nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 800;
  padding: 32px 60px; display: flex; align-items: center; justify-content: space-between;
  opacity: 0; transition: opacity 0.6s ease, padding 0.4s ease, background 0.4s ease, border-color 0.4s ease;
  border-bottom: 1px solid transparent;
}
nav.vis { opacity: 1; }
nav.scrolled { padding: 20px 60px; background: var(--bg); border-bottom-color: var(--line); }

.nav-logo { font-family: 'Bebas Neue', sans-serif; font-size: 28px; letter-spacing: 0.08em; color: var(--text); transition: color 0.5s; }
.nav-center { display: flex; gap: 44px; list-style: none; }
.nav-center a {
  font-family: 'Space Mono', monospace; font-size: 10px; letter-spacing: 0.16em;
  text-transform: uppercase; color: var(--muted); position: relative; transition: color 0.35s;
}
.nav-center a::after {
  content: ''; position: absolute; bottom: -3px; left: 0; height: 1px; width: 0;
  background: var(--accent); transition: width 0.35s ease;
}
.nav-center a:hover { color: var(--text); }
.nav-center a:hover::after { width: 100%; }
.nav-center a.active { color: var(--text); }
.nav-center a.active::after { width: 100%; }

.toggle {
  display: flex; align-items: center; gap: 10px; background: none; border: none;
  font-family: 'Space Mono', monospace; font-size: 9px; letter-spacing: 0.16em; text-transform: uppercase;
  color: var(--muted); transition: color 0.3s;
}
.toggle:hover { color: var(--text); }
.toggle-pill {
  width: 42px; height: 22px; border: 1px solid var(--line2); border-radius: 11px;
  position: relative; background: var(--bg2); transition: background 0.4s, border-color 0.4s;
}
.toggle-dot {
  position: absolute; top: 3px; left: 3px; width: 14px; height: 14px; border-radius: 50%;
  background: var(--muted); transition: transform 0.4s cubic-bezier(0.34,1.56,0.64,1), background 0.4s;
}
[data-theme="light"] .toggle-dot { transform: translateX(20px); background: var(--text); }
.toggle:hover .toggle-dot { background: var(--accent); }
.toggle-key {
  display: flex; align-items: center; justify-content: center;
  width: 16px; height: 16px; border: 1px solid var(--line2); border-radius: 3px;
  font-size: 8px; letter-spacing: 0; color: var(--dim); transition: border-color 0.3s, color 0.3s;
}
.toggle:hover .toggle-key { border-color: var(--dim); color: var(--muted); }

.nav-right { display: flex; align-items: center; gap: 28px; }

/* Mobile hamburger — hidden on desktop */
.nav-burger {
  display: none; flex-direction: column; justify-content: center; gap: 5px;
  width: 32px; height: 32px; background: none; border: none; padding: 0;
  cursor: pointer; position: relative; z-index: 950;
}
.nav-burger span {
  display: block; width: 100%; height: 1.5px; background: var(--text);
  transition: transform 0.35s cubic-bezier(0.16,1,0.3,1), opacity 0.25s ease, background 0.5s;
}
.nav-burger[aria-expanded="true"] span:nth-child(1) { transform: translateY(6.5px) rotate(45deg); }
.nav-burger[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.nav-burger[aria-expanded="true"] span:nth-child(3) { transform: translateY(-6.5px) rotate(-45deg); }

/* Mobile slide-down menu */
.mobile-menu {
  position: fixed; top: 0; right: 0; height: 100svh; width: min(320px, 78vw);
  background: var(--bg); z-index: 900; border-left: 1px solid var(--line);
  transform: translateX(100%); transition: transform 0.45s cubic-bezier(0.16,1,0.3,1), background 0.5s, border-color 0.5s;
  display: flex; align-items: center; padding: 0 44px;
}
.mobile-menu.open { transform: translateX(0); }
.mobile-menu-list { list-style: none; display: flex; flex-direction: column; gap: 26px; width: 100%; }
.mobile-menu-list a {
  font-family: 'Bebas Neue', sans-serif; font-size: clamp(28px, 8vw, 42px);
  letter-spacing: 0.04em; color: var(--text); transition: color 0.3s, letter-spacing 0.3s;
}
.mobile-menu-list a:hover, .mobile-menu-list a:active { letter-spacing: 0.07em; color: var(--accent); }
.mobile-menu-list a.active { color: var(--accent); letter-spacing: 0.07em; }
.mobile-menu-backdrop {
  position: fixed; inset: 0; background: rgba(0,0,0,0.5); z-index: 890;
  opacity: 0; pointer-events: none; transition: opacity 0.4s ease;
}
.mobile-menu-backdrop.show { opacity: 1; pointer-events: auto; }