/* ============================================================
   GBooks Air — marketing + help centre
   Design system: "The Ledger" — double-entry vernacular,
   ruled totals, account-code eyebrows, mono figures.
   ============================================================ */

:root{
  --ink:      #0E2227;
  --ink-2:    #1A3A44;
  --ink-soft: #40606B;
  --paper:    #F7FAFA;
  --card:     #FFFFFF;
  --teal:     #3CA8BB;
  --teal-deep:#1E6C7C;
  --teal-wash:#E7F3F5;
  --debit:    #B9502F;
  --line:     #D9E4E6;
  --line-soft:#E8EFF0;
  --shadow:   0 1px 2px rgba(14,34,39,.05), 0 8px 28px rgba(14,34,39,.07);
  --shadow-lg:0 2px 4px rgba(14,34,39,.06), 0 20px 50px rgba(14,34,39,.12);
  --radius:   14px;
  --font-display:"Fraunces", Georgia, serif;
  --font-body:"Manrope", -apple-system, "Segoe UI", sans-serif;
  --font-mono:"IBM Plex Mono", "SF Mono", Menlo, monospace;
  --maxw: 1140px;
  --maxw-prose: 720px;
}

*,*::before,*::after{ box-sizing:border-box; }
html{ scroll-behavior:smooth; -webkit-text-size-adjust:100%; }
@media (prefers-reduced-motion: reduce){
  html{ scroll-behavior:auto; }
  *,*::before,*::after{ animation:none !important; transition:none !important; }
}
body{
  margin:0;
  font-family:var(--font-body);
  font-size:16.5px;
  line-height:1.65;
  color:var(--ink);
  background:var(--paper);
  -webkit-font-smoothing:antialiased;
}

::selection{ background:var(--teal); color:#fff; }

/* custom scrollbar — webkit */
::-webkit-scrollbar{ width:11px; height:11px; }
::-webkit-scrollbar-track{ background:var(--paper); }
::-webkit-scrollbar-thumb{ background:#C3D6D9; border-radius:999px; border:3px solid var(--paper); }
::-webkit-scrollbar-thumb:hover{ background:#9FBCC1; }
html{ scrollbar-color:#C3D6D9 var(--paper); scrollbar-width:thin; }

.mono, .ledger-card, .doc-meta, .eyebrow, .feature-visual, .card .kicker{ font-variant-numeric:tabular-nums; }

/* subtle paper-grain texture for depth on dark / hero surfaces */
.grain{ position:relative; isolation:isolate; }
.grain::before{
  content:""; position:absolute; inset:0; z-index:0; pointer-events:none; opacity:.5; mix-blend-mode:overlay;
  background-image:url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='120' height='120'><filter id='n'><feTurbulence type='fractalNoise' baseFrequency='0.85' numOctaves='2' stitchTiles='stitch'/><feColorMatrix type='matrix' values='0 0 0 0 1  0 0 0 0 1  0 0 0 0 1  0 0 0 0.035 0'/></filter><rect width='100%25' height='100%25' filter='url(%23n)'/></svg>");
}
.grain > *{ position:relative; z-index:1; }

/* scroll reveal */
.reveal{ opacity:0; transform:translateY(16px); transition:opacity .7s ease, transform .7s cubic-bezier(.16,.8,.3,1); }
.reveal.in{ opacity:1; transform:translateY(0); }
@media (prefers-reduced-motion: reduce){ .reveal{ opacity:1; transform:none; transition:none; } }

img,svg{ max-width:100%; height:auto; }
a{ color:var(--teal-deep); text-decoration:none; }
a:hover{ text-decoration:underline; text-underline-offset:3px; }
:focus-visible{ outline:2.5px solid var(--teal); outline-offset:2px; border-radius:4px; }

.wrap{ max-width:var(--maxw); margin:0 auto; padding:0 24px; }

/* ---------- Type ---------- */
h1,h2,h3,h4{ font-family:var(--font-display); font-weight:560; line-height:1.14; margin:0 0 .5em; letter-spacing:-.01em; color:var(--ink); }
h1{ font-size:clamp(2.3rem, 5.2vw, 3.6rem); }
h2{ font-size:clamp(1.7rem, 3.4vw, 2.35rem); }
h3{ font-size:1.32rem; line-height:1.3; }
h4{ font-size:1.08rem; font-family:var(--font-body); font-weight:700; }
p{ margin:0 0 1em; }
.lede{ font-size:1.16rem; color:var(--ink-soft); max-width:640px; }

