/* =========================================================================
   FUNCTIONAL PRESCIENCE™
   Stylesheet — formal release edition
   ========================================================================= */

/* -------------------------------------------------------------------------
   01 · Design tokens
   ------------------------------------------------------------------------- */
:root {
  /* Surface */
  --bg:              #0a0a0b;
  --bg-raised:       #111113;
  --bg-inset:        #070708;
  --rule:            #24232a;
  --rule-strong:     #3a3842;

  /* Ink */
  --ink:             #e8e5df;
  --ink-muted:       #8b8780;
  --ink-faint:       #5a5752;
  --ink-inverse:     #0a0a0b;

  /* Accent — a single restrained warm metallic */
  --accent:          #c4a574;
  --accent-deep:     #8e7547;

  /* Critical / state */
  --signal:          #d6cba8;
  --error:           #c97b6a;

  /* Type */
  --font-display:    "Spectral", "Iowan Old Style", "Palatino Linotype", Palatino, "Georgia", serif;
  --font-body:       "Spectral", "Iowan Old Style", "Palatino Linotype", Palatino, "Georgia", serif;
  --font-mono:       "JetBrains Mono", "IBM Plex Mono", "SF Mono", Menlo, Consolas, monospace;

  /* Scale */
  --fs-mono:         0.7rem;
  --fs-small:        0.875rem;
  --fs-body:         1.0625rem;
  --fs-lede:         1.375rem;
  --fs-h3:           1.625rem;
  --fs-h2:           2.5rem;
  --fs-h1:           clamp(3rem, 8vw, 6.25rem);
  --fs-hero:         clamp(3.5rem, 10vw, 8.5rem);

  /* Rhythm */
  --lh-tight:        1.05;
  --lh-snug:         1.2;
  --lh-body:         1.55;
  --tk-tight:        -0.02em;
  --tk-wide:         0.16em;

  /* Space */
  --s-1:             0.25rem;
  --s-2:             0.5rem;
  --s-3:             1rem;
  --s-4:             1.5rem;
  --s-5:             2.5rem;
  --s-6:             4rem;
  --s-7:             6.5rem;
  --s-8:             10.5rem;

  /* Layout */
  --measure:         34rem;
  --measure-wide:    62rem;
  --gutter:          clamp(1.25rem, 4vw, 3rem);
}

/* -------------------------------------------------------------------------
   02 · Reset + base
   ------------------------------------------------------------------------- */
*, *::before, *::after { box-sizing: border-box; }

html {
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 16px;
  font-feature-settings: "kern", "liga", "calt", "onum";
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-size: var(--fs-body);
  line-height: var(--lh-body);
  background:
    radial-gradient(ellipse 80% 60% at 50% 0%, rgba(196,165,116,0.04), transparent 70%),
    var(--bg);
  min-height: 100vh;
  overflow-x: hidden;
}

::selection {
  background: var(--accent);
  color: var(--ink-inverse);
}

img, svg { max-width: 100%; display: block; }
hr {
  border: 0;
  border-top: 1px solid var(--rule);
  margin: var(--s-6) 0;
}

/* -------------------------------------------------------------------------
   03 · Typography
   ------------------------------------------------------------------------- */
h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: 300;
  letter-spacing: var(--tk-tight);
  line-height: var(--lh-tight);
  color: var(--ink);
  margin: 0 0 var(--s-4);
}

.display {
  font-size: var(--fs-hero);
  line-height: 0.95;
  font-weight: 300;
  letter-spacing: -0.035em;
}

h1 { font-size: var(--fs-h1); font-weight: 300; }
h2 { font-size: var(--fs-h2); font-weight: 400; letter-spacing: -0.015em; }
h3 { font-size: var(--fs-h3); font-weight: 400; letter-spacing: -0.01em; line-height: var(--lh-snug); }
h4 { font-size: 1.125rem; font-weight: 500; letter-spacing: 0; }

p {
  margin: 0 0 var(--s-3);
  max-width: var(--measure);
}

.lede {
  font-size: var(--fs-lede);
  line-height: 1.45;
  color: var(--ink);
  font-weight: 300;
  max-width: 38rem;
}

