.hero {
  --window-base: clamp(0.6rem, 1.3vw, 1.15rem);
  --tower-max: clamp(12rem, 44svh, 36rem);

  position: relative;
  overflow: hidden;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  min-height: 100svh;
  padding: var(--top-space) 0 calc(var(--tower-max) * 0.5);
  background: linear-gradient(to bottom, var(--sky-top), var(--sky-bottom));
}

.hero::after {
  content: "";
  position: absolute;
  right: 0;
  bottom: 0;
  left: 0;
  z-index: 1;
  height: clamp(7rem, 22svh, 12rem);
  pointer-events: none;
  background: linear-gradient(
    to bottom,
    transparent,
    color-mix(in srgb, var(--color-surface-muted) 60%, transparent) 55%,
    var(--color-surface-muted)
  );
}

.hero__inner {
  position: relative;
  z-index: 2;
}

.hero__inner::before {
  content: "";
  position: absolute;
  inset: -3rem -5rem;
  z-index: -1;
  background: radial-gradient(closest-side, var(--hero-scrim), transparent);
}

.night-sky {
  position: absolute;
  inset: 0;
  overflow: hidden;
  pointer-events: none;
}

.night-sky__stars {
  transform: translate(calc(var(--px, 0) * -14px), calc(var(--py, 0) * -8px));
  transition: transform 0.7s ease-out;
}

.night-sky__moon {
  transform: translate(calc(var(--px, 0) * -26px), calc(var(--py, 0) * -16px));
  transition: transform 0.6s ease-out;
}

.night__layer--back {
  transform: translate(calc(var(--px, 0) * -12px), calc(var(--py, 0) * -4px));
  transition: transform 0.5s ease-out;
}

.night__layer--front {
  transform: translate(calc(var(--px, 0) * -26px), calc(var(--py, 0) * -8px));
  transition: transform 0.4s ease-out;
}

.hero__inner {
  transform: translate(calc(var(--px, 0) * -5px), calc(var(--py, 0) * -3px));
  transition: transform 0.6s ease-out;
}

.night-sky__glow {
  position: absolute;
  inset: 0;
  background: radial-gradient(circle 24rem at var(--mx, 50%) var(--my, 40%), var(--window-glow), transparent 70%);
  opacity: calc(var(--glow, 0) * 0.35);
  transition: opacity 0.5s ease;
}

.night-sky__stars {
  position: absolute;
  inset: 0;
}

.night-sky__star {
  position: absolute;
  width: var(--size);
  height: var(--size);
  border-radius: 50%;
  background-color: #fff4e0;
  opacity: calc(var(--stars-opacity) * var(--alpha));
  animation: twinkle var(--duration) ease-in-out var(--delay) infinite alternate;
}

@keyframes twinkle {
  from { opacity: calc(var(--stars-opacity) * 0.15); }
  to   { opacity: calc(var(--stars-opacity) * var(--alpha)); }
}

.night-sky__aurora {
  position: absolute;
  inset: 0 0 30% 0;
  opacity: var(--aurora-opacity, 0);
  mix-blend-mode: screen;
  filter: blur(28px);
  background:
    radial-gradient(ellipse 60% 40% at 25% 30%, rgb(94 234 180 / 0.55), transparent 70%),
    radial-gradient(ellipse 55% 35% at 65% 22%, rgb(130 120 255 / 0.45), transparent 70%),
    radial-gradient(ellipse 45% 30% at 85% 38%, rgb(94 234 212 / 0.4), transparent 70%);
  animation: aurora-drift 26s ease-in-out infinite alternate;
  transition: opacity 0.8s ease;
}

@keyframes aurora-drift {
  from { transform: translateX(-4%) skewX(-4deg) scaleY(1); }
  to   { transform: translateX(5%) skewX(5deg) scaleY(1.15); }
}

.night-sky__moon {
  position: absolute;
  top: calc(var(--top-space) + 1rem);
  right: 8%;
  width: clamp(3.5rem, 7vw, 6.5rem);
  aspect-ratio: 1;
  border-radius: 50%;
  background: radial-gradient(circle at 35% 35%, #fffaf0, var(--moon) 70%);
  box-shadow: 0 0 4rem 1rem var(--moon-glow);
}

.night-sky__cloud {
  position: absolute;
  left: -30rem;
  width: 28rem;
  height: 7rem;
  border-radius: 50%;
  background-color: var(--cloud);
  filter: blur(26px);
  animation: drift var(--duration) linear var(--delay) infinite;
}

.night-sky__cloud--1 { top: 22%; --duration: 130s; --delay: -40s; }
.night-sky__cloud--2 { top: 36%; --duration: 170s; --delay: -110s; width: 36rem; height: 9rem; }
.night-sky__cloud--3 { top: 14%; --duration: 210s; --delay: -15s; }

