/* ============================================================
   NAVIGATION — Sticky Nav with Underline Hover
   ============================================================ */

.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  height: var(--nav-height);
  background-color: var(--color-bg-primary);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  transition:
    background-color var(--duration-base),
    box-shadow var(--duration-base),
    border-color var(--duration-base);
  border-bottom: 1px solid transparent;
}

[data-theme="light"] .nav {
  background-color: rgba(255,255,255,0.92);
}

[data-theme="dark"] .nav {
  background-color: rgba(10,10,10,0.92);
}

.nav.scrolled {
  border-bottom-color: var(--color-border);
  box-shadow: var(--shadow-sm);
}

/* ── Nav Inner ───────────────────────────────────────────── */
.nav__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
  max-width: var(--max-width);
  margin-inline: auto;
  padding-inline: clamp(1.5rem, 5vw, 6rem);
  gap: var(--space-4);
}

/* ── Logo ────────────────────────────────────────────────── */
.nav__logo {
  font-size: var(--text-md);
  font-weight: var(--weight-bold);
  letter-spacing: var(--tracking-tight);
  color: var(--color-text-primary);
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: var(--space-2);
  transition: opacity var(--duration-fast);
  flex-shrink: 0;
}

.nav__logo:hover { opacity: 0.6; }

.nav__logo-mark {
  width: 28px;
  height: 28px;
  border-radius: var(--radius-sm);
  background-color: var(--color-text-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background-color var(--duration-base);
}

.nav__logo-mark span {
  color: var(--color-bg-primary);
  font-size: 12px;
  font-weight: var(--weight-black);
  letter-spacing: 0;
}

/* ── Nav Links ───────────────────────────────────────────── */
.nav__links {
  display: flex;
  align-items: center;
  gap: clamp(var(--space-6), 2.5vw, var(--space-10));
}

.nav__link {
  position: relative;
  font-size: var(--text-sm);
  font-weight: var(--weight-medium);
  color: var(--color-text-secondary);
  text-decoration: none;
  letter-spacing: -0.01em;
  padding-block: var(--space-2);
  transition: color var(--duration-fast);
}

.nav__link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 1px;
  background-color: var(--color-text-primary);
  transition: width var(--duration-base);
}

.nav__link:hover { color: var(--color-text-primary); }
.nav__link:hover::after,
.nav__link.active::after { width: 100%; }
.nav__link.active { color: var(--color-text-primary); }

/* ── Nav CTA ─────────────────────────────────────────────── */
.nav__cta {
  font-size: var(--text-sm);
  font-weight: var(--weight-semibold);
  padding: var(--space-2) var(--space-5);
  border: 1px solid var(--color-text-primary);
  border-radius: var(--radius-full);
  color: var(--color-text-primary);
  background: transparent;
  cursor: pointer;
  text-decoration: none;
  white-space: nowrap;
  transition:
    background-color var(--duration-fast),
    color var(--duration-fast),
    border-color var(--duration-base);
}

.nav__cta:hover {
  background-color: var(--color-text-primary);
  color: var(--color-bg-primary);
}

/* ── Mobile Menu Button ──────────────────────────────────── */
.nav__burger {
  display: none;
  flex-direction: column;
  gap: 5px;
  padding: var(--space-2);
  cursor: pointer;
  background: none;
  border: none;
}

.nav__burger span {
  display: block;
  width: 22px;
  height: 1.5px;
  background-color: var(--color-text-primary);
  transition: transform var(--duration-base), opacity var(--duration-base);
  transform-origin: center;
}

.nav__burger.open span:nth-child(1) { transform: translateY(6.5px) rotate(45deg); }
.nav__burger.open span:nth-child(2) { opacity: 0; transform: scaleX(0); }
.nav__burger.open span:nth-child(3) { transform: translateY(-6.5px) rotate(-45deg); }

/* ── Mobile Drawer ───────────────────────────────────────── */
.nav__drawer {
  display: none;
  position: fixed;
  top: var(--nav-height);
  left: 0;
  right: 0;
  bottom: 0;
  background-color: var(--color-bg-primary);
  z-index: 999;
  padding: var(--space-8) clamp(1.5rem, 5vw, 6rem);
  flex-direction: column;
  gap: var(--space-2);
  transform: translateY(-10px);
  opacity: 0;
  transition:
    transform var(--duration-slow),
    opacity var(--duration-slow),
    background-color var(--duration-base);
  pointer-events: none;
  border-top: 1px solid var(--color-border);
  overflow-y: auto;
}

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

.nav__drawer-link {
  font-size: var(--text-2xl);
  font-weight: var(--weight-bold);
  letter-spacing: var(--tracking-tight);
  color: var(--color-text-primary);
  text-decoration: none;
  padding-block: var(--space-3);
  border-bottom: 1px solid var(--color-border);
  transition: color var(--duration-fast);
}

.nav__drawer-link:hover { color: var(--color-text-secondary); }

/* ── Page Top Padding ────────────────────────────────────── */
.page-offset { padding-top: var(--nav-height); }

/* ── Responsive ──────────────────────────────────────────── */
@media (max-width: 900px) {
  .nav__links { display: none; }
  .nav__cta   { display: none; }
  .nav__burger { display: flex; }
  .nav__drawer { display: flex; }
}