.eyebrow,
.label {
  font-family: var(--font-mono);
  font-size: var(--fs-mono);
  text-transform: uppercase;
  letter-spacing: var(--tk-wide);
  color: var(--ink-muted);
  font-weight: 500;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: var(--s-2);
  margin-bottom: var(--s-4);
}

.eyebrow::before {
  content: "§";
  color: var(--accent);
  font-family: var(--font-display);
  font-size: 1rem;
  letter-spacing: 0;
  text-transform: none;
}

.section-no {
  font-family: var(--font-mono);
  font-size: var(--fs-mono);
  color: var(--accent);
  letter-spacing: var(--tk-wide);
  text-transform: uppercase;
}

.tm {
  font-size: 0.45em;
  vertical-align: super;
  letter-spacing: 0;
  font-weight: 400;
  margin-left: 0.05em;
  color: var(--accent);
}

.italic { font-style: italic; }

a {
  color: var(--ink);
  text-decoration: none;
  border-bottom: 1px solid var(--rule-strong);
  transition: border-color 200ms ease, color 200ms ease;
}
a:hover { border-color: var(--accent); color: var(--accent); }

.link-mono {
  font-family: var(--font-mono);
  font-size: var(--fs-mono);
  text-transform: uppercase;
  letter-spacing: var(--tk-wide);
  border: 0;
  color: var(--ink-muted);
}
.link-mono:hover { color: var(--accent); }
.link-mono::after {
  content: " →";
  display: inline-block;
  transition: transform 200ms ease;
}
.link-mono:hover::after { transform: translateX(3px); }

ul.bare, ol.bare {
  list-style: none;
  padding: 0;
  margin: 0;
}

ul.dot-list {
  list-style: none;
  padding: 0;
  margin: 0 0 var(--s-4);
}
ul.dot-list li {
  padding-left: var(--s-4);
  position: relative;
  margin-bottom: var(--s-2);
  max-width: var(--measure);
}
ul.dot-list li::before {
  content: "—";
  position: absolute;
  left: 0;
  color: var(--accent);
}

/* -------------------------------------------------------------------------
   04 · Layout primitives
   ------------------------------------------------------------------------- */
.container {
  width: 100%;
  max-width: 80rem;
  margin: 0 auto;
  padding: 0 var(--gutter);
}

.container-narrow {
  width: 100%;
  max-width: 48rem;
  margin: 0 auto;
  padding: 0 var(--gutter);
}

section {
  padding: var(--s-7) 0;
  border-top: 1px solid var(--rule);
}

section:first-of-type { border-top: 0; }

.section-head {
  display: grid;
  grid-template-columns: 6rem 1fr;
  gap: var(--s-5);
  margin-bottom: var(--s-6);
  align-items: baseline;
}

.section-head .section-no { padding-top: 0.4rem; }

@media (max-width: 720px) {
  .section-head { grid-template-columns: 1fr; gap: var(--s-2); }
}

.grid-2 {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--s-6);
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--s-5);
}

@media (max-width: 860px) {
  .grid-2, .grid-3 { grid-template-columns: 1fr; gap: var(--s-5); }
}

/* -------------------------------------------------------------------------
   05 · Header / nav
   ------------------------------------------------------------------------- */
.site-header {
  border-bottom: 1px solid var(--rule);
  background: rgba(10,10,11,0.85);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  position: sticky;
  top: 0;
  z-index: 50;
}

.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 4.5rem;
}

.brand {
  font-family: var(--font-display);
  font-size: 1.0625rem;
  font-weight: 400;
  letter-spacing: -0.005em;
  color: var(--ink);
  border: 0;
  display: inline-flex;
  align-items: baseline;
}
.brand:hover { color: var(--ink); }
.brand .tm { color: var(--accent); }

.nav {
  display: flex;
  align-items: center;
  gap: var(--s-5);
}

.nav a {
  font-family: var(--font-mono);
  font-size: var(--fs-mono);
  text-transform: uppercase;
  letter-spacing: var(--tk-wide);
  color: var(--ink-muted);
  border: 0;
  padding: var(--s-2) 0;
}
.nav a:hover,
.nav a[aria-current="page"] { color: var(--accent); }

.nav-toggle {
  display: none;
  background: none;
  border: 1px solid var(--rule-strong);
  color: var(--ink);
  padding: 0.4rem 0.7rem;
  font-family: var(--font-mono);
  font-size: var(--fs-mono);
  letter-spacing: var(--tk-wide);
  text-transform: uppercase;
  cursor: pointer;
}

