rem;
  flex-shrink: 0;
}

.share-status {
  min-height: 1.6em;
  margin-top: 0.6rem;
  font-family: var(--font-mono);
  font-size: 0.8rem;
}

/* ---------- Desktop layout ---------- */

@media (min-width: 46rem) {
  .cycle-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .site-footer {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem 2rem;
  }

  .footer-text {
    display: flex;
    flex: 1;
    min-width: 0;
    flex-wrap: wrap;
    align-items: baseline;
    gap: 0.25rem 1.5rem;
  }

  .footer-text .footer-note {
    margin-top: 0;
  }

  .footer-share {
    display: flex;
    align-items: center;
    gap: 1rem;
    flex-shrink: 0;
    margin-top: 0;
  }

  .share-status {
    order: -1;
    min-height: 0;
    margin-top: 0;
    max-width: 40vw;
    text-align: right;
  }

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

  .engagement-steps {
    grid-template-columns: repeat(3, 1fr);
  }

  .privacy-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

@media (min-width: 62rem) {
  .hero {
    grid-template-columns: minmax(0, 1.15fr) minmax(0, 0.85fr);
    gap: 4rem;
  }

  .cycle-grid {
    grid-template-columns: repeat(4, 1fr);
  }

  .services-list {
    grid-template-columns: repeat(3, 1fr);
  }
}

/* ---------- Reduced motion ---------- */

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  .loop-dash {
    animation: none;
  }

  .btn,
  .skip-link,
  .faq-marker::after,
  .faq-item::details-content,
  .site-nav,
  .nav-toggle-bar {
    transition: none;
  }

  .btn:hover {
    transform: none;
  }
}