:root {
  color-scheme: light;
  --bg: #eef3f7;
  --panel: rgba(255, 255, 255, 0.82);
  --panel-border: rgba(23, 45, 74, 0.12);
  --text: #102033;
  --muted: #58708c;
  --accent: #ff8f3f;
  --accent-strong: #ea5f23;
  --scale-width: 92px;
  --scale-offset: 20px;
  --ground-height: 72px;
  --lane-padding: 18px;
  --sphere-size: 44px;
  --stage-gradient: linear-gradient(180deg, #77c3ff 0%, #d9eefc 62%, #f6e2bd 100%);
  --stage-grid: rgba(255, 255, 255, 0.18);
  --badge-bg: rgba(255, 255, 255, 0.72);
  --badge-border: rgba(255, 255, 255, 0.45);
  --badge-text: #102033;
  --lane-line: rgba(255, 255, 255, 0.5);
  --lane-glow: rgba(255, 255, 255, 0.08);
  --ground-main: linear-gradient(180deg, rgba(255, 239, 214, 0.8), rgba(174, 115, 72, 0.92));
  --ground-overlay: linear-gradient(90deg, rgba(0, 0, 0, 0.1), transparent);
  --glow-a: rgba(255, 247, 204, 0.5);
  --glow-b: rgba(255, 173, 84, 0.28);
  --cloud-opacity: 0.7;
  --cloud-color: rgba(255, 255, 255, 0.65);
  --haze-color: rgba(255, 244, 214, 0.18);
  --ground-label: rgba(255, 255, 255, 0.95);
  --scale-line: rgba(16, 32, 51, 0.2);
  --scale-text: rgba(16, 32, 51, 0.68);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: "Space Grotesk", sans-serif;
  background:
    radial-gradient(circle at top, rgba(255, 255, 255, 0.96), transparent 32%),
    linear-gradient(135deg, #c2d2de 0%, #edf3f7 42%, #dbe4ec 100%);
  color: var(--text);
}

.app-shell {
  display: grid;
  grid-template-columns: minmax(0, 1.6fr) minmax(320px, 1fr);
  min-height: 100vh;
}

.simulation-panel,
.control-panel {
  padding: 28px;
}

.simulation-panel {
  display: flex;
  flex-direction: column;
  gap: 18px;
  min-height: 100vh;
}

.simulation-topbar {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 16px;
}

.eyebrow {
  margin: 0 0 6px;
  text-transform: uppercase;
  letter-spacing: 0.14em;
  font-size: 0.72rem;
  color: var(--muted);
}

h1,
h2,
h3,
p {
  margin: 0;
}

h1,
h2 {
  font-size: clamp(1.8rem, 2vw, 2.6rem);
}

h3 {
  font-size: 1rem;
  margin-bottom: 16px;
}

.environment-chip,
.formula-card,
.panel-section,
.result-card {
  backdrop-filter: blur(12px);
  background: var(--panel);
  border: 1px solid var(--panel-border);
  box-shadow: 0 20px 45px rgba(17, 33, 57, 0.08);
}

.environment-chip {
  padding: 10px 14px;
  border-radius: 999px;
  font-size: 0.92rem;
  font-weight: 700;
}

.simulation-stage {
  position: relative;
  flex: 0 0 auto;
  height: min(78vh, 720px);
  min-height: 620px;
  overflow: hidden;
  border-radius: 34px;
  background: var(--stage-gradient);
  border: 1px solid rgba(255, 255, 255, 0.4);
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.55),
    inset 0 -40px 80px rgba(11, 26, 46, 0.08),
    0 30px 60px rgba(10, 24, 42, 0.18);
}

.simulation-stage::before {
  content: "";
  position: absolute;
  inset: 0;
  background:
    linear-gradient(90deg, transparent 0 11.7%, var(--stage-grid) 11.8%, transparent 11.9%),
    linear-gradient(180deg, rgba(255, 255, 255, 0.08), transparent 30%, transparent 70%, rgba(0, 0, 0, 0.08));
  mix-blend-mode: soft-light;
  pointer-events: none;
}

