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

.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  height: var(--nav-height);
  display: flex;
  align-items: center;
  transition: background-color var(--duration-base) var(--ease-out),
              border-color var(--duration-base) var(--ease-out),
              backdrop-filter var(--duration-base) var(--ease-out);
  border-bottom: 1px solid transparent;
}

.nav.scrolled {
  background-color: var(--color-nav);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom-color: var(--color-border);
}

.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  max-width: var(--max-width);
  margin-inline: auto;
  padding-inline: var(--space-3);
}

@media (min-width: 768px) {
  .nav-inner {
    padding-inline: var(--space-5);
  }
}

@media (min-width: 1024px) {
  .nav-inner {
    padding-inline: var(--space-6);
  }
}

/* ---- Brand ---- */

.nav-brand {
  font-family: var(--font-heading);
  font-size: var(--text-xl);
  letter-spacing: 0.08em;
  color: var(--color-text);
  transition: color var(--duration-fast);
}

.nav-brand:hover {
  color: var(--color-accent);
}

/* ---- Links (desktop) ---- */

.nav-links {
  display: none;
  gap: var(--space-5);
  align-items: center;
}

@media (min-width: 768px) {
  .nav-links {
    display: flex;
  }
}

.nav-links a {
  font-size: var(--text-sm);
  font-weight: 400;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--color-text-muted);
  transition: color var(--duration-fast);
  position: relative;
  padding-bottom: 2px;
}

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 0;
  height: 1px;
  background: var(--color-accent);
  transition: width var(--duration-base) var(--ease-out);
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--color-text);
}

.nav-links a:hover::after,
.nav-links a.active::after {
  width: 100%;
}

/* ---- Hamburger (mobile) ---- */

.nav-toggle {
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 28px;
  height: 28px;
  cursor: pointer;
  color: var(--color-text);
}

@media (min-width: 768px) {
  .nav-toggle {
    display: none;
  }
}

.nav-toggle span {
  display: block;
  width: 100%;
  height: 1px;
  background: currentColor;
  transition: all var(--duration-base) var(--ease-out);
  transform-origin: center;
}

.nav-toggle.open span:nth-child(1) {
  transform: translateY(6px) rotate(45deg);
}

.nav-toggle.open span:nth-child(2) {
  opacity: 0;
  transform: scaleX(0);
}

.nav-toggle.open span:nth-child(3) {
  transform: translateY(-6px) rotate(-45deg);
}

/* ---- Theme toggle ---- */

.theme-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  cursor: pointer;
  color: var(--color-text-muted);
  transition: color var(--duration-fast);
  flex-shrink: 0;
}

.theme-toggle:hover {
  color: var(--color-accent);
}

.theme-toggle svg {
  width: 18px;
  height: 18px;
}

.theme-toggle .icon-moon { display: block; }
.theme-toggle .icon-sun  { display: none; }

[data-theme="light"] .theme-toggle .icon-moon { display: none; }
[data-theme="light"] .theme-toggle .icon-sun  { display: block; }

/* ---- Mobile menu ---- */

.nav-mobile {
  position: fixed;
  top: var(--nav-height);
  left: 0;
  right: 0;
  bottom: 0;
  background: var(--color-bg);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: var(--space-5);
  z-index: 99;
  opacity: 0;
  pointer-events: none;
  transform: translateY(-8px);
  transition: all var(--duration-base) var(--ease-out);
}

.nav-mobile.open {
  opacity: 1;
  pointer-events: all;
  transform: translateY(0);
}

.nav-mobile a {
  font-family: var(--font-heading);
  font-size: var(--text-3xl);
  color: var(--color-text-muted);
  transition: color var(--duration-fast);
}

.nav-mobile a:hover,
.nav-mobile a.active {
  color: var(--color-accent);
}