/* ── Scroll progress bar ── */
.scroll-progress {
  position: fixed;
  top: 0;
  left: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--color-accent), var(--color-accent-200));
  z-index: 101;
  width: 0%;
  transition: none;
}

/* ── Top navigation ── */
.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--nav-height);
  background: rgba(250, 250, 250, 0.8);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border-subtle);
  transition: background 0.3s ease, box-shadow 0.3s ease;
}
.nav__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
  max-width: var(--container-wide);
  margin: 0 auto;
  padding: 0 var(--space-6);
}

.logo {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  text-decoration: none;
  color: var(--color-text);
}
.logo__mark { width: 34px; height: 34px; flex: none; display: block; }
.logo__mark svg { width: 100%; height: 100%; display: block; }
.logo__text {
  font-family: var(--font-sans);
  font-weight: 800;
  font-size: 1.0625rem;
  letter-spacing: -0.02em;
  color: inherit;
  white-space: nowrap;
}
.logo__ia { color: var(--color-accent); }
.logo--light { color: #fff; }

.nav__links {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  list-style: none;
}
.nav__link {
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--color-text-secondary);
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius-sm);
  transition: all var(--duration-fast) var(--ease-out);
  text-decoration: none;
  position: relative;
}
.nav__link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 50%;
  width: 0;
  height: 2px;
  background: var(--color-accent);
  border-radius: 1px;
  transition: width 0.25s var(--ease-out), left 0.25s var(--ease-out);
}
.nav__link:hover {
  color: var(--color-text);
}
.nav__link:hover::after {
  width: 60%;
  left: 20%;
}
.nav__link--active {
  color: var(--color-accent);
  font-weight: 600;
}

.nav__cta {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

/* ── Mobile toggle ── */
.nav__toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  width: 24px;
  cursor: pointer;
  padding: var(--space-2);
}
.nav__toggle span {
  display: block;
  height: 2px;
  background: var(--color-text);
  border-radius: 1px;
  transition: all var(--duration-fast) var(--ease-out);
}

/* ── Mobile menu (fullscreen overlay) ── */
.nav__mobile {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 99;
  background: var(--color-bg);
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: var(--space-8);
}
.nav__mobile.is-open { display: flex; }
.nav__mobile a {
  font-size: var(--text-2xl);
  font-weight: 600;
  color: var(--color-text);
  text-decoration: none;
}
.nav__mobile a:hover { color: var(--color-accent); }
.nav__mobile-close {
  position: absolute;
  top: var(--space-6);
  right: var(--space-6);
  font-size: var(--text-2xl);
  color: var(--color-text-secondary);
  cursor: pointer;
}

@media (max-width: 900px) {
  .nav__links { display: none; }
  .nav__cta .btn { display: none; }
  .nav__toggle { display: flex; }
}