/* Hydronexa Solutions — sticky chapter rail + chapter pages */
:root {
  --navy:        #284868;
  --navy-mid:    #305070;
  --navy-deep:   #1A3348;
  --navy-ink:    #132838;
  --cyan:        #50A8C8;
  --cyan-bright: #58B0C8;
  --cyan-soft:   #90C8D8;
  --paper:       #F3F8FA;
  --sheet:       #FFFFFF;
  --mist:        #D8E8F0;
  --text:        #1A3348;
  --muted:       #3D5668;
  --line:        #C5D8E4;
  --text-inv:    #F4FAFC;
  --muted-inv:   #D0E4EE;
  --line-inv:    rgba(244, 250, 252, 0.22);
  --rail:        212px;
  --header-h:    68px;
  --ease:        cubic-bezier(.22, .61, .36, 1);
  --serif:       "Literata", "Palatino Linotype", Palatino, serif;
  --sans:        "Commissioner", system-ui, -apple-system, sans-serif;
  --radius:      12px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }

body {
  margin: 0;
  background: var(--paper);
  color: var(--text);
  font-family: var(--sans);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

h1, h2, h3, .brand-name, .pull, .rail-no, .study-no, .control-no {
  font-family: var(--serif);
  letter-spacing: -0.03em;
  line-height: 1.12;
  margin: 0;
}

a { color: inherit; text-decoration: none; }
img { max-width: 100%; display: block; }
p { margin: 0; }
ul { margin: 0; padding: 0; list-style: none; }

.skip-link {
  position: absolute; left: -999px; top: 0; z-index: 400;
  background: var(--navy); color: var(--text-inv);
  padding: 10px 16px; font-weight: 600;
}
.skip-link:focus { left: 0; }

.kicker {
  margin: 0 0 12px;
  font-size: 12px;
  letter-spacing: .2em;
  text-transform: uppercase;
  font-weight: 600;
  color: var(--cyan);
}

.btn {
  display: inline-flex; align-items: center; justify-content: center;
  padding: 13px 24px; border-radius: 999px; font-weight: 600; font-size: 14.5px;
  border: 1px solid transparent; cursor: pointer;
  transition: background .25s var(--ease), box-shadow .25s var(--ease), border-color .25s var(--ease), color .25s var(--ease);
}
.btn-primary {
  background: var(--navy); color: var(--text-inv);
  box-shadow: 0 8px 22px -10px rgba(40, 72, 104, .55);
}
.btn-ghost {
  background: transparent; color: var(--text); border-color: var(--navy);
}

/* ===== Header ===== */
.site-header {
  position: fixed; inset: 0 0 auto 0; z-index: 120;
  height: var(--header-h);
  background: rgba(243, 248, 250, .86);
  backdrop-filter: saturate(160%) blur(14px);
  border-bottom: 1px solid transparent;
  transition: background .3s var(--ease), border-color .3s var(--ease);
}
.site-header.scrolled {
  background: rgba(243, 248, 250, .97);
  border-bottom-color: var(--line);
}
.header-inner {
  display: flex; align-items: center; gap: 16px;
  height: var(--header-h);
  padding: 0 22px 0 20px;
}
.brand { display: inline-flex; align-items: center; gap: 11px; min-width: 0; }
.brand img {
  width: 40px; height: 40px; border-radius: 10px;
  background: #fff; box-shadow: 0 0 0 1px var(--line);
}
.brand-lockup { display: flex; flex-direction: column; line-height: 1.05; }
.brand-name { font-size: 18px; font-weight: 650; }
.brand-sub {
  font-family: var(--sans); font-size: 11px; font-weight: 600;
  letter-spacing: .16em; text-transform: uppercase; color: var(--cyan);
}
.header-place {
  margin-left: auto;
  font-size: 12px; letter-spacing: .16em; text-transform: uppercase;
  font-weight: 600; color: var(--muted); white-space: nowrap;
}
.header-mail {
  font-size: 13px; font-weight: 650; color: var(--navy);
  border-bottom: 1px solid var(--cyan);
  padding-bottom: 2px;
}
.nav-toggle {
  display: none;
  width: 42px; height: 42px; border: 0; background: transparent;
  padding: 0; cursor: pointer; flex-direction: column;
  align-items: center; justify-content: center; gap: 5px;
}
.nav-toggle span {
  display: block; width: 20px; height: 2px; background: var(--navy); border-radius: 2px;
}

