.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255,255,255,0.85);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--c-line);
  transition: background var(--t-base), border-color var(--t-base);
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 18px 24px;
}
.logo {
  display: flex;
  align-items: center;
}
.logo img {
  height: 48px;
  width: auto;
  display: block;
}
.logo-mark {
  font-family: var(--f-display);
  font-weight: 600;
  font-size: 1.625rem;
  letter-spacing: -0.02em;
  color: var(--c-purple-deep);
}
.logo-sub {
  font-family: var(--f-body);
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.22em;
  color: var(--c-text-faint);
}
.primary-nav {
  display: flex;
  gap: var(--sp-7);
}
.primary-nav a {
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--c-text);
  transition: color var(--t-fast);
  position: relative;
  padding: 4px 0;
}
.primary-nav a:hover { color: var(--c-purple); }
.primary-nav a::after {
  content: '';
  position: absolute;
  left: 0; bottom: -2px;
  width: 0; height: 2px;
  background: var(--c-purple);
  transition: width var(--t-base);
}
.primary-nav a:hover::after { width: 100%; }

/* Mobile menu toggle */
.nav-toggle {
  display: none;
  width: 40px;
  height: 40px;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 5px;
  border-radius: var(--r-pill);
  transition: background var(--t-fast);
}
.nav-toggle:hover { background: var(--c-purple-soft); }
.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--c-text);
  transition: transform var(--t-base), opacity var(--t-base);
}
.site-header.menu-open .nav-toggle span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.site-header.menu-open .nav-toggle span:nth-child(2) { opacity: 0; }
.site-header.menu-open .nav-toggle span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

.mobile-nav {
  display: none;
  flex-direction: column;
  gap: var(--sp-3);
  padding: 0 24px 24px;
  border-top: 1px solid var(--c-line);
}
.mobile-nav a {
  font-size: 1.05rem;
  font-weight: 500;
  padding: 12px 0;
  border-bottom: 1px solid var(--c-line-soft);
}
.mobile-nav a:last-child {
  border-bottom: 0;
  margin-top: var(--sp-3);
  text-align: center;
}
.site-header.menu-open .mobile-nav {
  display: flex;
}

@media (max-width: 820px) {
  .primary-nav { display: none; }
  .desktop-cta { display: none; }
  .nav-toggle { display: flex; }
  .header-inner { padding: 14px 20px; }
  .logo-mark { font-size: 1.4rem; }
}