.simulation-stage::after {
  content: "";
  position: absolute;
  inset: 14px;
  border-radius: 28px;
  border: 1px solid rgba(255, 255, 255, 0.18);
  pointer-events: none;
}

.height-badge {
  position: absolute;
  top: 18px;
  right: 18px;
  z-index: 4;
  min-width: 152px;
  padding: 14px 16px;
  border-radius: 20px;
  backdrop-filter: blur(12px);
  background: var(--badge-bg);
  border: 1px solid var(--badge-border);
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.36),
    0 16px 30px rgba(10, 24, 42, 0.14);
  text-align: right;
}

.height-badge-label {
  display: block;
  margin-bottom: 4px;
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: color-mix(in srgb, var(--badge-text) 58%, transparent);
}

.height-badge strong {
  font-family: "JetBrains Mono", monospace;
  font-size: 1.18rem;
  color: var(--badge-text);
}

.stars,
.atmosphere,
.ground-glow,
.orbital-glow,
.cloud-bank,
.haze {
  position: absolute;
  inset: 0;
  pointer-events: none;
}

.orbital-glow {
  border-radius: 50%;
  filter: blur(2px);
}

.orbital-glow-a {
  inset: auto auto 72% 68%;
  width: 220px;
  height: 220px;
  background: radial-gradient(circle, var(--glow-a) 0%, transparent 70%);
  opacity: 0.9;
}

.orbital-glow-b {
  inset: 6% auto auto -5%;
  width: 280px;
  height: 280px;
  background: radial-gradient(circle, var(--glow-b) 0%, transparent 72%);
  opacity: 0.9;
}

.stars {
  opacity: 0;
  background-image:
    radial-gradient(circle at 12% 18%, rgba(255, 255, 255, 0.8) 0 1px, transparent 2px),
    radial-gradient(circle at 72% 14%, rgba(255, 255, 255, 0.75) 0 1.5px, transparent 2.5px),
    radial-gradient(circle at 84% 42%, rgba(255, 255, 255, 0.7) 0 1px, transparent 2px),
    radial-gradient(circle at 23% 48%, rgba(255, 255, 255, 0.7) 0 1.4px, transparent 2.4px),
    radial-gradient(circle at 64% 63%, rgba(255, 255, 255, 0.8) 0 1px, transparent 2px);
  transition: opacity 300ms ease;
}

.atmosphere {
  background:
    radial-gradient(circle at 50% 8%, rgba(255, 255, 255, 0.45), transparent 30%),
    radial-gradient(circle at 50% 115%, rgba(255, 214, 138, 0.22), transparent 34%),
    linear-gradient(180deg, rgba(255, 255, 255, 0.12), transparent 28%);
}

.haze {
  background:
    radial-gradient(circle at 50% 92%, var(--haze-color), transparent 48%),
    linear-gradient(180deg, transparent 55%, rgba(255, 255, 255, 0.06) 100%);
}

.cloud-bank {
  opacity: var(--cloud-opacity);
  filter: blur(0.5px);
}

.cloud-bank-a {
  background:
    radial-gradient(circle at 12% 38%, var(--cloud-color) 0 8%, transparent 9%),
    radial-gradient(circle at 20% 38%, var(--cloud-color) 0 10%, transparent 11%),
    radial-gradient(circle at 30% 39%, var(--cloud-color) 0 8%, transparent 9%),
    radial-gradient(circle at 80% 24%, var(--cloud-color) 0 7%, transparent 8%),
    radial-gradient(circle at 87% 24%, var(--cloud-color) 0 9%, transparent 10%),
    radial-gradient(circle at 94% 25%, var(--cloud-color) 0 7%, transparent 8%);
}

