*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --bg: #03040b;
  --ink: #f8fafc;
  --muted: #a8b3c7;
  --panel: rgba(8, 13, 28, 0.72);
  --line: rgba(248, 250, 252, 0.18);
  --cyan: #5eead4;
  --amber: #f8c66a;
  --red: #fb7185;
  --green: #9be56d;
  --violet: #b9a7ff;
}

html {
  height: 100%;
}

body {
  height: 100%;
  overflow: hidden;
  font-family: Inter, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  color: var(--ink);
  background: var(--bg);
}

button {
  font: inherit;
}

.back-bar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 40;
  padding: 0.7rem 1.5rem;
  background: rgba(3, 4, 11, 0.52);
  border-bottom: 1px solid rgba(248, 250, 252, 0.12);
  backdrop-filter: blur(12px);
}

.back-link {
  color: var(--muted);
  font-size: 0.82rem;
  font-weight: 800;
  text-decoration: none;
  transition: color 0.2s ease;
}

.back-link:hover {
  color: var(--ink);
}

.scale-panel {
  position: fixed;
  top: 4.2rem;
  left: 1.25rem;
  z-index: 35;
  width: min(17rem, calc(100vw - 2rem));
  padding: 0.9rem;
  background: var(--panel);
  border: 1px solid rgba(248, 250, 252, 0.16);
  border-radius: 0.5rem;
  box-shadow: 0 24px 70px rgba(0, 0, 0, 0.34);
  backdrop-filter: blur(16px);
}

.scale-panel__label {
  color: var(--muted);
  font-size: 0.68rem;
  font-weight: 900;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.scale-panel__value {
  margin-top: 0.25rem;
  color: var(--cyan);
  font-size: clamp(1.4rem, 7vw, 2.35rem);
  font-weight: 950;
  line-height: 1;
  font-variant-numeric: tabular-nums;
}

.scale-panel__object {
  min-height: 1.3rem;
  margin-top: 0.45rem;
  color: var(--ink);
  font-size: 0.86rem;
  font-weight: 850;
}

.scale-progress {
  height: 6px;
  margin-top: 0.8rem;
  overflow: hidden;
  background: rgba(248, 250, 252, 0.12);
  border-radius: 999px;
}

.scale-progress span {
  display: block;
  width: 0;
  height: 100%;
  background: linear-gradient(90deg, var(--cyan), var(--amber), var(--red), var(--violet));
  border-radius: inherit;
}

.control-pad {
  position: fixed;
  right: 1.25rem;
  bottom: 1.25rem;
  z-index: 35;
  display: flex;
  gap: 0.55rem;
}

.control-btn {
  width: 3rem;
  height: 3rem;
  color: var(--ink);
  font-size: 2rem;
  font-weight: 900;
  line-height: 1;
  cursor: pointer;
  background: rgba(8, 13, 28, 0.74);
  border: 1px solid rgba(248, 250, 252, 0.2);
  border-radius: 0.5rem;
  backdrop-filter: blur(14px);
  transition: transform 0.18s ease, border-color 0.18s ease, background 0.18s ease;
}

.control-btn:hover {
  transform: translateY(-2px);
  background: rgba(25, 36, 67, 0.86);
  border-color: rgba(94, 234, 212, 0.6);
}

.space-scroll {
  position: fixed;
  inset: 0;
  overflow: auto hidden;
  scroll-behavior: smooth;
  scrollbar-width: thin;
  scrollbar-color: rgba(94, 234, 212, 0.45) rgba(248, 250, 252, 0.08);
  cursor: grab;
}

.space-scroll:active {
  cursor: grabbing;
}

.space-scroll::-webkit-scrollbar {
  height: 10px;
}

.space-scroll::-webkit-scrollbar-track {
  background: rgba(248, 250, 252, 0.08);
}

.space-scroll::-webkit-scrollbar-thumb {
  background: rgba(94, 234, 212, 0.45);
  border-radius: 999px;
}

.scroll-content {
  display: flex;
  width: max-content;
  height: 100%;
}

.intro-panel {
  position: relative;
  flex: 0 0 100vw;
  min-width: 100vw;
  height: 100vh;
  display: grid;
  place-items: center;
  align-content: center;
  gap: 1rem;
  overflow: hidden;
  padding: 7rem 1.5rem 5rem;
  text-align: center;
  background:
    radial-gradient(circle at 50% 54%, rgba(94, 234, 212, 0.28), transparent 19rem),
    radial-gradient(circle at 72% 28%, rgba(185, 167, 255, 0.26), transparent 17rem),
    linear-gradient(180deg, #050816 0%, #090b24 48%, #03040b 100%);
}

.intro-panel::after,
.scale-stage::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image:
    radial-gradient(circle, rgba(255, 255, 255, 0.85) 0 1px, transparent 1.2px),
    radial-gradient(circle, rgba(255, 255, 255, 0.45) 0 1px, transparent 1.2px);
  background-position: 0 0, 72px 118px;
  background-size: 180px 180px, 260px 260px;
  opacity: 0.34;
}