.eyebrow{
  font-family:var(--font-mono);
  font-size:.74rem;
  letter-spacing:.14em;
  text-transform:uppercase;
  color:var(--teal-deep);
  display:flex; align-items:center; gap:.6em;
  margin-bottom:1.1em;
}
.eyebrow::before{ content:""; width:26px; height:1px; background:var(--teal); flex:none; }

/* Ledger total rule — the signature heading device */
.ruled{
  padding-bottom:.45em;
  border-bottom:1px solid var(--ink);
  box-shadow:0 4px 0 -1px var(--paper), 0 5px 0 -1px var(--ink);
  display:inline-block;
}

/* ---------- Header ---------- */
.site-header{
  position:sticky; top:0; z-index:60;
  background:rgba(247,250,250,.88);
  backdrop-filter:saturate(160%) blur(10px);
  border-bottom:1px solid var(--line-soft);
}
.site-header .wrap{
  display:flex; align-items:center; gap:28px;
  min-height:72px; padding-top:10px; padding-bottom:10px;
}
.brand{ display:flex; align-items:center; gap:9px; font-family:var(--font-display); font-size:1.22rem; font-weight:600; color:var(--ink); line-height:1; }
.brand:hover{ text-decoration:none; }
.brand-mark{ width:30px; height:30px; flex:none; display:block; }
.brand-name{ display:inline-flex; align-items:baseline; gap:.28em; white-space:nowrap; }
.brand-air{ color:var(--teal-deep); font-style:italic; font-weight:500; }
.site-footer .brand-air{ color:var(--teal); }
.brand small{ font-family:var(--font-mono); font-size:.6rem; letter-spacing:.12em; color:var(--teal-deep); align-self:flex-end; margin-bottom:2px; }
.site-nav{ display:flex; gap:26px; margin-left:auto; align-items:center; }
.site-nav a{ color:var(--ink-2); font-weight:600; font-size:.94rem; }
.site-nav a.active{ color:var(--teal-deep); }
.site-nav a:hover{ text-decoration:none; color:var(--teal-deep); }

.btn{
  display:inline-flex; align-items:center; justify-content:center; gap:.5em;
  font-family:var(--font-body); font-weight:700; font-size:.95rem; line-height:1.2;
  padding:.85em 1.4em; border-radius:999px; border:1.5px solid transparent;
  cursor:pointer; transition:transform .15s ease, box-shadow .2s ease, background .15s ease;
  white-space:nowrap; flex:none; height:auto; min-height:0;
}
.btn span{ display:inline-block; line-height:1.2; }
.btn:hover{ text-decoration:none; transform:translateY(-1px); }
.btn:active{ transform:translateY(0); }
.btn-primary{ background:var(--ink); color:#fff; box-shadow:var(--shadow); }
.btn-primary:hover{ background:var(--ink-2); box-shadow:var(--shadow-lg); }
.btn-teal{ background:var(--teal-deep); color:#fff; box-shadow:0 1px 2px rgba(14,34,39,.08), 0 6px 18px rgba(60,168,187,.28); }
.btn-teal:hover{ background:#185b69; box-shadow:0 2px 4px rgba(14,34,39,.1), 0 10px 26px rgba(60,168,187,.4); }
.btn-ghost{ background:transparent; color:var(--ink); border-color:var(--line); }
.btn-ghost:hover{ border-color:var(--ink-soft); background:rgba(14,34,39,.03); }
.btn-lg{ font-size:1.04rem; padding:.95em 1.8em; }

/* mobile nav */
.nav-toggle{ display:none; margin-left:auto; background:none; border:1px solid var(--line); border-radius:8px; padding:8px 10px; cursor:pointer; }
.nav-toggle span{ display:block; width:18px; height:2px; background:var(--ink); margin:3.5px 0; border-radius:2px; }
@media (max-width: 860px){
  .site-nav{
    display:none;
    position:absolute; top:66px; left:0; right:0;
    background:var(--card); border-bottom:1px solid var(--line);
    flex-direction:column; align-items:flex-start; gap:0; padding:10px 24px 18px;
    box-shadow:var(--shadow-lg);
  }
  .site-nav.open{ display:flex; }
  .site-nav a{ padding:11px 0; width:100%; border-bottom:1px solid var(--line-soft); }
  .site-nav .btn{ margin-top:12px; width:100%; }
  .nav-toggle{ display:block; }
}

