/* Curtis Bitcoin Corporation — design system
   Professional, calm, Bitcoin-aligned. Light/dark via data-theme. */

:root {
  --font-sans: "Segoe UI", system-ui, -apple-system, BlinkMacSystemFont, Roboto, "Helvetica Neue", sans-serif;
  --font-serif: "Iowan Old Style", "Palatino Linotype", Palatino, Georgia, "Times New Roman", serif;
  --measure: 70ch;
  --page: 1120px;
  --radius: 12px;
  --shadow: 0 1px 2px rgb(0 0 0 / 0.06), 0 8px 24px rgb(0 0 0 / 0.06);
  --header-h: 4.25rem;
  --ease: 180ms ease;
}

html[data-theme="light"],
:root {
  --bg: #f4f1ea;
  --bg-alt: #ebe6dc;
  --surface: #fffcf7;
  --text: #1c1917;
  --muted: #57534e;
  --faint: #78716c;
  --line: #ddd6cb;
  --primary: #0f5c44;
  --primary-hover: #0a4332;
  --primary-soft: #dcece4;
  --accent: #b45309;
  --accent-soft: #fde8c8;
  --warn: #92400e;
  --warn-bg: #fef3c7;
  --danger: #9f1239;
  --focus: #0f5c44;
  --header-bg: rgb(244 241 234 / 0.88);
  --invert: #0e1210;
  --on-primary: #fff;
  --mark: #f7931a;
}

html[data-theme="dark"] {
  --bg: #0e1210;
  --bg-alt: #141a17;
  --surface: #171e1b;
  --text: #f5f2eb;
  --muted: #c4bdb2;
  --faint: #9a9288;
  --line: #2c3531;
  --primary: #5ee0a8;
  --primary-hover: #86efc0;
  --primary-soft: #143328;
  --accent: #fbbf24;
  --accent-soft: #3a2a10;
  --warn: #fcd34d;
  --warn-bg: #2a220c;
  --danger: #fda4af;
  --focus: #5ee0a8;
  --header-bg: rgb(14 18 16 / 0.88);
  --invert: #f4f1ea;
  --on-primary: #0e1210;
  --mark: #f7931a;
  --shadow: 0 1px 2px rgb(0 0 0 / 0.4), 0 10px 28px rgb(0 0 0 / 0.28);
}

@media (prefers-color-scheme: dark) {
  html:not([data-theme]) {
    --bg: #0e1210;
    --bg-alt: #141a17;
    --surface: #171e1b;
    --text: #f5f2eb;
    --muted: #c4bdb2;
    --faint: #9a9288;
    --line: #2c3531;
    --primary: #5ee0a8;
    --primary-hover: #86efc0;
    --primary-soft: #143328;
    --accent: #fbbf24;
    --accent-soft: #3a2a10;
    --warn: #fcd34d;
    --warn-bg: #2a220c;
    --danger: #fda4af;
    --focus: #5ee0a8;
    --header-bg: rgb(14 18 16 / 0.88);
    --invert: #f4f1ea;
    --on-primary: #0e1210;
    --mark: #f7931a;
    --shadow: 0 1px 2px rgb(0 0 0 / 0.4), 0 10px 28px rgb(0 0 0 / 0.28);
  }
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation: none !important;
    transition: none !important;
  }
}

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: 1.05rem;
  line-height: 1.65;
  color: var(--text);
  background: var(--bg);
  min-height: 100vh;
}

img { max-width: 100%; height: auto; }
a { color: var(--primary); text-underline-offset: 0.18em; }
a:hover { color: var(--primary-hover); }

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

.skip-link {
  position: absolute;
  left: 1rem;
  top: -4rem;
  background: var(--primary);
  color: var(--on-primary);
  padding: 0.5rem 0.9rem;
  z-index: 2000;
  border-radius: 6px;
}
.skip-link:focus { top: 0.75rem; }

.wrap {
  width: min(var(--page), calc(100% - 2.5rem));
  margin-inline: auto;
}

.prose { max-width: var(--measure); }
.prose h2, .prose h3 { scroll-margin-top: 5.5rem; }
.prose p + p { margin-top: 1rem; }
.prose ul, .prose ol { padding-left: 1.25rem; }
.prose li + li { margin-top: 0.35rem; }

/* Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: var(--header-bg);
  backdrop-filter: saturate(1.4) blur(12px);
  border-bottom: 1px solid var(--line);
}

.header-inner {
  width: min(var(--page), calc(100% - 2.5rem));
  margin-inline: auto;
  min-height: var(--header-h);
  display: flex;
  align-items: center;
  gap: 1.25rem;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  text-decoration: none;
  color: var(--text);
  flex-shrink: 0;
}
.brand:hover { color: var(--text); }

.brand-mark {
  width: 2.15rem;
  height: 2.15rem;
  border-radius: 50%;
  background: var(--mark);
  color: #fff;
  display: grid;
  place-items: center;
  font-weight: 700;
  font-size: 1.15rem;
  line-height: 1;
}

