/* ============================================================
   layout.css — Page scaffolding: navigation, section rhythm,
   grids, and footer. Positioning and structure, not skin.
   ============================================================ */

/* Navigation */
nav.topbar {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--nav-h);
  background: rgba(13, 15, 16, 0.86);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--hairline);
}
.nav-inner {
  max-width: var(--content-max);
  margin: 0 auto;
  padding: 0 var(--content-pad);
  height: var(--nav-h);
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.logo {
  display: flex;
  align-items: center;
  gap: 11px;
  font-family: var(--font-serif);
  font-size: 19px;
  letter-spacing: 0.01em;
  cursor: pointer;
  text-decoration: none;
  flex-shrink: 0;
  white-space: nowrap;
}
.logo .logo-badge {
  height: 25px; width: auto;
  display: block;
  flex-shrink: 0;
}
.logo .dim { color: var(--paper-faint); font-size: 14px; font-family: var(--font-mono); letter-spacing: 0.05em; }

.tabs { display: flex; gap: 2px; }
.tabs button {
  font-family: var(--font-mono);
  font-size: 12.5px;
  letter-spacing: 0.04em;
  background: none; border: none;
  color: var(--paper-dim);
  padding: 10px 13px;
  cursor: pointer;
  position: relative;
  transition: color .2s ease;
  white-space: nowrap;
}
.tabs button::after {
  content: '';
  position: absolute; left: 13px; right: 13px; bottom: 5px; height: 1px;
  background: var(--copper);
  transform: scaleX(0); transform-origin: left;
  transition: transform .25s ease;
}
.tabs button:hover { color: var(--paper); }
.tabs button.active { color: var(--paper); }
.tabs button.active::after { transform: scaleX(1); }

.nav-cta {
  font-family: var(--font-mono); font-size: 12.5px; letter-spacing: 0.03em;
  background: var(--copper); color: var(--ink);
  border: none; padding: 11px 20px; cursor: pointer;
  transition: filter .18s ease; white-space: nowrap; font-weight: 500;
  text-decoration: none; display: inline-block;
}
.nav-cta:hover { filter: brightness(1.12); }

.hamburger { display: none; background: none; border: none; color: var(--paper); font-size: 22px; cursor: pointer; }

/* Reading-progress rail (width driven by scroll-progress.js) */
.scroll-progress {
  position: fixed; top: var(--nav-h); left: 0;
  height: 2px; width: 0%;
  background: var(--copper);
  z-index: 101;
  transition: width .1s linear;
}

/* Section rhythm */
section { padding: 104px 0; scroll-margin-top: var(--nav-h); }
section.tight { padding: 80px 0; }
section.alt { background: var(--ink-2); }

.section-head h2 { margin-top: 12px; max-width: 640px; }
.section-head p.lead { margin-top: 16px; }

/* Hero */
.hero { padding-top: 88px; padding-bottom: 70px; }
.hero-grid { display: grid; grid-template-columns: 1.15fr 0.85fr; gap: 60px; align-items: center; }
.hero-copy .eyebrow { margin-bottom: 26px; }
.hero h1 { margin-bottom: 22px; }
.hero-cta-row { display: flex; gap: 16px; margin-top: 38px; flex-wrap: wrap; }

/* About / Contact grids */
.about-grid { display: grid; grid-template-columns: 1.2fr 0.8fr; gap: 64px; align-items: start; }
.contact-grid { display: grid; grid-template-columns: 1.1fr 0.9fr; gap: 64px; }

/* Footer */
footer { border-top: 1px solid var(--hairline); padding: 38px 0; }
.footer-inner { display: flex; justify-content: space-between; align-items: center; flex-wrap: wrap; gap: 12px; }
.footer-inner span { font-family: var(--font-mono); font-size: 11.5px; letter-spacing: 0.03em; color: var(--paper-faint); }

@media (max-width: 860px) {
  .hero-grid, .about-grid, .contact-grid { grid-template-columns: 1fr; }
  .tabs {
    display: none;
    position: absolute; top: var(--nav-h); left: 0; right: 0;
    background: var(--ink);
    flex-direction: column;
    border-bottom: 1px solid var(--hairline);
    padding: 10px;
  }
  .tabs.open { display: flex; }
  .hamburger { display: block; }
  .nav-cta { display: none; }
}