/* ===== Frame: rail + pages ===== */
.frame {
  display: flex;
  align-items: flex-start;
  padding-top: var(--header-h);
}

.chapter-rail {
  position: sticky; top: var(--header-h);
  flex: 0 0 var(--rail);
  width: var(--rail);
  height: calc(100svh - var(--header-h));
  display: flex; flex-direction: column; gap: 4px;
  padding: 28px 16px 28px 18px;
  background: var(--navy-ink);
  color: var(--text-inv);
  z-index: 80;
  overflow: auto;
}
.rail-kicker {
  font-size: 11px; letter-spacing: .22em; text-transform: uppercase;
  font-weight: 650; color: var(--cyan-soft); margin: 0 0 14px;
}
.chapter-rail a {
  display: grid; grid-template-columns: 36px 1fr; gap: 10px; align-items: baseline;
  padding: 10px 10px; border-radius: 8px;
  color: var(--muted-inv); font-weight: 500;
  border: 1px solid transparent;
  transition: background .25s var(--ease), color .25s var(--ease), border-color .25s var(--ease);
}
.rail-no {
  font-size: 13px; font-weight: 650; color: var(--cyan);
  letter-spacing: 0;
}
.rail-label { font-size: 15px; }
.chapter-rail a.is-active {
  background: rgba(80, 168, 200, .16);
  border-color: rgba(80, 168, 200, .4);
  color: var(--text-inv);
}
.chapter-rail a.is-active .rail-no { color: var(--cyan-bright); }
.rail-ink {
  margin-top: auto;
  width: 8px; height: 72px; border-radius: 99px;
  background: linear-gradient(180deg, var(--cyan-bright), var(--navy));
  align-self: flex-start;
  animation: ink-rise 4.5s var(--ease) infinite alternate;
}
@keyframes ink-rise {
  from { height: 48px; opacity: .7; }
  to { height: 92px; opacity: 1; }
}

/* ===== Chapter pages ===== */
main { flex: 1; min-width: 0; }

.chapter.page {
  position: relative;
  min-height: calc(100svh - var(--header-h));
  scroll-margin-top: calc(var(--header-h) + 8px);
  background: var(--sheet);
  margin: 18px 18px 18px 0;
  padding: 28px 40px 22px;
  border: 1px solid var(--line);
  box-shadow: 0 18px 40px -28px rgba(26, 51, 72, .35);
  display: flex; flex-direction: column;
}
.chapter.page + .chapter.page { margin-top: 0; }
.chapter.page:last-of-type { margin-bottom: 18px; }
.chapter.page.page-mist { background: var(--paper); }
.chapter.page.page-dark {
  background: var(--navy-deep);
  color: var(--text-inv);
  border-color: transparent;
}
.page-dark .page-running,
.page-dark .page-foot { color: var(--muted-inv); border-color: var(--line-inv); }
.page-dark h2 { color: var(--text-inv); }
.page-dark .lead,
.page-dark .control-card p { color: var(--muted-inv); }
.page-dark .kicker { color: var(--cyan-bright); }

.page-rule {
  position: absolute; left: 22px; top: 18px; bottom: 18px;
  width: 2px;
  background: repeating-linear-gradient(
    to bottom,
    var(--cyan) 0 10px,
    transparent 10px 18px
  );
  opacity: .45;
}
.page-dark .page-rule { opacity: .35; }