/* ---------- Hero ---------- */
.hero{ padding:78px 0 64px; position:relative; overflow:hidden; }
.hero::before{
  content:""; position:absolute; inset:0; pointer-events:none;
  background:
    repeating-linear-gradient(to bottom, transparent 0 35px, rgba(30,108,124,.045) 35px 36px);
  mask-image:linear-gradient(to bottom, #000 0%, transparent 85%);
}
.hero .wrap{ display:grid; grid-template-columns:1.05fr .95fr; gap:56px; align-items:center; position:relative; }
@media (max-width: 940px){ .hero .wrap{ grid-template-columns:1fr; } }
.hero h1 .accent{ color:var(--teal-deep); font-style:italic; font-weight:500; }
.hero-ctas{ display:flex; gap:14px; margin:26px 0 18px; flex-wrap:wrap; }
.hero-note{ font-family:var(--font-mono); font-size:.78rem; color:var(--ink-soft); display:flex; gap:1.4em; flex-wrap:wrap; }
.hero-note span::before{ content:"✓"; color:var(--teal-deep); margin-right:.45em; font-weight:700; }

/* Ledger card in hero */
.ledger-card{
  background:var(--card); border:1px solid var(--line); border-radius:var(--radius);
  box-shadow:var(--shadow-lg); padding:26px 26px 20px; font-family:var(--font-mono);
  font-size:.82rem; color:var(--ink-2);
  transition:transform .15s ease-out; will-change:transform;
}
.ledger-card .lc-head{
  display:flex; justify-content:space-between; align-items:baseline;
  font-size:.7rem; letter-spacing:.12em; text-transform:uppercase; color:var(--ink-soft);
  padding-bottom:10px; border-bottom:1px solid var(--line);
  margin-bottom:6px;
}
.ledger-card table{ width:100%; border-collapse:collapse; }
.ledger-card td{ padding:8px 0; border-bottom:1px dashed var(--line-soft); }
.ledger-card td:nth-child(2), .ledger-card td:nth-child(3){ text-align:right; width:86px; }
.ledger-card .dr{ color:var(--debit); }
.ledger-card .cr{ color:var(--teal-deep); }
.ledger-card tr.total td{
  border-bottom:none; border-top:1px solid var(--ink); font-weight:600; color:var(--ink);
  position:relative;
}
.ledger-card tr.total td::after{
  content:""; position:absolute; left:0; right:0; bottom:-4px; border-bottom:1px solid var(--ink);
}
.ledger-card .lc-foot{ margin-top:16px; font-size:.68rem; color:var(--ink-soft); display:flex; justify-content:space-between; }
.badge-balanced{ color:var(--teal-deep); font-weight:600; }

/* ---------- Sections ---------- */
.section{ padding:72px 0; }
.section-tight{ padding:56px 0; }
.section-ink{ background:var(--ink); color:#E8F1F2; }
.section-ink h2, .section-ink h3{ color:#fff; }
.section-ink .lede{ color:#A9C4CA; }
.section-ink .eyebrow{ color:var(--teal); }
.section-wash{ background:var(--teal-wash); }
.section-head{ margin-bottom:40px; max-width:680px; }

.grid-3{ display:grid; grid-template-columns:repeat(3,1fr); gap:22px; }
.grid-2{ display:grid; grid-template-columns:repeat(2,1fr); gap:22px; }
.grid-4{ display:grid; grid-template-columns:repeat(4,1fr); gap:22px; }
@media (max-width: 940px){ .grid-3,.grid-4{ grid-template-columns:repeat(2,1fr); } }
@media (max-width: 640px){ .grid-3,.grid-2,.grid-4{ grid-template-columns:1fr; } }

