/* ─── HEADER ─── */
#vm-header {
  position: fixed; top: 0; left: 0; right: 0; z-index: 200;
  background: color-mix(in srgb, var(--bg) 85%, transparent);
  backdrop-filter: blur(16px) saturate(180%);
  -webkit-backdrop-filter: blur(16px) saturate(180%);
  border-bottom: 1px solid var(--border-light);
  transition: background 0.3s ease, border-color 0.3s ease, box-shadow 0.3s ease;
}
#vm-header.scrolled {
  box-shadow: var(--shadow);
  background: color-mix(in srgb, var(--bg) 95%, transparent);
}

.header-inner {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  padding: 0 3.5rem;
  height: 68px;
}

/* ─── LOGO ─── */
.header-logo {
  display: flex; align-items: center; gap: 0.6rem;
  text-decoration: none;
}
.logo-mark {
  width: 28px; height: 28px;
  background: var(--fg);
  clip-path: polygon(50% 0%, 100% 50%, 50% 100%, 0% 50%);
  transition: background 0.3s ease, transform 0.3s ease;
  flex-shrink: 0;
}
.header-logo:hover .logo-mark { transform: rotate(45deg); }
.logo-text {
  font-family: var(--font-display);
  font-size: 1.25rem;
  letter-spacing: 0.12em;
  color: var(--fg);
  line-height: 1;
}
.logo-sub {
  font-family: var(--font-mono);
  font-size: 0.52rem;
  letter-spacing: 0.2em;
  color: var(--fg-subtle);
  text-transform: uppercase;
  display: block;
  margin-top: 1px;
}

/* ─── NAV ─── */
.header-nav {
  display: flex; align-items: center; gap: 0;
}
.nav-item {
  position: relative;
  text-decoration: none;
  color: var(--fg-muted);
  font-size: 0.78rem;
  font-weight: 400;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: 0.5rem 1.1rem;
  transition: color 0.2s ease;
  font-family: var(--font-body);
}
.nav-item::after {
  content: '';
  position: absolute;
  bottom: -1px; left: 50%; right: 50%;
  height: 1px;
  background: var(--fg);
  transition: left 0.25s ease, right 0.25s ease;
}
.nav-item:hover { color: var(--fg); }
.nav-item:hover::after,
.nav-item.active::after { left: 1.1rem; right: 1.1rem; }
.nav-item.active { color: var(--fg); }

/* ─── RIGHT SIDE ─── */
.header-right {
  display: flex; align-items: center; gap: 1rem;
  justify-content: flex-end;
}

/* ─── THEME TOGGLE ─── */
.theme-toggle {
  display: flex; align-items: center; gap: 0.5rem;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: 100px;
  padding: 0.3rem 0.5rem;
  cursor: none;
  transition: background 0.2s, border-color 0.2s;
}
.theme-toggle:hover { border-color: var(--fg-muted); }
.toggle-icon {
  font-size: 0.75rem;
  width: 20px; height: 20px;
  display: flex; align-items: center; justify-content: center;
  border-radius: 50%;
  transition: background 0.2s, opacity 0.2s;
  line-height: 1;
}
.toggle-icon.active {
  background: var(--fg);
  filter: invert(1);
}
.toggle-track {
  width: 32px; height: 18px;
  background: var(--border);
  border-radius: 100px;
  position: relative;
  transition: background 0.25s ease;
  cursor: none;
}
.toggle-track.dark { background: var(--fg-muted); }
.toggle-thumb {
  width: 12px; height: 12px;
  background: var(--bg);
  border-radius: 50%;
  position: absolute;
  top: 3px; left: 3px;
  transition: transform 0.25s ease, background 0.25s ease;
  box-shadow: 0 1px 3px rgba(0,0,0,0.2);
}
.toggle-track.dark .toggle-thumb { transform: translateX(14px); background: var(--bg); }

/* ─── CTA BUTTON ─── */
.header-cta {
  display: inline-flex; align-items: center; gap: 0.5rem;
  background: var(--fg);
  color: var(--bg);
  padding: 0.5rem 1.1rem;
  font-family: var(--font-body);
  font-size: 0.72rem;
  font-weight: 500;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  text-decoration: none;
  border-radius: 2px;
  transition: opacity 0.2s ease;
  white-space: nowrap;
}
.header-cta:hover { opacity: 0.8; }

/* ─── MOBILE HAMBURGER ─── */
.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  padding: 0.4rem;
  cursor: none;
  background: none;
  border: none;
}
.ham-line {
  width: 22px; height: 1.5px;
  background: var(--fg);
  transition: transform 0.3s ease, opacity 0.3s ease;
}
.hamburger.open .ham-line:nth-child(1) { transform: translateY(6.5px) rotate(45deg); }
.hamburger.open .ham-line:nth-child(2) { opacity: 0; }
.hamburger.open .ham-line:nth-child(3) { transform: translateY(-6.5px) rotate(-45deg); }

/* ─── MOBILE MENU ─── */
.mobile-menu {
  display: none;
  position: fixed; top: 68px; left: 0; right: 0; bottom: 0;
  background: var(--bg);
  z-index: 199;
  padding: 2rem 2rem;
  flex-direction: column;
  gap: 0;
  border-top: 1px solid var(--border-light);
  overflow-y: auto;
}
.mobile-menu.open { display: flex; }
.mobile-nav-item {
  font-family: var(--font-display);
  font-size: 2.5rem;
  letter-spacing: 0.05em;
  color: var(--fg);
  text-decoration: none;
  padding: 1rem 0;
  border-bottom: 1px solid var(--border-light);
  transition: padding 0.2s ease, color 0.2s ease;
  display: flex; justify-content: space-between; align-items: center;
}
.mobile-nav-item:hover { padding-left: 0.5rem; color: var(--fg-muted); }
.mobile-menu-footer {
  margin-top: auto;
  padding-top: 2rem;
  font-family: var(--font-mono);
  font-size: 0.65rem;
  color: var(--fg-subtle);
  letter-spacing: 0.15em;
  text-transform: uppercase;
}

@media (max-width: 900px) {
  .header-inner { grid-template-columns: 1fr auto; padding: 0 1.5rem; }
  .header-nav, .header-right .header-cta { display: none; }
  .hamburger { display: flex; }
  .header-right { gap: 0.5rem; }
  .theme-toggle { padding: 0.25rem 0.4rem; }
}