.page-running {
  display: flex; justify-content: space-between; gap: 12px;
  padding: 0 0 16px 28px;
  border-bottom: 1px solid var(--line);
  font-size: 12px; letter-spacing: .16em; text-transform: uppercase;
  font-weight: 650; color: var(--muted);
}
.page-foot {
  display: flex; justify-content: space-between; gap: 12px;
  margin-top: auto; padding: 16px 0 0 28px;
  border-top: 1px solid var(--line);
  font-size: 12px; letter-spacing: .14em; text-transform: uppercase;
  font-weight: 600; color: var(--muted);
}
.page-body {
  padding: 36px 8px 36px 28px;
  flex: 1;
}
.page-body h2 {
  font-size: clamp(1.7rem, 3.4vw, 2.55rem);
  font-weight: 600;
  max-width: 18ch;
  margin-bottom: 22px;
}

/* ===== Opening / hero ===== */
.page-open { background: var(--sheet); }
.hero-body {
  display: grid;
  grid-template-columns: 1.05fr .95fr;
  gap: 32px;
  align-items: center;
}
.eyebrow {
  font-size: 12px; letter-spacing: .2em; text-transform: uppercase;
  font-weight: 650; color: var(--cyan); margin-bottom: 14px;
}
.hero-copy h1 {
  font-size: clamp(2.4rem, 5.4vw, 4.1rem);
  font-weight: 650;
  color: var(--navy-deep);
  margin-bottom: 18px;
}
.hero-sub {
  font-size: 1.08rem; color: var(--muted); max-width: 42ch; margin-bottom: 26px;
}
.hero-actions { display: flex; flex-wrap: wrap; gap: 12px; }

.hero-stage { position: relative; justify-self: center; width: min(100%, 380px); }
.flow-svg { width: 100%; height: auto; overflow: visible; }
.grid-dots { fill: var(--cyan-soft); opacity: .7; }
.pipe-net { opacity: .9; }
.pipe {
  stroke-dasharray: 8 14;
  animation: pipe-flow 7s linear infinite;
}
.pipe.p2 { animation-duration: 9s; animation-direction: reverse; }
@keyframes pipe-flow { to { stroke-dashoffset: -220; } }

.swirl { transform-origin: 180px 180px; animation: swirl-turn 18s linear infinite; }
@keyframes swirl-turn { to { transform: rotate(360deg); } }
.swirl-tip.t1 { animation: tip-flick 2.8s ease-in-out infinite; }
.swirl-tip.t2 { animation: tip-flick 2.8s ease-in-out infinite reverse; }
@keyframes tip-flick {
  0%, 100% { transform: rotate(0deg); }
  50% { transform: rotate(8deg); }
}

.drop { fill: var(--cyan); }
.d1 { offset-path: path("M30 180 H120 C150 180 150 120 180 120 H330"); animation: ride 6.5s linear infinite; }
.d2 { offset-path: path("M30 240 H100 C140 240 140 300 180 300 H330"); animation: ride 8s linear infinite 1.2s; fill: var(--navy); }
.d3 { offset-path: path("M180 40 V330"); animation: ride 7.2s linear infinite .6s; }
@keyframes ride {
  0% { offset-distance: 0%; opacity: 0; }
  8% { opacity: 1; }
  92% { opacity: 1; }
  100% { offset-distance: 100%; opacity: 0; }
}
.nodes circle {
  fill: var(--sheet); stroke: var(--navy); stroke-width: 2.5;
  transform-box: fill-box; transform-origin: center;
  animation: node-pulse 3.2s ease-in-out infinite;
}
.nodes circle:nth-child(odd) { animation-delay: .8s; }
@keyframes node-pulse {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.18); }
}
.stage-caption {
  text-align: center; margin-top: 8px;
  font-size: 11px; letter-spacing: .18em; text-transform: uppercase;
  font-weight: 650; color: var(--muted);
}

/* ===== Practice ===== */
.split {
  display: grid; grid-template-columns: .9fr 1.1fr; gap: 36px;
  margin-bottom: 36px;
}
.split-lead p {
  font-family: var(--serif); font-size: 1.28rem; line-height: 1.45; font-weight: 500;
}
.split-copy { display: grid; gap: 14px; color: var(--muted); }