.cloud-bank-b {
  background:
    radial-gradient(circle at 58% 56%, color-mix(in srgb, var(--cloud-color) 84%, transparent) 0 8%, transparent 9%),
    radial-gradient(circle at 66% 56%, color-mix(in srgb, var(--cloud-color) 84%, transparent) 0 10%, transparent 11%),
    radial-gradient(circle at 74% 56%, color-mix(in srgb, var(--cloud-color) 84%, transparent) 0 8%, transparent 9%),
    radial-gradient(circle at 32% 72%, color-mix(in srgb, var(--cloud-color) 66%, transparent) 0 7%, transparent 8%),
    radial-gradient(circle at 38% 72%, color-mix(in srgb, var(--cloud-color) 66%, transparent) 0 9%, transparent 10%),
    radial-gradient(circle at 45% 72%, color-mix(in srgb, var(--cloud-color) 66%, transparent) 0 7%, transparent 8%);
}

.ground-glow {
  top: auto;
  height: 220px;
  background:
    radial-gradient(circle at 50% 100%, rgba(254, 177, 97, 0.34), transparent 58%),
    linear-gradient(180deg, transparent, rgba(255, 227, 170, 0.06));
}

.meter-scale {
  position: absolute;
  left: var(--scale-offset);
  top: 26px;
  bottom: calc(var(--ground-height) + 18px);
  width: var(--scale-width);
  padding: 0 12px 0 12px;
  border-right: 1px solid rgba(255, 255, 255, 0.12);
}

.scale-tick {
  position: absolute;
  left: 30px;
  right: 10px;
  height: 1px;
  color: var(--scale-text);
  background: var(--scale-line);
}

.scale-tick::before {
  content: attr(data-label);
  position: absolute;
  left: 0;
  transform: translate(-100%, -50%);
  top: 50%;
  font-size: 0.75rem;
  font-weight: 700;
  color: currentColor;
}

.fall-lane {
  position: absolute;
  left: calc(var(--scale-offset) + var(--scale-width) + var(--lane-padding));
  right: 22px;
  top: 26px;
  bottom: calc(var(--ground-height) + 18px);
}

.fall-lane::before {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  bottom: 0;
  background:
    linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.07) 12%, transparent 24%),
    repeating-linear-gradient(180deg, transparent 0 18px, rgba(255, 255, 255, 0.035) 18px 19px);
  border-radius: 24px;
}

.fall-lane::after {
  content: "";
  position: absolute;
  left: 50%;
  top: 0;
  bottom: 0;
  width: 4px;
  transform: translateX(-50%);
  border-radius: 999px;
  background:
    linear-gradient(180deg, var(--lane-line), rgba(255, 255, 255, 0.08)),
    var(--lane-glow);
  box-shadow:
    0 0 0 1px rgba(255, 255, 255, 0.18),
    0 0 26px rgba(255, 255, 255, 0.08);
}

.sphere,
.drop-shadow,
.impact-burst {
  position: absolute;
}

.sphere {
  width: var(--sphere-size);
  height: var(--sphere-size);
  border-radius: 50%;
  z-index: 3;
  cursor: grab;
  touch-action: none;
  background:
    radial-gradient(circle at 28% 24%, rgba(255, 255, 255, 1) 0 10%, rgba(255, 255, 255, 0.85) 11%, transparent 22%),
    radial-gradient(circle at 34% 30%, #ffffff 0%, #dce5ef 18%, #92a4b7 44%, #556779 72%, #243240 100%);
  box-shadow:
    inset -11px -14px 18px rgba(0, 0, 0, 0.3),
    inset 9px 8px 14px rgba(255, 255, 255, 0.42),
    0 12px 24px rgba(18, 33, 57, 0.22),
    0 0 0 1px rgba(255, 255, 255, 0.28);
  transition: transform 120ms ease;
}

.sphere.is-draggable:focus-visible {
  outline: 3px solid rgba(255, 255, 255, 0.9);
  outline-offset: 4px;
}

