.nav {
  position: fixed;
  top: 1rem;
  left: 50%;
  z-index: 20;
  display: flex;
  flex-direction: column;
  width: min(11.5rem, calc(100vw - 2rem));
  padding: 0.35rem;
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: 0.85rem;
  background: rgba(12, 12, 12, 0.45);
  box-shadow: 0 10px 40px rgba(0, 0, 0, 0.28);
  backdrop-filter: blur(18px) saturate(1.2);
  -webkit-backdrop-filter: blur(18px) saturate(1.2);
  transform: translateX(-50%);
  transition: width 0.55s cubic-bezier(0.65, 0, 0.35, 1);
}

.nav.is-open {
  width: min(16.5rem, calc(100vw - 2rem));
}

.nav__bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 2.4rem;
  padding-left: 0.6rem;
}

.nav__brand {
  display: inline-flex;
  align-items: center;
  color: #fff;
  text-decoration: none;
}

.nav__mark {
  display: block;
  width: 1.15rem;
  height: 1.15rem;
}

.nav__menu {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  width: 2.35rem;
  height: 2.35rem;
  border: none;
  border-radius: 0.55rem;
  background: rgba(0, 0, 0, 0.35);
  cursor: pointer;
}

.nav__menu-lines {
  --menu-spread: 2.75px;
  display: block;
  width: 1.15rem;
  height: 1.15rem;
  overflow: visible;
  transition: transform 0.6s cubic-bezier(0.65, 0, 0.35, 1);
}

.nav__menu-line {
  stroke: #fff;
  stroke-width: 0.9;
  stroke-linecap: round;
  vector-effect: non-scaling-stroke;
  transform-origin: 8px 8px;
  transition: transform 0.4s cubic-bezier(0.65, 0, 0.35, 1);
}

.nav__menu-line--a {
  transform: translateY(calc(var(--menu-spread) * -1));
}

.nav__menu-line--b {
  transform: translateY(var(--menu-spread));
}

/* closed hover: merge to one line — same stroke, same length */
@media (hover: hover) {
  .nav:not(.is-open):not(.is-closing) .nav__menu:hover .nav__menu-line--a,
  .nav:not(.is-open):not(.is-closing) .nav__menu:hover .nav__menu-line--b {
    transform: none;
  }
}

/* open: spin 360°, same 2 lines split into X */
.nav.is-open .nav__menu-lines {
  transform: rotate(360deg);
}

.nav.is-open .nav__menu-line--a {
  transform: rotate(45deg);
  transition-delay: 0.22s;
}

.nav.is-open .nav__menu-line--b {
  transform: rotate(-45deg);
  transition-delay: 0.22s;
}

/* close: reverse spin, X → one line, then apart */
.nav.is-closing .nav__menu-lines {
  animation: nav-spin-reverse 0.6s cubic-bezier(0.65, 0, 0.35, 1) forwards;
}

.nav.is-closing .nav__menu-line--a,
.nav.is-closing .nav__menu-line--b {
  transition-delay: 0s;
  transform: none;
}

@keyframes nav-spin-reverse {
  from {
    transform: rotate(360deg);
  }
  to {
    transform: rotate(0deg);
  }
}

.nav__panel {
  display: grid;
  grid-template-rows: 0fr;
  transition: grid-template-rows 0.55s cubic-bezier(0.65, 0, 0.35, 1);
}

.nav.is-open .nav__panel {
  grid-template-rows: 1fr;
}

.nav__panel-inner {
  overflow: hidden;
}

.nav__links {
  --link-h: 2.45rem;
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  margin-top: 0.35rem;
  padding: 0.15rem;
}

.nav__link {
  display: flex;
  align-items: stretch;
  gap: 0.3rem;
  overflow: hidden;
  height: var(--link-h);
  color: rgba(255, 255, 255, 0.92);
  text-decoration: none;
  opacity: 0;
  transform: translateY(-0.45rem);
  transition:
    opacity 0.35s cubic-bezier(0.22, 1, 0.36, 1),
    transform 0.4s cubic-bezier(0.22, 1, 0.36, 1);
}

.nav__link-square {
  display: flex;
  align-items: center;
  justify-content: center;
  flex: 0 0 var(--link-h);
  width: var(--link-h);
  height: var(--link-h);
  margin-left: calc(-1 * var(--link-h) - 0.3rem);
  border-radius: 0.55rem;
  background: rgba(0, 0, 0, 0.35);
  color: #fff;
  transform: translateX(-0.4rem);
  transition:
    margin-left 0.4s cubic-bezier(0.65, 0, 0.35, 1),
    transform 0.4s cubic-bezier(0.65, 0, 0.35, 1);
}

.nav__link-square svg {
  display: block;
  width: 0.85rem;
  height: 0.85rem;
}

.nav__link-label {
  display: flex;
  flex: 1;
  align-items: center;
  min-width: 0;
  padding: 0 0.9rem;
  border-radius: 0.55rem;
  background: rgba(0, 0, 0, 0.35);
  font-size: 0.82rem;
  font-weight: 300;
  letter-spacing: 0.02em;
}

.nav.is-open .nav__link {
  opacity: 1;
  transform: none;
}

.nav.is-open .nav__link:nth-child(1) {
  transition-delay: 0.1s;
}

.nav.is-open .nav__link:nth-child(2) {
  transition-delay: 0.16s;
}

.nav.is-open .nav__link:nth-child(3) {
  transition-delay: 0.22s;
}

.nav:not(.is-open) .nav__link {
  opacity: 0;
  transform: translateY(-0.45rem);
  transition-delay: 0s;
}

@media (hover: hover) {
  .nav__link:hover .nav__link-square {
    margin-left: 0;
    transform: none;
  }
}