/* ==========================================================================
   Navigation Bar — Sticky with scroll-aware frosted glass transition
   ========================================================================== */

.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  height: var(--nav-height);
  display: flex;
  align-items: center;
  transition: background var(--duration-base) var(--ease-out),
              box-shadow var(--duration-base) var(--ease-out),
              backdrop-filter var(--duration-base) var(--ease-out);
}

/* Scrolled state — frosted glass */
.navbar.scrolled {
  background: var(--bg-glass);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  box-shadow: 0 1px 0 var(--border-subtle), 0 4px 24px rgba(0, 0, 0, 0.2);
}

.nav-inner {
  max-width: var(--max-width);
  width: 100%;
  margin: 0 auto;
  padding: 0 var(--space-xl);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

/* ── Logo ── */
.nav-logo {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-size: var(--text-xl);
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: -0.02em;
  z-index: 1001;
}

.nav-logo svg {
  width: 32px;
  height: 32px;
}

.nav-logo span {
  background: linear-gradient(135deg, var(--blue-300), var(--blue-500));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

/* ── Desktop Links ── */
.nav-links {
  display: flex;
  align-items: center;
  gap: var(--space-2xl);
}

.nav-links a {
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--text-secondary);
  transition: color var(--duration-fast) var(--ease-out);
  position: relative;
}

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--blue-500);
  border-radius: var(--radius-full);
  transition: width var(--duration-base) var(--ease-out);
}

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

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

/* ── GitHub Link ── */
.nav-github {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--text-secondary);
  transition: color var(--duration-fast) var(--ease-out);
}

.nav-github:hover {
  color: var(--text-primary);
}

.nav-github svg {
  width: 22px;
  height: 22px;
  fill: currentColor;
}

/* ── Mobile Hamburger ── */
.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 28px;
  height: 28px;
  z-index: 1001;
}

.nav-toggle span {
  display: block;
  width: 100%;
  height: 2px;
  background: var(--text-primary);
  border-radius: var(--radius-full);
  transition: all var(--duration-base) var(--ease-out);
  transform-origin: center;
}

/* Hamburger → X animation */
.nav-toggle.open span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

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

.nav-toggle.open span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* ── Mobile Menu Overlay ── */
.nav-mobile {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(6, 10, 20, 0.95);
  backdrop-filter: blur(24px);
  -webkit-backdrop-filter: blur(24px);
  z-index: 999;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: var(--space-2xl);
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--duration-base) var(--ease-out);
}

.nav-mobile.open {
  opacity: 1;
  pointer-events: all;
}

.nav-mobile a {
  font-size: var(--text-2xl);
  font-weight: 600;
  color: var(--text-secondary);
  transition: color var(--duration-fast) var(--ease-out);
}

.nav-mobile a:hover {
  color: var(--text-primary);
}