.sphere.is-dragging {
  cursor: grabbing;
  transition: none;
}

.drop-shadow {
  width: 56px;
  height: 16px;
  bottom: -4px;
  z-index: 1;
  pointer-events: none;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(26, 19, 16, 0.28) 0%, rgba(26, 19, 16, 0.04) 58%, rgba(26, 19, 16, 0) 74%);
}

.impact-burst {
  width: 110px;
  height: 32px;
  bottom: -2px;
  z-index: 2;
  pointer-events: none;
  opacity: 0;
  transform: scale(0.6);
  transform-origin: center bottom;
  background:
    radial-gradient(circle at 20% 50%, rgba(255, 214, 149, 0.8) 0 7px, transparent 8px),
    radial-gradient(circle at 50% 22%, rgba(255, 238, 204, 0.75) 0 8px, transparent 9px),
    radial-gradient(circle at 76% 54%, rgba(255, 214, 149, 0.8) 0 7px, transparent 8px),
    radial-gradient(circle at 50% 78%, rgba(210, 156, 91, 0.7) 0 11px, transparent 12px);
}

.impact-burst.is-active {
  animation: burst 420ms ease-out forwards;
}

@keyframes burst {
  0% {
    opacity: 0;
    transform: scale(0.6);
  }
  25% {
    opacity: 0.95;
  }
  100% {
    opacity: 0;
    transform: scale(1.2);
  }
}

.ground {
  position: absolute;
  left: 18px;
  right: 18px;
  bottom: 18px;
  height: var(--ground-height);
  padding: 18px 22px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-radius: 26px;
  background:
    radial-gradient(circle at 16% 28%, rgba(255, 255, 255, 0.14) 0 7%, transparent 8%),
    radial-gradient(circle at 44% 74%, rgba(0, 0, 0, 0.08) 0 6%, transparent 7%),
    radial-gradient(circle at 72% 42%, rgba(255, 255, 255, 0.11) 0 8%, transparent 9%),
    var(--ground-main),
    var(--ground-overlay);
  color: var(--ground-label);
  font-weight: 700;
  letter-spacing: 0.03em;
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.18),
    0 12px 24px rgba(34, 21, 15, 0.16);
}

.control-panel {
  display: flex;
  flex-direction: column;
  gap: 18px;
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.74), rgba(255, 255, 255, 0.4));
  border-left: 1px solid rgba(255, 255, 255, 0.6);
}

.formula-card {
  padding: 18px 20px;
  border-radius: 24px;
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.84), rgba(249, 250, 252, 0.74));
}

.formula-label {
  display: block;
  margin-bottom: 6px;
  font-size: 0.85rem;
  color: var(--muted);
}

.formula-derivation {
  display: grid;
  gap: 6px;
}

.formula-derivation p,
.formula-derivation strong {
  font-family: "JetBrains Mono", monospace;
}

.formula-derivation p {
  font-size: 0.95rem;
  line-height: 1.45;
}

.formula-card strong,
.math-block,
.timer-display {
  font-family: "JetBrains Mono", monospace;
}

.panel-section {
  border-radius: 24px;
  padding: 20px;
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.88), rgba(252, 252, 253, 0.76));
}

.field {
  display: grid;
  gap: 12px;
}

.field + .field,
.field-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 14px;
}

input[type="range"],
select {
  width: 100%;
}

input[type="range"] {
  appearance: none;
  height: 10px;
  border-radius: 999px;
  background: linear-gradient(90deg, #ffbd78 0%, #ff8745 100%);
  outline: none;
}

input[type="range"]::-webkit-slider-thumb {
  appearance: none;
  width: 24px;
  height: 24px;
  border-radius: 50%;
  background: #fff;
  border: 3px solid var(--accent-strong);
  box-shadow: 0 6px 16px rgba(234, 95, 35, 0.32);
  cursor: pointer;
}