.brand-text {
  display: flex;
  flex-direction: column;
  line-height: 1.1;
}
.brand-name {
  font-family: var(--font-serif);
  font-weight: 700;
  font-size: 1.02rem;
  letter-spacing: -0.02em;
  white-space: nowrap;
}
.brand-sub {
  font-size: 0.72rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--faint);
}

.site-nav {
  margin-left: auto;
}
.site-nav ul {
  display: flex;
  gap: 0.15rem 1.35rem;
  list-style: none;
  margin: 0;
  padding: 0;
}
.site-nav a {
  color: var(--muted);
  text-decoration: none;
  font-size: 0.95rem;
  font-weight: 500;
  padding: 0.35rem 0;
  border-bottom: 2px solid transparent;
}
.site-nav a:hover,
.site-nav a[aria-current="page"] {
  color: var(--text);
  border-bottom-color: var(--mark);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  flex-shrink: 0;
}

.theme-toggle,
.nav-toggle {
  background: transparent;
  border: 1px solid var(--line);
  color: var(--text);
  border-radius: 999px;
  padding: 0.35rem 0.75rem;
  font: inherit;
  font-size: 0.85rem;
  cursor: pointer;
}
.theme-toggle:hover,
.nav-toggle:hover {
  background: var(--surface);
}

.nav-toggle { display: none; }

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
  padding: 0.8rem 1.25rem;
  border-radius: 999px;
  text-decoration: none;
  font-weight: 650;
  font-size: 0.95rem;
  border: 1px solid transparent;
  background: var(--primary);
  color: var(--on-primary);
  cursor: pointer;
  transition: transform var(--ease), box-shadow var(--ease), background var(--ease);
}
.btn:hover {
  background: var(--primary-hover);
  color: var(--on-primary);
  transform: translateY(-1px);
}
.btn-sm { padding: 0.45rem 0.9rem; font-size: 0.85rem; }
.btn-ghost {
  background: transparent;
  color: var(--text);
  border-color: var(--line);
}
.btn-ghost:hover {
  background: var(--surface);
  color: var(--text);
}
.btn-row { display: flex; flex-wrap: wrap; gap: 0.75rem; }

/* Hero */
.hero {
  padding: 4.5rem 0 3.5rem;
  border-bottom: 1px solid var(--line);
  background:
    radial-gradient(1200px 400px at 80% -10%, rgb(247 147 26 / 0.12), transparent 60%),
    var(--bg);
}
.eyebrow {
  display: inline-block;
  font-size: 0.78rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--accent);
  font-weight: 650;
  margin-bottom: 0.85rem;
}
.hero h1 {
  font-family: var(--font-serif);
  font-size: clamp(2.4rem, 6vw, 4.1rem);
  line-height: 1.08;
  letter-spacing: -0.03em;
  font-weight: 700;
  margin: 0 0 1rem;
  max-width: 16ch;
}
.hero .lede {
  font-size: 1.2rem;
  color: var(--muted);
  max-width: 42ch;
  margin: 0 0 1.75rem;
}

.ticker {
  display: flex;
  flex-wrap: wrap;
  gap: 1.25rem 2rem;
  align-items: baseline;
  padding: 0.9rem 0;
  border-bottom: 1px solid var(--line);
  font-size: 0.92rem;
  color: var(--muted);
}
.ticker strong { color: var(--text); font-variant-numeric: tabular-nums; }
.ticker-label { letter-spacing: 0.08em; text-transform: uppercase; font-size: 0.72rem; }

/* Sections */
.section { padding: 4rem 0; }
.section + .section { border-top: 1px solid var(--line); }
.section-alt { background: var(--bg-alt); }
.section h2,
.page-hero h1 {
  font-family: var(--font-serif);
  font-size: clamp(1.8rem, 3vw, 2.4rem);
  letter-spacing: -0.025em;
  margin: 0 0 0.6rem;
  line-height: 1.15;
}
.section-intro {
  color: var(--muted);
  max-width: 52ch;
  margin: 0 0 2rem;
}

.page-hero {
  padding: 3.25rem 0 2rem;
  border-bottom: 1px solid var(--line);
}
.page-hero p {
  color: var(--muted);
  max-width: 54ch;
  margin: 0;
}

.grid-3,
.grid-2,
.grid-4 {
  display: grid;
  gap: 1.15rem;
}
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }

.card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 1.35rem 1.4rem 1.45rem;
  box-shadow: var(--shadow);
}
.card h3 {
  font-family: var(--font-serif);
  font-size: 1.2rem;
  margin: 0 0 0.45rem;
}
.card p { margin: 0; color: var(--muted); }
.card .icon {
  display: block;
  font-size: 1.25rem;
  margin-bottom: 0.55rem;
}

.steps {
  display: grid;
  gap: 1rem;
  counter-reset: step;
}
.step {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 1rem;
  align-items: start;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 1.1rem 1.2rem;
}
.step::before {
  counter-increment: step;
  content: counter(step);
  width: 2rem;
  height: 2rem;
  border-radius: 50%;
  background: var(--primary);
  color: var(--on-primary);
  display: grid;
  place-items: center;
  font-weight: 700;
  font-size: 0.9rem;
  margin-top: 0.15rem;
}
.step h3 { margin: 0 0 0.25rem; font-size: 1.05rem; }
.step p { margin: 0; color: var(--muted); }

