.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--bg-primary);
  height: var(--nav-height);
  display: flex;
  align-items: center;
  border-bottom: 1px solid rgba(255,255,255,0.05);
  transition: background 0.3s ease, border-color 0.3s ease;
}

[data-theme="light"] .nav {
  background: rgba(239,239,239,0.92);
  border-bottom-color: rgba(0,0,0,0.08);
  backdrop-filter: blur(8px);
}

.nav__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
}

.nav__logo {
  display: flex;
  align-items: center;
  flex-shrink: 0;
}

.nav__logo svg {
  width: 100px;
  height: 13px;
}

.nav__links {
  display: flex;
  align-items: center;
  gap: 32px;
}

@keyframes underline-swim {
  0%   { background-position: 100% 100%; }
  100% { background-position: 0%   100%; }
}

.nav__links a {
  font-family: var(--font-main);
  font-weight: 400;
  font-size: 13px;
  color: var(--text-muted);
  white-space: nowrap;
  position: relative;
  transition: color var(--transition);
}

.nav__links a::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 100%;
  height: 2px;
  background-image: linear-gradient(
    to right,
    var(--accent-cyan) calc(5% - 5px),
    transparent        calc(5% - 5px),
    transparent        calc(5% + 5px),
    var(--accent-cyan) calc(5% + 5px),
    var(--accent-cyan) calc(55% - 5px),
    transparent        calc(55% - 5px),
    transparent        calc(55% + 5px),
    var(--accent-cyan) calc(55% + 5px)
  );
  background-size: 200% 2px;
  background-position: 100% 100%;
  background-repeat: no-repeat;
  opacity: 0;
}

.nav__links a:hover::after {
  opacity: 1;
  animation: underline-swim 1s linear infinite;
}

.nav__links a.active::after {
  opacity: 1;
  background-image: none;
  background-color: var(--accent-cyan);
  animation: none;
}

.nav__links a:hover,
.nav__links a.active {
  color: var(--text-primary);
}

.nav__links a.active {
  font-weight: 700;
}

.nav__links a.nav__cta {
  font-weight: 600;
}

.nav__hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  padding: 4px;
  cursor: pointer;
}

.nav__hamburger span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--text-primary);
  border-radius: 2px;
  transition: var(--transition);
}

/* Theme toggle button */
.nav__theme-toggle {
  width: 30px;
  height: 30px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-muted);
  border: 1px solid rgba(255,255,255,0.12);
  flex-shrink: 0;
  transition: color var(--transition), border-color var(--transition);
  margin-left: 8px;
}

.nav__theme-toggle:hover {
  color: var(--text-primary);
  border-color: rgba(255,255,255,0.28);
}

.nav__theme-toggle svg {
  width: 15px;
  height: 15px;
  pointer-events: none;
}

/* Dark mode: show moon, hide sun */
.nav__theme-toggle .icon-sun  { display: none; }
.nav__theme-toggle .icon-moon { display: block; }

/* Light mode: show sun, hide moon */
[data-theme="light"] .nav__theme-toggle .icon-sun  { display: block; }
[data-theme="light"] .nav__theme-toggle .icon-moon { display: none; }

[data-theme="light"] .nav__theme-toggle {
  border-color: rgba(0,0,0,0.14);
}
[data-theme="light"] .nav__theme-toggle:hover {
  border-color: rgba(0,0,0,0.3);
}

/* Mobile nav */
@media (max-width: 768px) {
  .nav__hamburger {
    display: flex;
  }

  .nav__links {
    display: none;
    position: absolute;
    top: var(--nav-height);
    left: 0;
    right: 0;
    background: var(--bg-primary);
    border-bottom: 1px solid rgba(255,255,255,0.08);
    flex-direction: column;
    align-items: flex-start;
    gap: 0;
    padding: 16px 0;
  }

  .nav__links.open {
    display: flex;
  }

  .nav__links a {
    display: block;
    width: 100%;
    padding: 12px var(--container-pad);
    font-size: 14px;
  }

  .nav__theme-toggle {
    margin: 8px var(--container-pad);
  }

  .nav__logo {
    display: none;
  }
}