input[type="range"]::-moz-range-thumb {
  width: 24px;
  height: 24px;
  border-radius: 50%;
  background: #fff;
  border: 3px solid var(--accent-strong);
  box-shadow: 0 6px 16px rgba(234, 95, 35, 0.32);
  cursor: pointer;
}

select {
  border: 1px solid rgba(16, 32, 51, 0.14);
  border-radius: 16px;
  padding: 14px 16px;
  font: inherit;
  color: var(--text);
  background: rgba(255, 255, 255, 0.95);
}

select:disabled,
input:disabled {
  cursor: not-allowed;
  opacity: 0.55;
}

.environment-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
}

.environment-button {
  width: 100%;
  border: 1px solid rgba(16, 32, 51, 0.12);
  border-radius: 18px;
  padding: 14px 14px 13px;
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.96), rgba(245, 247, 250, 0.88));
  color: var(--text);
  text-align: left;
  font: inherit;
  cursor: pointer;
  transition: transform 120ms ease, box-shadow 120ms ease, border-color 120ms ease, background 120ms ease;
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.7);
}

.environment-button:hover:enabled {
  transform: translateY(-1px);
  box-shadow: 0 12px 22px rgba(17, 33, 57, 0.08);
}

.environment-button span,
.environment-button strong {
  display: block;
}

.environment-button span {
  font-size: 0.95rem;
  font-weight: 700;
}

.environment-button strong {
  margin-top: 4px;
  font-size: 0.83rem;
  color: var(--muted);
}

.environment-button.is-active {
  border-color: rgba(234, 95, 35, 0.35);
  background:
    linear-gradient(135deg, rgba(255, 165, 98, 0.22), rgba(255, 227, 177, 0.24));
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.6),
    0 14px 24px rgba(234, 95, 35, 0.12);
}

.environment-button:disabled {
  cursor: not-allowed;
  opacity: 0.55;
}

.drag-hint {
  margin-top: 18px;
  padding: 15px 16px;
  border-radius: 18px;
  background:
    linear-gradient(135deg, rgba(255, 152, 80, 0.15), rgba(255, 207, 136, 0.12));
  border: 1px solid rgba(255, 152, 80, 0.16);
  color: var(--text);
  font-size: 0.94rem;
  line-height: 1.45;
}

.timer-display {
  font-size: clamp(2rem, 4vw, 3.25rem);
  letter-spacing: 0.04em;
  padding: 16px 18px;
  border-radius: 22px;
  background:
    linear-gradient(180deg, #09131f 0%, #101d2e 100%);
  color: #7dff9f;
  box-shadow:
    inset 0 0 0 1px rgba(125, 255, 159, 0.15),
    inset 0 -12px 24px rgba(0, 0, 0, 0.25);
}

.result-section {
  transition: opacity 180ms ease, transform 180ms ease;
}

.result-section.is-hidden {
  display: none;
}

.result-card {
  padding: 18px;
  border-radius: 20px;
}

.result-card p + .math-block {
  margin-top: 16px;
}

.math-block {
  display: grid;
  gap: 8px;
  padding: 16px;
  border-radius: 16px;
  background:
    linear-gradient(180deg, rgba(16, 32, 51, 0.05), rgba(16, 32, 51, 0.08));
  font-size: 0.98rem;
}

@media (max-width: 980px) {
  .app-shell {
    grid-template-columns: 1fr;
  }

  .simulation-stage {
    height: min(62vh, 560px);
    min-height: 500px;
  }

  .control-panel {
    border-left: 0;
    border-top: 1px solid rgba(255, 255, 255, 0.6);
  }
}

@media (max-width: 640px) {
  .simulation-panel,
  .control-panel {
    padding: 18px;
  }

  .simulation-stage {
    height: min(56vh, 480px);
    min-height: 420px;
  }

  .simulation-topbar,
  .field-top {
    grid-template-columns: 1fr;
    display: grid;
  }

  .environment-chip {
    width: fit-content;
  }

  .environment-grid {
    grid-template-columns: 1fr;
  }
}