.study-row {
  display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px;
}
.study-card {
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 22px 20px;
  transition: border-color .3s var(--ease), box-shadow .3s var(--ease), background .3s var(--ease);
}
.study-no {
  display: block; font-size: 1.5rem; color: var(--cyan); margin-bottom: 8px;
}
.study-card h3 { font-size: 1.2rem; margin-bottom: 8px; }
.study-card p { color: var(--muted); font-size: .98rem; }

/* ===== Networks ===== */
.lead { color: var(--muted); max-width: 58ch; margin: -8px 0 28px; }
.demand-stack { display: grid; gap: 14px; }
.demand-card {
  background: var(--sheet);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 24px 26px;
  display: grid;
  grid-template-columns: 140px 1fr;
  gap: 8px 28px;
  align-items: start;
  transition: border-color .3s var(--ease), box-shadow .3s var(--ease), transform .3s var(--ease);
}
.demand-tag {
  grid-row: span 2;
  font-size: 12px; letter-spacing: .18em; text-transform: uppercase;
  font-weight: 700; color: var(--navy);
  padding-top: 6px;
}
.demand-card h3 { font-size: 1.35rem; font-weight: 600; }
.demand-card p { color: var(--muted); }

/* ===== Control ===== */
.control-grid {
  display: grid; grid-template-columns: 1fr 1fr; gap: 14px;
}
.control-card {
  background: rgba(80, 168, 200, .12);
  border: 1px solid var(--line-inv);
  border-radius: var(--radius);
  padding: 24px 22px;
  transition: border-color .3s var(--ease), background .3s var(--ease), transform .3s var(--ease);
}
.control-no {
  display: block; font-size: 1.35rem; color: var(--cyan-bright); margin-bottom: 8px;
}
.control-card h3 { font-size: 1.25rem; color: var(--text-inv); margin-bottom: 8px; }

/* ===== Steward ===== */
.pull {
  margin: 8px 0 12px;
  font-size: clamp(1.5rem, 3.2vw, 2.25rem);
  font-weight: 600;
  line-height: 1.28;
  max-width: 22ch;
  color: var(--navy);
}
.pull-attr {
  font-size: 12px; letter-spacing: .16em; text-transform: uppercase;
  font-weight: 650; color: var(--muted); margin-bottom: 28px;
}
.steward-copy {
  display: grid; gap: 14px; color: var(--muted); max-width: 62ch;
}

/* ===== FAQ ===== */
.faq-list { display: grid; gap: 12px; max-width: 760px; }
.faq-item {
  background: var(--sheet);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  transition: border-color .3s var(--ease);
}
.faq-item.open { border-color: var(--cyan); }
.faq-q {
  width: 100%; display: flex; align-items: center; justify-content: space-between; gap: 16px;
  background: none; border: 0; cursor: pointer; text-align: left; color: var(--text);
  font-family: var(--sans); font-size: 1.05rem; font-weight: 600;
  padding: 20px 22px;
}
.faq-ico { position: relative; flex: 0 0 auto; width: 16px; height: 16px; }
.faq-ico::before, .faq-ico::after {
  content: ""; position: absolute; background: var(--navy); border-radius: 2px;
  transition: transform .3s var(--ease), opacity .3s var(--ease);
}
.faq-ico::before { top: 7px; left: 0; width: 16px; height: 2px; }
.faq-ico::after { top: 0; left: 7px; width: 2px; height: 16px; }
.faq-item.open .faq-ico::after { transform: scaleY(0); opacity: 0; }
.faq-a { max-height: 0; overflow: hidden; transition: max-height .35s ease; }
.faq-item.open .faq-a { max-height: 280px; }
.faq-a p { color: var(--muted); margin: 0; padding: 0 22px 20px; font-size: .98rem; }