@media (max-width: 820px) {
  .nav-toggle { display: inline-block; }
  .nav {
    display: none;
    position: absolute;
    top: 4.5rem;
    left: 0;
    right: 0;
    flex-direction: column;
    align-items: flex-start;
    gap: 0;
    background: var(--bg-raised);
    border-bottom: 1px solid var(--rule);
    padding: var(--s-3) var(--gutter);
  }
  .nav.open { display: flex; }
  .nav a { padding: var(--s-3) 0; border-bottom: 1px solid var(--rule); width: 100%; }
  .nav a:last-child { border-bottom: 0; }
}

/* -------------------------------------------------------------------------
   06 · Hero (home)
   ------------------------------------------------------------------------- */
.hero {
  padding: var(--s-8) 0 var(--s-7);
  border-top: 0;
  position: relative;
}

.hero-meta {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  margin-bottom: var(--s-6);
  padding-bottom: var(--s-3);
  border-bottom: 1px solid var(--rule);
  font-family: var(--font-mono);
  font-size: var(--fs-mono);
  text-transform: uppercase;
  letter-spacing: var(--tk-wide);
  color: var(--ink-muted);
}

.hero h1.display {
  margin: 0 0 var(--s-5);
  max-width: 14ch;
}

.hero-sub {
  font-family: var(--font-display);
  font-style: italic;
  font-weight: 300;
  font-size: clamp(1.25rem, 2.4vw, 1.75rem);
  color: var(--ink);
  max-width: 38rem;
  line-height: 1.35;
  margin: 0 0 var(--s-5);
}

.hero-positioning {
  max-width: 36rem;
  color: var(--ink-muted);
  font-size: 1.0625rem;
  line-height: 1.6;
}

.hero-cta {
  display: flex;
  gap: var(--s-3);
  margin-top: var(--s-6);
  flex-wrap: wrap;
}

/* -------------------------------------------------------------------------
   07 · Buttons
   ------------------------------------------------------------------------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--s-2);
  padding: 0.95rem 1.5rem;
  font-family: var(--font-mono);
  font-size: var(--fs-mono);
  text-transform: uppercase;
  letter-spacing: var(--tk-wide);
  border: 1px solid var(--rule-strong);
  background: transparent;
  color: var(--ink);
  cursor: pointer;
  transition: border-color 200ms ease, color 200ms ease, background 200ms ease;
  text-decoration: none;
}
.btn:hover {
  border-color: var(--accent);
  color: var(--accent);
}

.btn-primary {
  background: var(--accent);
  border-color: var(--accent);
  color: var(--ink-inverse);
}
.btn-primary:hover {
  background: var(--ink);
  border-color: var(--ink);
  color: var(--ink-inverse);
}

.btn-ghost {
  border-color: var(--rule);
  color: var(--ink-muted);
}
.btn-ghost:hover { color: var(--accent); border-color: var(--accent); }

.btn::after {
  content: "→";
  margin-left: 0.25rem;
  transition: transform 200ms ease;
}
.btn:hover::after { transform: translateX(3px); }

/* -------------------------------------------------------------------------
   08 · Tabular and structural blocks
   ------------------------------------------------------------------------- */
.spec-table {
  width: 100%;
  border-collapse: collapse;
  margin: var(--s-4) 0;
  font-size: 0.9375rem;
}
.spec-table th,
.spec-table td {
  text-align: left;
  padding: var(--s-3) var(--s-2);
  border-bottom: 1px solid var(--rule);
  vertical-align: top;
}
.spec-table th {
  font-family: var(--font-mono);
  font-size: var(--fs-mono);
  text-transform: uppercase;
  letter-spacing: var(--tk-wide);
  color: var(--ink-muted);
  font-weight: 500;
  width: 30%;
}

.bookcard {
  background: var(--bg-raised);
  border: 1px solid var(--rule);
  padding: var(--s-5);
  margin-bottom: var(--s-3);
  display: grid;
  grid-template-columns: 1fr auto;
  gap: var(--s-4);
  align-items: center;
}
.bookcard:hover { border-color: var(--rule-strong); }

