/* ============================================
   NAVIGATION
============================================ */

.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: var(--color-paper);
  border-bottom: 1px solid transparent;
  transition: border-color var(--transition-base), box-shadow var(--transition-base), background var(--transition-base);
}

.site-header.scrolled {
  border-bottom-color: var(--color-paper-3);
  box-shadow: var(--shadow-sm);
}

.header-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-lg);
  height: var(--nav-height);
  display: flex;
  align-items: center;
  gap: var(--space-lg);
}

/* Logo */
.logo {
  font-family: var(--font-display);
  font-size: 1.05rem;
  font-weight: 500;
  letter-spacing: 0.18em;
  color: var(--color-ink);
  white-space: nowrap;
  flex-shrink: 0;
  transition: opacity var(--transition-fast);
}
.logo:hover { opacity: 0.7; }

/* Desktop Nav */
.main-nav {
  display: flex;
  align-items: center;
  gap: var(--space-lg);
  margin-left: auto;
}

.main-nav a {
  font-size: var(--text-sm);
  font-weight: 400;
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
  position: relative;
  transition: color var(--transition-fast);
}

.main-nav a::after {
  content: '';
  position: absolute;
  bottom: -3px;
  left: 0;
  right: 0;
  height: 1px;
  background: var(--color-accent);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform var(--transition-base);
}

.main-nav a:hover {
  color: var(--color-ink);
}
.main-nav a:hover::after {
  transform: scaleX(1);
}

/* Last nav item — styled like a button */
.main-nav a:last-child {
  color: var(--color-accent);
  font-weight: 500;
  border: 1px solid var(--color-accent);
  padding: 0.4rem 1rem;
  border-radius: var(--radius-pill);
  letter-spacing: 0.08em;
}
.main-nav a:last-child::after { display: none; }
.main-nav a:last-child:hover {
  background: var(--color-accent);
  color: var(--color-white);
}

/* Mobile Toggle */
.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 6px;
  margin-left: auto;
}
.nav-toggle span {
  display: block;
  width: 22px;
  height: 1.5px;
  background: var(--color-ink);
  transition: transform var(--transition-base), opacity var(--transition-base);
}

/* Mobile Nav */
.mobile-nav {
  display: none;
  flex-direction: column;
  padding: var(--space-md) var(--space-lg) var(--space-lg);
  background: var(--color-paper);
  border-top: 1px solid var(--color-paper-3);
  gap: var(--space-md);
}

.mobile-nav a {
  font-size: var(--text-md);
  font-weight: 300;
  color: var(--color-ink-muted);
  letter-spacing: 0.04em;
  border-bottom: 1px solid var(--color-paper-2);
  padding-bottom: var(--space-md);
}
.mobile-nav a:last-child { border-bottom: none; }

.mobile-nav.open {
  display: flex;
}

/* Responsive */
@media (max-width: 860px) {
  .main-nav { display: none; }
  .nav-toggle { display: flex; }
}