/* C4 Protocol — shared chrome (nav + lang + mobile burger). One steel header on every page. */
:root {
  --pixel: "VT323", monospace;
  --pixel-font: var(--pixel);
  --mono: "Space Mono", monospace;
  --mono-font: var(--mono);
}

.nav {
  background: var(--surface, #12121a);
  border-bottom: 2px solid var(--border, rgba(255, 255, 255, 0.1));
  padding: 1rem 2rem;
  position: sticky;
  top: 0;
  z-index: 100;
}

.nav-inner {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
}

.logo {
  font-family: var(--pixel);
  font-size: 1.8rem;
  color: var(--gold, #c9a227);
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  white-space: nowrap;
  flex-shrink: 0;
}

.logo::before {
  content: "Φ";
  color: var(--gold, #c9a227);
  text-shadow: 0 0 10px var(--gold, #c9a227);
}

.nav-links {
  display: flex;
  gap: 1.25rem;
  list-style: none;
  margin: 0;
  padding: 0;
  flex-wrap: nowrap;
  align-items: center;
}

.nav-link {
  color: var(--text-dim, #a8a6a1);
  text-decoration: none;
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  padding: 0.45rem 0.7rem;
  border: 1px solid transparent;
  transition: color 0.2s, border-color 0.2s, background 0.2s;
  white-space: nowrap;
}

.nav-link:hover,
.nav-link.active {
  color: var(--cyan, #00e5ff);
  border-color: var(--cyan, #00e5ff);
  background: rgba(0, 229, 255, 0.1);
}

.lang-switch {
  font-family: var(--pixel);
  font-size: 1.2rem;
  flex-shrink: 0;
}

.lang-switch a {
  color: var(--text-dim, #a8a6a1);
  text-decoration: none;
  padding: 0.25rem 0.5rem;
  border: 1px solid var(--border, rgba(255, 255, 255, 0.1));
}

.lang-switch a:hover {
  color: var(--gold, #c9a227);
  border-color: var(--gold, #c9a227);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 42px;
  height: 42px;
  padding: 8px;
  background: transparent;
  border: 1px solid var(--border, rgba(255, 255, 255, 0.1));
  cursor: pointer;
  flex-shrink: 0;
  margin-left: auto;
}

.nav-toggle span {
  display: block;
  height: 2px;
  width: 100%;
  background: var(--cyan, #00e5ff);
  transition: transform 0.2s, opacity 0.2s;
}

.nav-toggle[aria-expanded="true"] span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.nav-toggle[aria-expanded="true"] span:nth-child(2) {
  opacity: 0;
}

.nav-toggle[aria-expanded="true"] span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

@media (max-width: 1100px) {
  .nav-links {
    gap: 0.5rem;
  }
  .nav-link {
    padding: 0.35rem 0.45rem;
    letter-spacing: 0.04em;
    font-size: 0.7rem;
  }
}

@media (max-width: 768px) {
  .nav-inner {
    flex-wrap: wrap;
  }
  .nav-toggle {
    display: flex;
  }
  .lang-switch {
    order: 2;
  }
  .nav-links {
    display: none;
    flex-direction: column;
    align-items: stretch;
    width: 100%;
    order: 3;
    gap: 0.35rem;
    padding: 0.75rem 0 0.25rem;
    border-top: 1px solid var(--border, rgba(255, 255, 255, 0.1));
    flex-wrap: nowrap;
  }
  .nav.is-open .nav-links {
    display: flex;
  }
  .nav-link {
    display: block;
    text-align: left;
    font-size: 0.85rem;
    padding: 0.55rem 0.75rem;
  }
}

/* Shared section rhythm (secondary pages may override .container max-width locally) */
.section {
  padding: 4rem 2rem;
}
.section-title {
  font-family: var(--pixel);
  font-size: 2rem;
  text-align: center;
  margin-bottom: 1rem;
  color: var(--gold, #c9a227);
}
.section-desc {
  text-align: center;
  color: var(--text-dim, #a8a6a1);
  max-width: 640px;
  margin: 0 auto 2rem;
  font-size: 0.95rem;
}