/* =====================================================================
   Navigation + brand + mobile menu
   ===================================================================== */

.nav {
  position: fixed;
  inset: 0 0 auto 0;
  z-index: var(--z-nav);
  transition: background var(--dur) var(--ease-out-expo),
    border-color var(--dur) var(--ease-out-expo),
    backdrop-filter var(--dur) var(--ease-out-expo);
  border-bottom: 1px solid transparent;
}
.nav.is-scrolled {
  background: oklch(13% 0.012 264 / 0.72);
  backdrop-filter: blur(14px) saturate(140%);
  border-bottom-color: var(--line);
}

.nav__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
  height: 76px;
}

/* ---- Brand ---- */
.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.7rem;
  flex-shrink: 0;
}
.brand__mark {
  display: grid;
  place-items: center;
  transition: transform var(--dur) var(--ease-spring);
}
.brand:hover .brand__mark {
  transform: rotate(-8deg) scale(1.05);
}
.brand__word {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1.18rem;
  letter-spacing: -0.01em;
  text-transform: lowercase;
}
.brand__word span {
  color: var(--text-faint);
  font-weight: 500;
}

/* ---- Desktop links ---- */
.nav__links {
  display: flex;
  align-items: center;
  gap: clamp(1rem, 0.2rem + 1.6vw, 2.4rem);
  margin-left: auto;
}
.nav__links a {
  position: relative;
  font-size: 0.92rem;
  color: var(--text-muted);
  padding: 0.4rem 0;
  transition: color var(--dur) var(--ease-out-expo);
}
.nav__links a::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -2px;
  width: 100%;
  height: 1px;
  background: var(--gradient-signal);
  transform: scaleX(0);
  transform-origin: 0 50%;
  transition: transform var(--dur) var(--ease-out-expo);
}
.nav__links a:hover {
  color: var(--text);
}
.nav__links a:hover::after {
  transform: scaleX(1);
}

.nav__cta {
  --btn-pad-y: 0.6rem;
  --btn-pad-x: 1.1rem;
  font-size: 0.9rem;
}

/* ---- Burger ---- */
.nav__burger {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 44px;
  height: 44px;
  align-items: center;
}
.nav__burger span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--text);
  border-radius: 2px;
  transition: transform var(--dur) var(--ease-out-expo),
    opacity var(--dur) var(--ease-out-expo);
}
.nav__burger[aria-expanded="true"] span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}
.nav__burger[aria-expanded="true"] span:nth-child(2) {
  opacity: 0;
}
.nav__burger[aria-expanded="true"] span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* ---- Mobile menu ---- */
.mobile-menu {
  position: fixed;
  inset: 0;
  z-index: var(--z-menu);
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 2.5rem;
  padding: var(--gutter);
  background: oklch(13% 0.012 264 / 0.96);
  backdrop-filter: blur(20px);
  opacity: 0;
  visibility: hidden;
  transform: translateY(-2%);
  transition: opacity var(--dur) var(--ease-out-expo),
    transform var(--dur) var(--ease-out-expo),
    visibility var(--dur);
}
.mobile-menu.is-open {
  opacity: 1;
  visibility: visible;
  transform: none;
}
.mobile-menu__links {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}
.mobile-menu__links a {
  display: flex;
  align-items: baseline;
  gap: 1rem;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: clamp(1.8rem, 1.2rem + 5vw, 3rem);
  letter-spacing: var(--tracking-display);
  color: var(--text);
  padding: 0.4rem 0;
  border-bottom: 1px solid var(--line-faint);
  transition: color var(--dur), padding-left var(--dur) var(--ease-out-expo);
}
.mobile-menu__links a:hover {
  color: var(--signal-bright);
  padding-left: 0.6rem;
}
.mobile-menu__links .idx {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--signal);
  letter-spacing: 0.1em;
}
.mobile-menu__cta {
  align-self: flex-start;
}

@media (max-width: 900px) {
  .nav__links,
  .nav__cta {
    display: none;
  }
  .nav__burger {
    display: flex;
  }
}