@keyframes drift {
  from { transform: translateX(0); }
  to   { transform: translateX(calc(100vw + 32rem)); }
}

.night-sky__shooting {
  position: absolute;
  width: var(--length, 7rem);
  height: 2px;
  background: linear-gradient(90deg, transparent, var(--moon));
  border-radius: 2px;
  box-shadow: 0 0 0.6rem var(--moon);
  opacity: 0;
  transform: scaleX(var(--flip, 1)) rotate(var(--angle, 22deg));
  animation: shoot var(--duration, 1.3s) ease-out forwards;
}

@keyframes shoot {
  0%   { opacity: 0;   translate: 0 0; }
  12%  { opacity: 1; }
  100% { opacity: 0;   translate: calc(var(--dx, 22rem) * var(--flip, 1)) var(--dy, 9rem); }
}

.night {
  position: absolute;
  right: 0;
  bottom: 0;
  left: 0;
  height: var(--tower-max);
  pointer-events: none;
}

.night__layer {
  position: absolute;
  right: 0;
  bottom: 0;
  left: 0;
  display: flex;
  justify-content: center;
  align-items: flex-end;
  gap: calc(var(--window) * 0.5);
}

.night__layer--front {
  --window: var(--window-base);
  --window-gap: calc(var(--window) * 0.7);
  height: var(--tower-max);
}

.night__layer--back {
  --window: calc(var(--window-base) * 0.7);
  --window-gap: calc(var(--window) * 0.8);
  height: calc(var(--tower-max) * 0.78);
  opacity: 0.75;
}

.night__layer--back .night__tower {
  background-color: var(--building-far);
}

.night__layer--back .night__window.is-lit {
  box-shadow: none;
}

.night__tower {
  flex-shrink: 0;
  display: grid;
  grid-template-columns: repeat(var(--cols), var(--window));
  grid-auto-rows: calc(var(--window) * 1.2);
  gap: var(--window-gap);
  padding: var(--window-gap);
  background-color: var(--building);
  border-radius: 0.3rem 0.3rem 0 0;
}

.night__window {
  position: relative;
  background-color: var(--window-off);
  border-radius: 1px;
  transition: background-color 1.6s ease, box-shadow 1.6s ease;
}

.night__window.is-lit {
  background-color: var(--window-lit);
  box-shadow: 0 0 calc(var(--window) * 0.9) var(--window-glow);
}

.night__window.has-curtain::after {
  content: "";
  position: absolute;
  inset: 0;
  opacity: 0;
  background: linear-gradient(90deg, var(--curtain) 0 36%, transparent 36% 64%, var(--curtain) 64% 100%);
  transition: opacity 1.6s ease;
}

.night__window.is-lit.has-curtain::after {
  opacity: 1;
}

.scroll-hint {
  position: absolute;
  bottom: 4rem;
  left: 50%;
  z-index: 3;
  display: grid;
  place-items: center;
  width: 4.5rem;
  height: 4.5rem;
  border: 2px solid var(--color-accent);
  border-radius: 50%;
  background-color: color-mix(in srgb, var(--color-surface) 70%, transparent);
  backdrop-filter: blur(8px);
  box-shadow: 0 0 2rem var(--orb-glow);
  transform: translateX(-50%);
  animation: wiggle 2s ease-in-out infinite;
  transition: background-color var(--transition-fast);
}

.scroll-hint::before {
  content: "";
  width: 1.2rem;
  height: 1.2rem;
  margin-top: -0.45rem;
  border-right: 3px solid var(--color-text);
  border-bottom: 3px solid var(--color-text);
  border-radius: 2px;
  transform: rotate(45deg);
}

.scroll-hint::after {
  content: "";
  position: absolute;
  inset: -2px;
  border: 2px solid var(--color-accent);
  border-radius: 50%;
  animation: ripple 2.4s ease-out infinite;
}

@keyframes wiggle {
  0%, 100% { transform: translate(-50%, 0); }
  50%      { transform: translate(-50%, 0.8rem); }
}

@keyframes ripple {
  0%   { transform: scale(1);   opacity: 0.7; }
  100% { transform: scale(1.7); opacity: 0; }
}

.scroll-hint:hover {
  background-color: var(--color-accent-soft);
}

#principles {
  scroll-margin-top: calc(var(--dock-top) + var(--dock-height));
}

@media (prefers-reduced-motion: reduce) {
  .night-sky__cloud,
  .night-sky__aurora,
  .scroll-hint,
  .scroll-hint::after {
    animation: none;
  }

  .night-sky__stars,
  .night-sky__moon,
  .night-sky__glow,
  .night__layer,
  .hero__inner {
    transition: none;
  }
}