.intro-stars {
  position: absolute;
  inset: 0;
  pointer-events: none;
  background:
    linear-gradient(90deg, transparent, rgba(94, 234, 212, 0.16), transparent),
    linear-gradient(180deg, transparent, rgba(255, 255, 255, 0.05));
}

.eyebrow {
  position: relative;
  z-index: 1;
  color: var(--cyan);
  font-size: 0.78rem;
  font-weight: 950;
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

.intro-panel h1 {
  position: relative;
  z-index: 1;
  max-width: 920px;
  color: var(--ink);
  font-size: clamp(3rem, 12vw, 8rem);
  font-weight: 950;
  letter-spacing: 0;
  line-height: 0.92;
}

.intro-panel p {
  position: relative;
  z-index: 1;
  max-width: 700px;
  color: var(--muted);
  font-size: clamp(1rem, 2.4vw, 1.2rem);
  font-weight: 650;
  line-height: 1.58;
}

.start-cue {
  position: relative;
  z-index: 1;
  margin-top: 1rem;
  color: var(--amber);
  font-size: 0.8rem;
  font-weight: 900;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.scale-stage {
  position: relative;
  flex: 0 0 auto;
  height: 100vh;
  overflow: hidden;
  background:
    linear-gradient(90deg, #03040b 0%, #070b1f 18%, #08162f 36%, #151333 56%, #1b1027 74%, #05030a 100%);
}

.stage-glow {
  position: absolute;
  inset: 0;
  pointer-events: none;
  background:
    radial-gradient(circle at 14% 46%, rgba(94, 234, 212, 0.12), transparent 30rem),
    radial-gradient(circle at 42% 38%, rgba(248, 198, 106, 0.12), transparent 34rem),
    radial-gradient(circle at 74% 48%, rgba(251, 113, 133, 0.13), transparent 38rem),
    radial-gradient(circle at 92% 42%, rgba(185, 167, 255, 0.17), transparent 35rem);
}

.scale-axis {
  position: absolute;
  left: 0;
  right: 0;
  top: 50%;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--line), transparent);
}

.axis-tick {
  position: absolute;
  top: -0.45rem;
  width: 1px;
  height: 0.9rem;
  background: rgba(248, 250, 252, 0.28);
}

.axis-tick span {
  position: absolute;
  top: 1rem;
  left: 50%;
  color: rgba(248, 250, 252, 0.62);
  font-size: 0.72rem;
  font-weight: 800;
  white-space: nowrap;
  transform: translateX(-50%);
}

.object-layer {
  position: absolute;
  inset: 0;
}

.space-item {
  position: absolute;
  top: var(--lane-top);
  width: clamp(13rem, 24vw, 18rem);
  opacity: 0.34;
  transform: translate(-50%, -50%) scale(0.92);
  transition: opacity 0.24s ease, transform 0.24s ease, filter 0.24s ease;
  filter: saturate(0.8);
}

.space-item.is-visible {
  opacity: 0.78;
  transform: translate(-50%, -50%) scale(1);
}

.space-item.is-active {
  z-index: 4;
  opacity: 1;
  transform: translate(-50%, -50%) scale(1.08);
  filter: saturate(1.1) drop-shadow(0 0 28px rgba(94, 234, 212, 0.18));
}

.object-art {
  width: var(--art-size);
  max-width: 13rem;
  min-width: 3.6rem;
  margin: 0 auto 0.75rem;
  aspect-ratio: 1;
  display: grid;
  place-items: center;
}

.object-art svg {
  width: 100%;
  height: 100%;
  overflow: visible;
}

.object-card {
  padding: 0.85rem 0.95rem;
  background: rgba(8, 13, 28, 0.7);
  border: 1px solid rgba(248, 250, 252, 0.14);
  border-radius: 0.5rem;
  box-shadow: 0 22px 60px rgba(0, 0, 0, 0.28);
  backdrop-filter: blur(12px);
}

.object-size {
  color: var(--amber);
  font-size: 0.75rem;
  font-weight: 950;
  letter-spacing: 0.04em;
  font-variant-numeric: tabular-nums;
}

.object-card h2 {
  margin-top: 0.2rem;
  color: var(--ink);
  font-size: clamp(1.1rem, 3vw, 1.55rem);
  line-height: 1.12;
  letter-spacing: 0;
}

.object-card p {
  margin-top: 0.45rem;
  color: var(--muted);
  font-size: 0.84rem;
  line-height: 1.5;
}

@media (max-width: 760px) {
  .scale-panel {
    top: auto;
    left: 0.75rem;
    bottom: 0.75rem;
    width: calc(100vw - 1.5rem);
  }

  .control-pad {
    right: 0.75rem;
    top: 4.1rem;
    bottom: auto;
  }

  .control-btn {
    width: 2.6rem;
    height: 2.6rem;
  }

  .space-item {
    top: min(var(--lane-top), 54%);
    width: 13rem;
  }

  .object-card p {
    font-size: 0.78rem;
  }

  .start-cue {
    max-width: 18rem;
    line-height: 1.45;
  }
}

@media (prefers-reduced-motion: reduce) {
  .space-scroll {
    scroll-behavior: auto;
  }

  .space-item,
  .back-link,
  .control-btn {
    transition: none;
  }
}