.bookcard-format {
  font-family: var(--font-mono);
  font-size: var(--fs-mono);
  text-transform: uppercase;
  letter-spacing: var(--tk-wide);
  color: var(--ink-muted);
  margin-bottom: var(--s-1);
  display: block;
}
.bookcard-price {
  font-family: var(--font-display);
  font-size: 1.5rem;
  color: var(--ink);
  font-weight: 400;
}
.bookcard-desc {
  display: block;
  font-size: 0.9375rem;
  color: var(--ink-muted);
  margin-top: var(--s-2);
  font-style: italic;
}

@media (max-width: 600px) {
  .bookcard { grid-template-columns: 1fr; }
}

/* The "ledger" — for displaying access tiers like a catalog */
.ledger {
  border-top: 1px solid var(--rule);
}
.ledger-row {
  display: grid;
  grid-template-columns: 4rem 1fr;
  gap: var(--s-5);
  padding: var(--s-4) 0;
  border-bottom: 1px solid var(--rule);
  align-items: baseline;
}
.ledger-row .section-no { padding-top: 0; }
.ledger-row h4 {
  margin: 0 0 var(--s-2);
  font-family: var(--font-display);
  font-weight: 400;
  font-size: 1.25rem;
  letter-spacing: -0.005em;
}
.ledger-row p {
  margin: 0;
  color: var(--ink-muted);
  font-size: 0.9375rem;
}

@media (max-width: 600px) {
  .ledger-row { grid-template-columns: 1fr; gap: var(--s-2); }
}

/* -------------------------------------------------------------------------
   09 · Forms
   ------------------------------------------------------------------------- */
.form {
  display: grid;
  gap: var(--s-4);
  max-width: 36rem;
  margin-top: var(--s-5);
}

.form-row {
  display: grid;
  gap: var(--s-2);
}

.form-row.row-2 {
  grid-template-columns: 1fr 1fr;
  gap: var(--s-4);
}

@media (max-width: 600px) {
  .form-row.row-2 { grid-template-columns: 1fr; }
}

.form label {
  font-family: var(--font-mono);
  font-size: var(--fs-mono);
  text-transform: uppercase;
  letter-spacing: var(--tk-wide);
  color: var(--ink-muted);
}

.form input[type="text"],
.form input[type="email"],
.form input[type="url"],
.form select,
.form textarea {
  background: var(--bg-inset);
  border: 1px solid var(--rule);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 1rem;
  padding: 0.85rem 1rem;
  width: 100%;
  border-radius: 0;
  transition: border-color 200ms ease;
}

.form input:focus,
.form select:focus,
.form textarea:focus {
  outline: none;
  border-color: var(--accent);
}

.form textarea {
  min-height: 8rem;
  resize: vertical;
  line-height: 1.5;
  font-family: var(--font-body);
}

.form select {
  appearance: none;
  -webkit-appearance: none;
  background-image: linear-gradient(45deg, transparent 50%, var(--ink-muted) 50%),
                    linear-gradient(135deg, var(--ink-muted) 50%, transparent 50%);
  background-position: calc(100% - 1.25rem) 1.1rem, calc(100% - 1rem) 1.1rem;
  background-size: 6px 6px;
  background-repeat: no-repeat;
  padding-right: 2.5rem;
}

.checkbox-row {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: var(--s-3);
  align-items: start;
  padding: var(--s-3) 0;
  border-top: 1px solid var(--rule);
}

.checkbox-row input[type="checkbox"] {
  width: 1.1rem;
  height: 1.1rem;
  margin-top: 0.2rem;
  accent-color: var(--accent);
  cursor: pointer;
}

.checkbox-row label {
  text-transform: none;
  letter-spacing: 0;
  font-family: var(--font-body);
  font-size: 0.9375rem;
  color: var(--ink);
  line-height: 1.5;
  cursor: pointer;
}

.form-note {
  font-family: var(--font-mono);
  font-size: var(--fs-mono);
  color: var(--ink-faint);
  text-transform: uppercase;
  letter-spacing: var(--tk-wide);
}

.form-actions {
  margin-top: var(--s-3);
  display: flex;
  gap: var(--s-3);
  align-items: center;
}

.form-success,
.form-error {
  border: 1px solid var(--rule-strong);
  padding: var(--s-4);
  margin-top: var(--s-4);
  display: none;
}

