/* ─── RESET ─────────────────────────────────────────────── */
*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}
body {
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.6;
  overflow-x: hidden;
  transition: background var(--dur-med) var(--ease-mech), color var(--dur-med) var(--ease-mech);
}
img, svg { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
ul { list-style: none; }
button { font: inherit; color: inherit; background: none; border: none; cursor: pointer; }
::selection { background: var(--copper); color: #fff; }

/* faint drafting-paper grid, extremely subtle */
body {
  background-image:
    linear-gradient(var(--line) 1px, transparent 1px),
    linear-gradient(90deg, var(--line) 1px, transparent 1px);
  background-size: 64px 64px;
  background-position: center top;
  background-attachment: fixed;
}

/* ─── FOCUS ─────────────────────────────────────────────── */
:focus-visible {
  outline: 2px solid var(--copper);
  outline-offset: 3px;
  border-radius: var(--radius-sm);
}
a:focus:not(:focus-visible),
button:focus:not(:focus-visible) { outline: none; }

/* ─── SKIP LINK ─────────────────────────────────────────── */
.skip-link {
  position: fixed; top: -100px; left: 16px; z-index: 10000;
  background: var(--copper); color: #fff;
  padding: 12px 20px; border-radius: var(--radius-sm);
  font-family: var(--font-mono); font-size: 13px; font-weight: 600;
  transition: top var(--dur-fast) var(--ease-mech);
}
.skip-link:focus { top: 16px; }

/* ─── TYPOGRAPHY ────────────────────────────────────────── */
h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: 600;
  line-height: 1.1;
  letter-spacing: -0.01em;
}
.eyebrow {
  display: inline-flex; align-items: center; gap: var(--sp-2);
  font-family: var(--font-mono); font-size: 12px; font-weight: 500;
  color: var(--blue); letter-spacing: 0.12em; text-transform: uppercase;
  margin-bottom: var(--sp-4);
}
.eyebrow::before {
  content: ''; width: 8px; height: 1px; background: var(--blue);
}
.eyebrow .tag-num {
  color: var(--ink-faint);
}
h2.section-title {
  font-size: clamp(28px, 4vw, 44px);
  margin-bottom: var(--sp-3);
}
.section-sub {
  color: var(--ink-soft);
  max-width: 560px;
  font-size: 15.5px;
  line-height: 1.75;
}
.mono { font-family: var(--font-mono); }

/* ─── LAYOUT PRIMITIVES ─────────────────────────────────── */
.container {
  max-width: 1180px;
  margin: 0 auto;
  padding: 0 clamp(20px, 5vw, 56px);
}
main > section {
  position: relative;
  padding: var(--sp-9) 0;
  border-top: 1px solid var(--line);
}
main > section:first-of-type { border-top: none; }

.section-head {
  display: flex; flex-wrap: wrap; align-items: flex-end;
  justify-content: space-between; gap: var(--sp-5);
  margin-bottom: var(--sp-8);
}

/* panel: base surface for cards/components across the site */
.panel {
  background: var(--bg-panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

/* coordinate/reference labels, blueprint-style corner marks */
.ref-mark {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--ink-faint);
  letter-spacing: 0.05em;
}

/* ─── BUTTONS ───────────────────────────────────────────── */
.btn {
  display: inline-flex; align-items: center; gap: var(--sp-2);
  padding: 12px 22px; border-radius: var(--radius-sm);
  font-family: var(--font-mono); font-size: 13.5px; font-weight: 500;
  border: 1px solid transparent; transition: all var(--dur-fast) var(--ease-mech);
  white-space: nowrap;
}
.btn-primary {
  background: var(--copper); color: #fff;
}
.btn-primary:hover { background: #b8672e; transform: translateY(-1px); }
.btn-line {
  background: transparent; color: var(--ink); border-color: var(--line-strong);
}
.btn-line:hover { border-color: var(--blue); color: var(--blue); }
.btn-sm { padding: 8px 14px; font-size: 12.5px; }

/* ─── REVEAL ────────────────────────────────────────────── */
.reveal { opacity: 0; transform: translateY(16px); transition: opacity var(--dur-slow) var(--ease-mech), transform var(--dur-slow) var(--ease-mech); }
.reveal.visible { opacity: 1; transform: translateY(0); }
@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; transition: none; }
}

/* ─── SCROLLBAR ─────────────────────────────────────────── */
::-webkit-scrollbar { width: 8px; }
::-webkit-scrollbar-track { background: var(--bg); }
::-webkit-scrollbar-thumb { background: var(--line-strong); border-radius: 99px; }

/* ─── RESPONSIVE BASE ───────────────────────────────────── */
@media (max-width: 720px) {
  main > section { padding: var(--sp-7) 0; }
  .section-head { margin-bottom: var(--sp-6); }
}