/* ============================================================
   nav.css — Navigation Bar & Mobile Menu
   Depends on: tokens.css, base.css
   ============================================================ */

/* ── NAV BAR ─────────────────────────────────────────────── */
.nav-bar {
  position: fixed;
  inset: var(--s3) 0 auto;
  width: min(1200px, 92%);
  margin-inline: auto;
  left: 50%;
  transform: translateX(-50%);
  background: color-mix(in srgb, var(--bg) 78%, transparent);
  backdrop-filter: blur(20px) saturate(180%);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
  border: 1px solid var(--border);
  border-radius: var(--r-lg);
  padding: 12px 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--s5);
  box-shadow: var(--shadow-md);
  z-index: 1000;
  animation: nav-in 0.7s var(--ease-expo) both;
}
@keyframes nav-in {
  from {
    opacity: 0;
    transform: translateX(-50%) translateY(-16px);
  }
  to {
    opacity: 1;
    transform: translateX(-50%) translateY(0);
  }
}
.nav-bar.scrolled {
  background: color-mix(in srgb, var(--bg) 92%, transparent);
  box-shadow: var(--shadow-lg);
}

/* Scroll progress bar */
.scroll-track {
  position: absolute;
  bottom: 0;
  left: 12px;
  right: 12px;
  height: 2px;
  overflow: hidden;
  border-radius: var(--r-full);
}
.scroll-fill {
  width: 0%;
  height: 100%;
  background: linear-gradient(90deg, var(--accent), var(--accent-hi));
  transition: width 0.1s linear;
}

/* Logo */
.nav-logo {
  display: flex;
  align-items: center;
  gap: var(--s3);
  font-family: var(--font-display);
  font-size: 1.05rem;
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--text);
  flex-shrink: 0;
  transition: opacity var(--dur-base) ease;
}
.nav-logo:hover {
  opacity: 0.78;
}
.nav-logo img {
  border-radius: var(--r-sm);
}

/* Nav links */
.nav-links {
  display: flex;
  align-items: center;
  gap: var(--s1);
}
.nav-link {
  font-size: 0.8rem;
  font-weight: 500;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--text-muted);
  padding: 6px 12px;
  border-radius: var(--r-full);
  border: 1px solid transparent;
  transition:
    color var(--dur-base) ease,
    background var(--dur-base) ease,
    border-color var(--dur-base) ease;
}
.nav-link:hover,
.nav-link.active {
  color: var(--text);
  background: var(--surface);
  border-color: var(--border);
}

/* Nav actions group */
.nav-actions {
  display: flex;
  align-items: center;
  gap: var(--s3);
  flex-shrink: 0;
}

/* Language toggle */
.lang-toggle {
  display: flex;
  align-items: center;
  gap: 4px;
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  color: var(--text-muted);
  user-select: none;
}
.lang-opt {
  padding: 4px 6px;
  border-radius: var(--r-sm);
  cursor: pointer;
  transition: color var(--dur-base) ease;
}
.lang-opt.active {
  color: var(--accent);
}
.lang-divider {
  opacity: 0.35;
}

/* Theme toggle button */
.theme-btn {
  width: 34px;
  height: 34px;
  border-radius: 50%;
  background: var(--surface);
  border: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-muted);
  transition:
    background var(--dur-base) ease,
    color var(--dur-base) ease,
    transform var(--dur-fast) ease;
}
.theme-btn:hover {
  transform: rotate(18deg);
  color: var(--text);
  background: var(--surface-hi);
}
.theme-btn svg {
  width: 16px;
  height: 16px;
}
[data-theme="dark"] .icon-sun {
  display: block;
}
[data-theme="dark"] .icon-moon {
  display: none;
}
[data-theme="light"] .icon-sun {
  display: none;
}
[data-theme="light"] .icon-moon {
  display: block;
}
.icon-sun,
.icon-moon {
  pointer-events: none;
}

/* Hamburger */
.hamburger {
  width: 34px;
  height: 34px;
  border-radius: 50%;
  background: var(--surface);
  border: 1px solid var(--border);
  display: none;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 5px;
}
.hamburger span {
  display: block;
  width: 16px;
  height: 1.5px;
  background: var(--text);
  transition:
    transform var(--dur-base) var(--ease-expo),
    opacity var(--dur-base) ease;
  transform-origin: center;
}
.hamburger.open span:nth-child(1) {
  transform: translateY(6.5px) rotate(45deg);
}
.hamburger.open span:nth-child(2) {
  opacity: 0;
  transform: scaleX(0);
}
.hamburger.open span:nth-child(3) {
  transform: translateY(-6.5px) rotate(-45deg);
}

/* Mobile menu full-screen drawer */
.mobile-menu {
  position: fixed;
  inset: 0;
  z-index: 999;
  background: var(--bg);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-direction: column;
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--dur-slow) var(--ease-expo);
}
.mobile-menu.open {
  opacity: 1;
  pointer-events: all;
}
.mob-link {
  font-family: var(--font-display);
  font-size: clamp(2rem, 8vw, 4rem);
  font-weight: 800;
  color: var(--text-muted);
  padding: var(--s3) 0;
  display: block;
  text-align: center;
  transition: color var(--dur-base) ease;
}
.mob-link:hover {
  color: var(--accent);
}

/* Responsive breakpoints */
@media (max-width: 768px) {
  .nav-links {
    display: none;
  }
  .hamburger {
    display: flex;
  }
  .lang-toggle {
    display: none;
  }
}