.card{
  background:var(--card); border:1px solid var(--line); border-radius:var(--radius);
  padding:26px; box-shadow:var(--shadow);
  transition:transform .18s ease, box-shadow .18s ease, border-color .18s ease;
}
a.card{ color:inherit; display:block; }
a.card:hover{ text-decoration:none; transform:translateY(-3px); box-shadow:var(--shadow-lg); border-color:#B7DCE2; }

/* receipt-edge divider: the scalloped tear you'd get pulling a paper ledger off its pad */
.receipt-edge{ position:relative; height:22px; background:var(--paper); }
.receipt-edge::before{
  content:""; position:absolute; top:0; left:0; right:0; height:22px;
  background-image:radial-gradient(circle at 11px 0, transparent 11px, var(--ink) 11.5px);
  background-size:22px 22px; background-repeat:repeat-x; background-position:top center;
}
.receipt-edge.to-paper::before{ background-image:radial-gradient(circle at 11px 0, transparent 11px, var(--ink) 11.5px); }
.card .kicker{
  font-family:var(--font-mono); font-size:.68rem; letter-spacing:.13em; text-transform:uppercase;
  color:var(--teal-deep); margin-bottom:10px;
}
.card h3{ margin-bottom:.35em; }
.card p{ color:var(--ink-soft); font-size:.95rem; margin-bottom:0; }
.card .card-count{ font-family:var(--font-mono); font-size:.72rem; color:var(--ink-soft); margin-top:14px; display:block; }

.section-ink .card{ background:var(--ink-2); border-color:#28505C; box-shadow:none; }
.section-ink .card h3{ color:#fff; }
.section-ink .card p{ color:#A9C4CA; }

/* feature list rows */
.feature-row{ display:grid; grid-template-columns:.9fr 1.1fr; gap:52px; align-items:center; padding:44px 0; border-top:1px solid var(--line-soft); }
.feature-row:first-of-type{ border-top:none; }
.feature-row.flip{ direction:rtl; }
.feature-row.flip > *{ direction:ltr; }
@media (max-width: 860px){ .feature-row, .feature-row.flip{ grid-template-columns:1fr; direction:ltr; gap:24px; padding:32px 0; } }
.feature-row h3{ font-size:1.55rem; }
.feature-row p{ color:var(--ink-soft); }
.feature-visual{
  background:var(--card); border:1px solid var(--line); border-radius:var(--radius);
  box-shadow:var(--shadow); padding:22px; font-family:var(--font-mono); font-size:.8rem; color:var(--ink-2);
}

/* checklist */
.checks{ list-style:none; padding:0; margin:14px 0 0; }
.checks li{ padding-left:1.7em; position:relative; margin-bottom:.55em; color:var(--ink-2); }
.checks li::before{ content:"✓"; position:absolute; left:0; color:var(--teal-deep); font-weight:800; }

/* ---------- Footer ---------- */
.site-footer{ background:var(--ink); color:#9FBCC3; padding:56px 0 32px; margin-top:0; font-size:.92rem; }
.site-footer a{ color:#CFE2E6; }
.site-footer h4{ color:#fff; font-size:.8rem; font-family:var(--font-mono); letter-spacing:.13em; text-transform:uppercase; margin-bottom:14px; font-weight:600; }
.footer-grid{ display:grid; grid-template-columns:1.4fr 1fr 1fr 1fr; gap:36px; margin-bottom:40px; }
@media (max-width: 860px){ .footer-grid{ grid-template-columns:1fr 1fr; } }
@media (max-width: 560px){ .footer-grid{ grid-template-columns:1fr; } }
.site-footer ul{ list-style:none; padding:0; margin:0; }
.site-footer li{ margin-bottom:.55em; }
.footer-bottom{ border-top:1px solid #24444E; padding-top:22px; display:flex; justify-content:space-between; gap:16px; flex-wrap:wrap; font-size:.82rem; font-family:var(--font-mono); }