.form-success {
  border-color: var(--accent-deep);
  color: var(--signal);
}
.form-success.is-visible,
.form-error.is-visible { display: block; }

.form-success .label,
.form-error .label { margin-bottom: var(--s-2); display: block; }

/* -------------------------------------------------------------------------
   10 · Footer
   ------------------------------------------------------------------------- */
.site-footer {
  border-top: 1px solid var(--rule);
  padding: var(--s-6) 0 var(--s-5);
  background: var(--bg-inset);
  margin-top: var(--s-7);
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: var(--s-5);
  margin-bottom: var(--s-5);
}

@media (max-width: 820px) {
  .footer-grid { grid-template-columns: 1fr 1fr; gap: var(--s-4); }
}
@media (max-width: 480px) {
  .footer-grid { grid-template-columns: 1fr; }
}

.footer-grid h5 {
  font-family: var(--font-mono);
  font-size: var(--fs-mono);
  text-transform: uppercase;
  letter-spacing: var(--tk-wide);
  color: var(--ink-muted);
  font-weight: 500;
  margin: 0 0 var(--s-3);
}

.footer-grid ul li { margin-bottom: var(--s-2); }
.footer-grid a {
  border: 0;
  color: var(--ink);
  font-size: 0.9375rem;
}
.footer-grid a:hover { color: var(--accent); }

.footer-mark {
  font-family: var(--font-display);
  font-size: 1.125rem;
  line-height: 1.3;
  margin-bottom: var(--s-2);
}
.footer-mark .tm { color: var(--accent); }

.footer-desc {
  color: var(--ink-muted);
  font-size: 0.875rem;
  line-height: 1.5;
  max-width: 22rem;
}

.footer-base {
  padding-top: var(--s-4);
  border-top: 1px solid var(--rule);
  display: flex;
  justify-content: space-between;
  font-family: var(--font-mono);
  font-size: var(--fs-mono);
  text-transform: uppercase;
  letter-spacing: var(--tk-wide);
  color: var(--ink-faint);
  flex-wrap: wrap;
  gap: var(--s-3);
}

/* -------------------------------------------------------------------------
   11 · Long-form (prose) pages
   ------------------------------------------------------------------------- */
.prose {
  max-width: var(--measure);
}
.prose p {
  font-size: 1.0625rem;
  line-height: 1.7;
  color: var(--ink);
  margin-bottom: var(--s-4);
}
.prose p:last-child { margin-bottom: 0; }
.prose h2 {
  margin-top: var(--s-6);
  margin-bottom: var(--s-3);
  font-size: 1.75rem;
}
.prose h3 {
  margin-top: var(--s-5);
  margin-bottom: var(--s-2);
  font-size: 1.25rem;
}
.prose strong { color: var(--ink); font-weight: 500; }
.prose em { color: var(--ink); font-style: italic; }
.prose ul {
  margin-bottom: var(--s-4);
  padding-left: var(--s-4);
}
.prose ul li {
  margin-bottom: var(--s-2);
  line-height: 1.6;
}

/* Page intro block used at top of inner pages */
.page-intro {
  padding: var(--s-7) 0 var(--s-5);
  border-bottom: 1px solid var(--rule);
}
.page-intro h1 {
  max-width: 16ch;
  margin: var(--s-2) 0 var(--s-4);
}
.page-intro .lede {
  color: var(--ink-muted);
}

/* -------------------------------------------------------------------------
   12 · Misc helpers
   ------------------------------------------------------------------------- */
.divider-mark {
  display: block;
  width: 2rem;
  height: 1px;
  background: var(--accent);
  margin: var(--s-4) 0;
}

.callout {
  border-left: 2px solid var(--accent);
  padding-left: var(--s-4);
  margin: var(--s-4) 0;
  color: var(--ink-muted);
  font-style: italic;
  max-width: var(--measure);
}

.muted { color: var(--ink-muted); }
.faint { color: var(--ink-faint); }

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  white-space: nowrap;
  border: 0;
}

/* Print: keep formal release readable on paper */
@media print {
  :root { --bg: #fff; --ink: #000; --ink-muted: #444; --rule: #ccc; }
  body { background: #fff; color: #000; }
  .site-header, .site-footer, .nav, .hero-cta { display: none; }
}