/* ===== Contact ===== */
.contact-body {
  display: grid; grid-template-columns: 1fr 1fr; gap: 48px; align-items: start;
}
.contact-copy h2 { max-width: 14ch; }
.contact-copy p { color: var(--muted-inv); margin-bottom: 18px; }
.contact-email {
  display: inline-block;
  font-family: var(--serif);
  font-size: clamp(1.2rem, 2.2vw, 1.65rem);
  font-weight: 600;
  color: var(--text-inv);
  border-bottom: 1px solid transparent;
}
.contact-addr { margin-top: 18px; color: var(--muted-inv); }
.contact-form {
  background: rgba(80, 168, 200, .12);
  border: 1px solid var(--line-inv);
  border-radius: var(--radius);
  padding: 26px;
  display: grid; gap: 14px;
  transition: border-color .3s var(--ease);
}
.field { display: grid; gap: 6px; }
.field label { font-size: 13px; color: var(--muted-inv); font-weight: 600; }
.field input, .field textarea {
  background: var(--navy-ink);
  border: 1px solid var(--line-inv);
  border-radius: 10px;
  color: var(--text-inv);
  padding: 12px 14px;
  font: inherit; font-size: 15px;
  width: 100%; resize: vertical;
}
.field input::placeholder, .field textarea::placeholder { color: rgba(208, 228, 238, .55); }
.field input:focus, .field textarea:focus { outline: none; border-color: var(--cyan-bright); }
.page-dark .btn-primary {
  background: var(--cyan); color: var(--navy-ink);
  box-shadow: 0 8px 22px -10px rgba(80, 168, 200, .55);
}

/* ===== Footer ===== */
.site-footer {
  margin-left: var(--rail);
  background: var(--sheet);
  border-top: 1px solid var(--line);
  padding: 36px 28px 22px;
}
.footer-inner {
  display: flex; align-items: center; justify-content: space-between; gap: 20px;
  margin-bottom: 22px;
}
.footer-nav { display: flex; flex-wrap: wrap; gap: 18px; font-weight: 600; color: var(--muted); }
.footer-bottom {
  display: flex; justify-content: space-between; gap: 12px; flex-wrap: wrap;
  border-top: 1px solid var(--line); padding-top: 16px;
  color: var(--muted); font-size: 14px;
}

/* ===== Reveal ===== */
.js .reveal {
  opacity: 0;
  transform: translateY(22px);
  transition: opacity .7s var(--ease), transform .7s var(--ease);
}
.js .reveal.in { opacity: 1; transform: none; }
@media (prefers-reduced-motion: reduce) {
  .js .reveal { opacity: 1; transform: none; transition: none; }
  .swirl, .pipe, .drop, .nodes circle, .rail-ink, .swirl-tip { animation: none; }
}

/* Hover AFTER reveal.in so lift is not overwritten */
@media (hover: hover) and (pointer: fine) {
  .btn { transition: transform .25s var(--ease), background .25s var(--ease), box-shadow .25s var(--ease), border-color .25s var(--ease), color .25s var(--ease); }
  .btn-primary:hover {
    transform: translateY(-2px);
    background: var(--navy-mid);
    box-shadow: 0 14px 32px -10px rgba(40, 72, 104, .65);
  }
  .page-dark .btn-primary:hover {
    background: var(--cyan-bright);
    color: var(--navy-ink);
  }
  .btn-ghost:hover {
    transform: translateY(-2px);
    border-color: var(--cyan);
    color: var(--navy);
  }
  .header-mail:hover { color: var(--cyan); }
  .chapter-rail a:hover {
    background: rgba(80, 168, 200, .12);
    color: var(--text-inv);
  }
  .study-card.reveal.in:hover,
  .study-card:hover {
    transform: translateY(-5px);
    border-color: var(--cyan);
    box-shadow: 0 16px 32px -18px rgba(40, 72, 104, .28);
  }
  .demand-card.reveal.in:hover,
  .demand-card:hover {
    transform: translateY(-4px);
    border-color: var(--cyan);
    box-shadow: 0 16px 32px -18px rgba(40, 72, 104, .28);
  }
  .control-card.reveal.in:hover,
  .control-card:hover {
    transform: translateY(-5px);
    border-color: var(--cyan-bright);
    background: rgba(80, 168, 200, .22);
  }
  .faq-item:hover { border-color: var(--cyan); }
  .faq-q:hover { color: var(--navy-deep); }
  .contact-email:hover { border-bottom-color: var(--text-inv); }
  .footer-nav a:hover { color: var(--navy); }
  .contact-form.reveal.in:hover,
  .contact-form:hover { border-color: var(--cyan-bright); }
}