/* ---------- Help centre ---------- */
.help-hero{ padding:64px 0 44px; text-align:center; }
.help-hero h1{ font-size:clamp(2rem,4.4vw,3rem); }
.help-search{ max-width:620px; margin:26px auto 0; position:relative; }
.help-search input{
  width:100%; padding:15px 20px 15px 50px; font-size:1rem; font-family:var(--font-body);
  border:1.5px solid var(--line); border-radius:999px; background:var(--card);
  box-shadow:var(--shadow); color:var(--ink);
}
.help-search input:focus{ outline:none; border-color:var(--teal); box-shadow:0 0 0 4px rgba(60,168,187,.15); }
.help-search .hs-icon{ position:absolute; left:19px; top:50%; transform:translateY(-50%); color:var(--ink-soft); }
.help-search-results{
  position:absolute; top:calc(100% + 8px); left:0; right:0; z-index:40;
  background:var(--card); border:1px solid var(--line); border-radius:14px; box-shadow:var(--shadow-lg);
  max-height:380px; overflow:auto; text-align:left; display:none;
}
.help-search-results.open{ display:block; }
.help-search-results a{ display:block; padding:13px 18px; border-bottom:1px solid var(--line-soft); color:var(--ink); }
.help-search-results a:last-child{ border-bottom:none; }
.help-search-results a:hover{ background:var(--teal-wash); text-decoration:none; }
.help-search-results .r-title{ font-weight:700; font-size:.95rem; }
.help-search-results .r-sec{ font-family:var(--font-mono); font-size:.68rem; color:var(--teal-deep); text-transform:uppercase; letter-spacing:.1em; }
.help-search-results .r-empty{ padding:16px 18px; color:var(--ink-soft); font-size:.92rem; }

/* Docs layout */
.docs-layout{ display:grid; grid-template-columns:270px minmax(0,1fr); gap:56px; padding:44px 0 80px; }
@media (max-width: 940px){ .docs-layout{ grid-template-columns:1fr; gap:20px; } }
.docs-sidebar{ position:sticky; top:92px; align-self:start; font-size:.92rem; max-height:calc(100vh - 120px); overflow:auto; padding-right:6px; }
@media (max-width: 940px){ .docs-sidebar{ position:static; max-height:none; border:1px solid var(--line); border-radius:var(--radius); padding:18px; background:var(--card); } }
.docs-sidebar .sb-group{ margin-bottom:26px; }
.docs-sidebar .sb-title{
  font-family:var(--font-mono); font-size:.68rem; letter-spacing:.13em; text-transform:uppercase;
  color:var(--ink-soft); margin-bottom:10px; display:flex; gap:.6em; align-items:baseline;
}
.docs-sidebar .sb-title .code{ color:var(--teal-deep); }
.docs-sidebar ul{ list-style:none; margin:0; padding:0 0 0 2px; border-left:1px solid var(--line); }
.docs-sidebar li a{
  display:block; padding:6px 0 6px 14px; color:var(--ink-2); border-left:2px solid transparent; margin-left:-2px;
}
.docs-sidebar li a:hover{ color:var(--teal-deep); text-decoration:none; }
.docs-sidebar li a.active{ color:var(--teal-deep); font-weight:700; border-left-color:var(--teal-deep); }

.docs-main{ max-width:var(--maxw-prose); }
.breadcrumbs{ font-family:var(--font-mono); font-size:.74rem; color:var(--ink-soft); margin-bottom:22px; }
.breadcrumbs a{ color:var(--ink-soft); }
.breadcrumbs a:hover{ color:var(--teal-deep); }
.breadcrumbs .sep{ margin:0 .5em; color:var(--line); }
.doc-meta{ font-family:var(--font-mono); font-size:.74rem; color:var(--ink-soft); margin:-6px 0 26px; display:flex; gap:1.6em; }

.docs-main h1{ font-size:clamp(1.9rem,3.6vw,2.5rem); margin-bottom:.35em; }
.docs-main h2{ font-size:1.5rem; margin-top:2em; padding-bottom:.35em; border-bottom:1px solid var(--line-soft); }
.docs-main h3{ font-size:1.15rem; margin-top:1.6em; }
.docs-main p, .docs-main li{ color:var(--ink-2); }
.docs-main ol, .docs-main ul{ padding-left:1.35em; margin:0 0 1.1em; }
.docs-main li{ margin-bottom:.45em; }
.docs-main li::marker{ color:var(--teal-deep); font-weight:700; }
.docs-main strong{ color:var(--ink); }
.docs-main code{
  font-family:var(--font-mono); font-size:.85em; background:var(--teal-wash);
  padding:.15em .45em; border-radius:6px; color:var(--teal-deep);
}
.docs-main table{ width:100%; border-collapse:collapse; margin:0 0 1.3em; font-size:.92rem; }
.docs-main th{ text-align:left; font-family:var(--font-mono); font-size:.7rem; text-transform:uppercase; letter-spacing:.1em; color:var(--ink-soft); border-bottom:1.5px solid var(--ink); padding:8px 12px 8px 0; }
.docs-main td{ border-bottom:1px solid var(--line-soft); padding:9px 12px 9px 0; vertical-align:top; }