.callout,
.note,
.warning {
  border-radius: var(--radius);
  padding: 1rem 1.15rem;
  margin: 1.25rem 0;
}
.callout {
  background: var(--primary-soft);
  border-left: 4px solid var(--primary);
}
.warning {
  background: var(--warn-bg);
  border-left: 4px solid var(--accent);
  color: var(--text);
}
.note {
  background: var(--surface);
  border: 1px solid var(--line);
}

.toc {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 1.1rem 1.25rem;
  margin: 0 0 2rem;
}
.toc h2 { font-size: 0.95rem; margin: 0 0 0.5rem; font-family: var(--font-sans); letter-spacing: 0.04em; text-transform: uppercase; color: var(--faint); }
.toc ol { margin: 0; padding-left: 1.2rem; columns: 2; gap: 2rem; }
.toc a { text-decoration: none; }

.table-wrap { overflow-x: auto; margin: 1.25rem 0; }
table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.95rem;
  background: var(--surface);
}
caption {
  text-align: left;
  font-weight: 650;
  margin-bottom: 0.5rem;
  color: var(--muted);
}
th, td {
  border: 1px solid var(--line);
  padding: 0.65rem 0.8rem;
  text-align: left;
  vertical-align: top;
}
th { background: var(--bg-alt); font-weight: 650; }

.split {
  display: grid;
  grid-template-columns: 1.15fr 0.85fr;
  gap: 1.5rem;
  align-items: start;
}

.qr-box {
  text-align: center;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 1.25rem;
}
.qr-box img {
  width: 180px;
  height: 180px;
  object-fit: contain;
  background: #fff;
  padding: 0.4rem;
  border-radius: 8px;
}
.qr-box p { color: var(--muted); font-size: 0.9rem; margin: 0.6rem 0 0; }

.resource {
  display: grid;
  gap: 0.35rem;
}
.resource h3 { margin: 0; font-size: 1.1rem; }
.resource .meta { font-size: 0.85rem; color: var(--faint); }
.resource p { margin: 0; }

.cta-band {
  background: var(--invert);
  color: var(--bg);
  padding: 3.25rem 0;
}
html[data-theme="dark"] .cta-band {
  background: #f4f1ea;
  color: #0e1210;
}
.cta-band h2 { color: inherit; }
.cta-band p { color: inherit; opacity: 0.8; max-width: 48ch; }
.cta-band .btn { background: var(--mark); color: #fff; }
.cta-band .btn:hover { background: #e07b00; color: #fff; }
.cta-band .btn-ghost {
  color: inherit;
  border-color: currentColor;
  background: transparent;
}
.cta-band .btn-ghost:hover {
  background: rgb(255 255 255 / 0.1);
  color: inherit;
}

/* Footer */
.site-footer {
  border-top: 1px solid var(--line);
  padding: 2.5rem 0 2rem;
  background: var(--bg-alt);
  font-size: 0.95rem;
}
.footer-grid {
  display: grid;
  grid-template-columns: 1.4fr 1fr 1fr;
  gap: 1.5rem 2rem;
}
.footer-name {
  font-family: var(--font-serif);
  font-size: 1.2rem;
  margin: 0 0 0.35rem;
}
.footer-tag, .site-footer p { color: var(--muted); }
.site-footer nav ul { list-style: none; margin: 0; padding: 0; }
.site-footer nav a { color: var(--muted); text-decoration: none; }
.site-footer nav a:hover { color: var(--text); }
.site-footer h3 {
  font-size: 0.75rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  margin: 0 0 0.55rem;
  color: var(--faint);
}
.disclaimer {
  margin-top: 2rem;
  padding-top: 1.25rem;
  border-top: 1px solid var(--line);
  font-size: 0.85rem;
  color: var(--faint);
  max-width: 80ch;
}
.copyright {
  margin: 0.75rem 0 0;
  font-size: 0.85rem;
  color: var(--faint);
}

.contact-block a { font-weight: 650; }

/* Mobile */
@media (max-width: 860px) {
  .nav-toggle { display: inline-flex; margin-left: auto; }
  .site-nav {
    display: none;
    position: absolute;
    left: 0;
    right: 0;
    top: 100%;
    background: var(--surface);
    border-bottom: 1px solid var(--line);
    margin: 0;
    padding: 0.75rem 1.25rem 1rem;
  }
  body.nav-open .site-nav { display: block; }
  .site-nav ul { flex-direction: column; gap: 0.35rem; }
  .header-actions .btn-sm { display: none; }
  .grid-2, .grid-3, .grid-4, .split, .footer-grid, .toc ol {
    grid-template-columns: 1fr;
    columns: 1;
  }
  .hero { padding-top: 2.75rem; }
}

@media print {
  .site-header, .theme-toggle, .nav-toggle, .cta-band, .btn, .ticker { display: none !important; }
  body { background: #fff; color: #111; }
  a { color: #111; }
}