@media (hover: none) {
  .btn-primary { background: var(--navy); color: var(--text-inv); }
  .page-dark .btn-primary { background: var(--cyan); color: var(--navy-ink); }
  .btn-ghost { color: var(--text); border-color: var(--navy); }
  .faq-q { color: var(--text); }
  .control-card p, .contact-copy p, .contact-addr { color: var(--muted-inv); }
}

/* ===== Desktop page height ===== */
@media (min-width: 981px) {
  .page-open { min-height: calc(100svh - var(--header-h) - 18px); }
}

/* ===== Tablet ===== */
@media (max-width: 1040px) {
  .hero-body,
  .split,
  .contact-body,
  .control-grid { grid-template-columns: 1fr; }
  .demand-card { grid-template-columns: 1fr; gap: 6px; }
  .demand-tag { grid-row: auto; }
  .study-row { grid-template-columns: 1fr 1fr; }
}

/* ===== Mobile: rail stacks ===== */
@media (max-width: 860px) {
  .nav-toggle { display: none; }
  .header-place { display: none; }
  .header-mail { display: inline-block; margin-left: auto; font-size: 12px; }
  .header-inner { padding: 0 16px; }

  .frame { display: block; padding-top: var(--header-h); }

  .chapter-rail {
    position: static;
    width: 100%;
    height: auto;
    flex: none;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 8px;
    padding: 14px 16px 16px;
    background: var(--navy-ink);
  }
  .chapter-rail.open {
    display: grid;
  }
  .rail-kicker { grid-column: 1 / -1; margin-bottom: 4px; }
  .rail-ink { display: none; }
  .chapter-rail a {
    padding: 8px 10px;
    background: rgba(80, 168, 200, .1);
    border-color: var(--line-inv);
    gap: 6px;
    grid-template-columns: 28px 1fr;
  }
  .rail-label { font-size: 13px; }
  .chapter-rail a:last-of-type { grid-column: 1 / -1; }

  .chapter.page {
    margin: 12px 12px 0;
    padding: 20px 18px 16px;
    min-height: 0;
  }
  .page-rule { left: 12px; top: 14px; bottom: 14px; }
  .page-running, .page-foot, .page-body { padding-left: 18px; }
  .page-body { padding-top: 24px; padding-bottom: 24px; padding-right: 4px; }
  .site-footer { margin-left: 0; padding: 28px 18px 18px; }
}

@media (max-width: 720px) {
  .hero-copy h1 { font-size: clamp(2.1rem, 11vw, 3rem); }
  .study-row,
  .control-grid { grid-template-columns: 1fr; }
  .hero-actions { gap: 10px; }
  .footer-inner { flex-direction: column; align-items: flex-start; }
}

@media (max-width: 480px) {
  .header-inner { padding: 0 14px; }
  .brand-name { font-size: 16px; }
  .chapter.page { margin: 10px 10px 0; padding: 16px 14px 14px; }
  .page-body { padding: 20px 2px 20px 16px; }
  .page-running, .page-foot { padding-left: 16px; font-size: 11px; }
  .btn { width: 100%; }
  .hero-actions { width: 100%; }
  .hero-sub { font-size: 1.02rem; }
  .study-card, .demand-card, .control-card { padding: 18px 16px; }
  .contact-form { padding: 20px 16px; }
  .faq-q { padding: 16px 14px; font-size: 1rem; }
  .contact-body { gap: 28px; }
  .page-body h2 { margin-bottom: 16px; }
  .split { gap: 18px; margin-bottom: 24px; }
  .chapter-rail { padding: 12px 12px 14px; gap: 8px; }
  .site-footer { padding: 24px 16px 16px; }
}

@media (prefers-reduced-motion: reduce) {
  .nodes circle { animation: none; }
}