.callout{
  border:1px solid var(--line); border-left:4px solid var(--teal); border-radius:10px;
  background:var(--card); padding:16px 20px; margin:1.4em 0; font-size:.95rem;
}
.callout.warn{ border-left-color:var(--debit); }
.callout .co-label{ font-family:var(--font-mono); font-size:.68rem; letter-spacing:.12em; text-transform:uppercase; color:var(--teal-deep); display:block; margin-bottom:.35em; font-weight:600; }
.callout.warn .co-label{ color:var(--debit); }
.callout p:last-child{ margin-bottom:0; }

.doc-pager{ display:flex; justify-content:space-between; gap:16px; margin-top:56px; padding-top:26px; border-top:1px solid var(--line); }
.doc-pager a{ max-width:47%; }
.doc-pager .pg-label{ font-family:var(--font-mono); font-size:.68rem; letter-spacing:.12em; text-transform:uppercase; color:var(--ink-soft); display:block; margin-bottom:4px; }
.doc-pager .pg-title{ font-weight:700; color:var(--ink); }
.doc-pager a:hover{ text-decoration:none; }
.doc-pager a:hover .pg-title{ color:var(--teal-deep); }
.doc-pager .next{ text-align:right; margin-left:auto; }

.doc-help-cta{
  margin-top:56px; background:var(--teal-wash); border:1px solid var(--line);
  border-radius:var(--radius); padding:24px 28px; display:flex; justify-content:space-between; align-items:center; gap:20px; flex-wrap:wrap;
}
.doc-help-cta p{ margin:0; color:var(--ink-2); }
.doc-help-cta strong{ display:block; font-size:1.05rem; }

/* article index cards on hub */
.hub-grid{ display:grid; grid-template-columns:repeat(2,1fr); gap:22px; }
@media (max-width: 720px){ .hub-grid{ grid-template-columns:1fr; } }
.hub-card .hub-links{ list-style:none; margin:16px 0 0; padding:0; font-size:.93rem; }
.hub-card .hub-links li{ padding:7px 0; border-top:1px dashed var(--line-soft); }
.hub-card .hub-links a{ color:var(--ink-2); font-weight:600; }
.hub-card .hub-links a:hover{ color:var(--teal-deep); text-decoration:none; }
.hub-card .hub-more{ font-family:var(--font-mono); font-size:.74rem; }

/* FAQ */
.faq-item{ border-bottom:1px solid var(--line-soft); }
.faq-item summary{
  cursor:pointer; list-style:none; padding:20px 34px 20px 0; font-weight:700; font-size:1.05rem; position:relative;
}
.faq-item summary::-webkit-details-marker{ display:none; }
.faq-item summary::after{ content:"+"; position:absolute; right:6px; top:50%; transform:translateY(-50%); font-family:var(--font-mono); font-size:1.2rem; color:var(--teal-deep); }
.faq-item[open] summary::after{ content:"–"; }
.faq-item .faq-body{ padding:0 0 22px; color:var(--ink-soft); max-width:640px; }
.faq-body p:last-child{ margin-bottom:0; }

/* big CTA band */
.cta-band{ text-align:center; padding:84px 24px; }
.cta-band h2{ font-size:clamp(1.9rem,4vw,2.8rem); margin-bottom:.4em; }
.cta-band p{ max-width:520px; margin:0 auto 1.8em; color:var(--ink-soft); }
.section-ink .cta-band p, .cta-band.section-ink p{ color:#A9C4CA; }

/* util */
.mt-0{margin-top:0}.mb-0{margin-bottom:0}
.center{text-align:center}
.muted{color:var(--ink-soft)}
.mono{font-family:var(--font-mono)}