/* ═══════════════════════════════════════════════════════════════════════════
   NAVIGATION — sticky, minimal, always visible

   Principle 17: Navigation must be clear and persistent
   ═══════════════════════════════════════════════════════════════════════════ */

.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: var(--z-sticky);
  height: var(--nav-height);
  background: var(--color-overlay);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
  transition: background var(--duration-normal) var(--ease-smooth),
              border-color var(--duration-normal) var(--ease-smooth);
}

.nav__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  position: relative;
  height: 100%;
  padding-left: var(--container-padding);
  padding-right: var(--container-padding);
  max-width: var(--container-wide);
  margin: 0 auto;
}

/* ── Brand ──────────────────────────────────────────────────────────────── */

.nav__brand {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  font-weight: 700;
  letter-spacing: var(--tracking-wide);
  color: var(--color-fg);
  text-decoration: none;
  text-transform: uppercase;
  transition: color var(--duration-fast) var(--ease-smooth);
}

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

.nav__brand-accent {
  color: var(--color-accent);
}

/* ── Links ──────────────────────────────────────────────────────────────── */

.nav__links {
  display: flex;
  align-items: center;
  gap: var(--space-8);
  list-style: none;
  margin: 0;
  padding: 0;
  position: absolute;
  left: 50%;
  transform: translateX(-50%);
}

.nav__link {
  font-family: var(--font-sans);
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--color-fg-muted);
  text-decoration: none;
  letter-spacing: var(--tracking-wide);
  position: relative;
  padding: var(--space-2) 0;
  transition: color var(--duration-fast) var(--ease-smooth);
}

.nav__link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 1px;
  background: var(--color-accent);
  transition: width var(--duration-normal) var(--ease-snappy);
}

.nav__link:hover,
.nav__link--active {
  color: var(--color-fg);
}

.nav__link:hover::after,
.nav__link--active::after {
  width: 100%;
}

/* ── Actions ────────────────────────────────────────────────────────────── */

.nav__actions {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

.nav__btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 2.25rem;
  height: 2.25rem;
  border: none;
  background: transparent;
  color: var(--color-fg-muted);
  cursor: pointer;
  border-radius: var(--radius-md);
  transition: color var(--duration-fast) var(--ease-smooth),
              background var(--duration-fast) var(--ease-smooth);
}

.nav__btn:hover {
  color: var(--color-fg);
  background: var(--color-bg-raised);
}

/* Theme toggle icon switching */
[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; }

/* ── Subscribe CTA ──────────────────────────────────────────────────────── */

.nav__cta {
  font-family: var(--font-sans);
  font-size: var(--text-xs);
  font-weight: 600;
  letter-spacing: var(--tracking-wide);
  color: var(--color-bg);
  background: var(--color-accent);
  padding: var(--space-2) var(--space-5);
  border-radius: var(--radius-full);
  text-decoration: none;
  transition: background var(--duration-fast) var(--ease-smooth),
              transform var(--duration-fast) var(--ease-elastic);
}

.nav__cta:hover {
  background: var(--color-accent-hover);
  color: var(--color-bg);
  transform: scale(1.03);
}

/* ── Hamburger (mobile) ─────────────────────────────────────────────────── */

.nav__hamburger {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 2.25rem;
  height: 2.25rem;
  border: none;
  background: transparent;
  cursor: pointer;
  padding: 6px;
}

.nav__hamburger-bar {
  display: block;
  width: 100%;
  height: 2px;
  background: var(--color-fg);
  border-radius: 1px;
  transition: transform var(--duration-normal) var(--ease-snappy),
              opacity var(--duration-fast) var(--ease-smooth);
}

/* Open state */
.nav__hamburger[aria-expanded="true"] .nav__hamburger-bar:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.nav__hamburger[aria-expanded="true"] .nav__hamburger-bar:nth-child(2) {
  opacity: 0;
}

.nav__hamburger[aria-expanded="true"] .nav__hamburger-bar:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* ── Mobile menu ────────────────────────────────────────────────────────── */

.nav__mobile {
  position: fixed;
  top: var(--nav-height);
  left: 0;
  right: 0;
  bottom: 0;
  background: var(--color-bg);
  padding: var(--space-12) var(--container-padding);
  display: flex;
  flex-direction: column;
  gap: var(--space-8);
  transform: translateY(-100%);
  opacity: 0;
  pointer-events: none;
  transition: transform var(--duration-slow) var(--ease-snappy),
              opacity var(--duration-normal) var(--ease-smooth);
  z-index: var(--z-overlay);
}

.nav__mobile[aria-hidden="false"] {
  transform: translateY(0);
  opacity: 1;
  pointer-events: auto;
}

.nav__mobile-links {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: var(--space-6);
}

.nav__mobile-links a {
  font-family: var(--font-display);
  font-size: var(--text-2xl);
  font-weight: 700;
  color: var(--color-fg);
  text-decoration: none;
  letter-spacing: var(--tracking-tight);
  transition: color var(--duration-fast) var(--ease-smooth);
}

.nav__mobile-links a:hover {
  color: var(--color-accent);
}

.nav__mobile-cta {
  display: inline-block;
  font-family: var(--font-sans);
  font-size: var(--text-base);
  font-weight: 600;
  color: var(--color-bg);
  background: var(--color-accent);
  padding: var(--space-4) var(--space-8);
  border-radius: var(--radius-full);
  text-decoration: none;
  text-align: center;
  transition: background var(--duration-fast) var(--ease-smooth);
  align-self: flex-start;
}

.nav__mobile-cta:hover {
  background: var(--color-accent-hover);
  color: var(--color-bg);
}

/* ── Responsive ─────────────────────────────────────────────────────────── */

@media (max-width: 48rem) {
  .nav {
    background: var(--color-bg);
    backdrop-filter: none;
    -webkit-backdrop-filter: none;
  }

  .nav__links {
    display: none;
  }

  .nav__cta {
    display: none;
  }

  .nav__hamburger {
    display: flex;
  }
}

/* ── Spacer for fixed nav ───────────────────────────────────────────────── */

.site-content {
  padding-top: var(--nav-height);
}