:root {
  --bg1: #0f1e2a;
  --bg2: #162838;
  --card: #f6f8fb;
  --ink: #1b2430;
  --accent: #1976d2;
  --accent2: #f4a300;
  --danger: #c83333;
  --ok: #1a9b47;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  color: var(--ink);
  background: radial-gradient(circle at 20% 10%, #1e3a52, var(--bg1) 40%, #09141e 100%);
}

.app {
  max-width: 1200px;
  margin: 0 auto;
  padding: 1.2rem;
  display: grid;
  gap: 1rem;
}

header {
  color: #eaf4ff;
}

header h1 {
  margin: 0 0 0.35rem;
  font-size: 1.5rem;
}

header p {
  margin: 0;
  opacity: 0.9;
}

.controls {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 0.9rem;
}

.card {
  background: var(--card);
  border-radius: 14px;
  padding: 0.9rem;
  box-shadow: 0 10px 24px rgba(0, 0, 0, 0.25);
}

.card h2 {
  margin: 0 0 0.75rem;
  font-size: 1.05rem;
}

.titleWithHelp {
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

.row {
  display: grid;
  grid-template-columns: 1fr auto auto;
  align-items: center;
  gap: 0.45rem;
  margin-bottom: 0.55rem;
}

.row input[type="number"],
.row select {
  width: 100%;
  min-width: 90px;
  border: 1px solid #bcc5ce;
  border-radius: 8px;
  padding: 0.4rem 0.45rem;
  font: inherit;
}

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

.sliderRow input[type="range"] {
  width: 100%;
}

button {
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: 10px;
  padding: 0.55rem 0.85rem;
  font: inherit;
  cursor: pointer;
}

button:hover {
  filter: brightness(1.06);
}

button:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  filter: none;
}

.labelWithHelp {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
}

.helpBtn {
  width: 1.2rem;
  height: 1.2rem;
  min-width: 1.2rem;
  padding: 0;
  border-radius: 999px;
  font-size: 0.78rem;
  line-height: 1;
  font-weight: 700;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: #3c4d61;
  color: #eef5ff;
}

.helpTooltip {
  position: fixed;
  z-index: 3000;
  max-width: 290px;
  padding: 0.5rem 0.6rem;
  border-radius: 8px;
  background: #152b3f;
  color: #e9f4ff;
  border: 1px solid #7fa6c8;
  box-shadow: 0 12px 22px rgba(0, 0, 0, 0.35);
  font-size: 0.86rem;
  line-height: 1.35;
  pointer-events: none;
}

.preview {
  padding-bottom: 0.6rem;
}

.stats {
  display: grid;
  gap: 0.3rem;
  margin-bottom: 0.6rem;
}

.stats .heavy {
  font-weight: 700;
}

.stats .heavy.left {
  color: var(--accent2);
}

.stats .heavy.right {
  color: var(--accent2);
}

.stats .heavy.balanced {
  color: #2e5f93;
}

.stats .heavy.danger {
  color: var(--danger);
}

.sceneWrap {
  width: 100%;
  border-radius: 10px;
  overflow: hidden;
  border: 1px solid #9badc0;
}

#scene {
  display: block;
  width: 100%;
  height: auto;
}

.bg {
  fill: #0c1b2a;
}

.shaft {
  stroke: #9ca8b3;
  stroke-width: 12;
  stroke-linecap: round;
}

.axis {
  fill: #ced6de;
  stroke: #7b8691;
  stroke-width: 3;
}

.axisCore {
  fill: #33414f;
}

.otaCircle {
  fill: #2f5f8f;
  stroke: #9bc9f2;
  stroke-width: 3;
}

.otaText {
  fill: #eff7ff;
  text-anchor: middle;
  dominant-baseline: middle;
  font-weight: 700;
  letter-spacing: 0.08em;
  pointer-events: none;
}

.weight {
  fill: #d3a053;
  stroke: #7c5a2f;
  stroke-width: 2;
  cursor: grab;
}

.weight.dragging {
  fill: #f2c37a;
  cursor: grabbing;
}

.distLabel {
  fill: #eef4fb;
  font-size: 13px;
  text-anchor: middle;
  font-weight: 600;
  pointer-events: none;
  paint-order: stroke;
  stroke: #0b1a28;
  stroke-width: 3px;
  stroke-linejoin: round;
}

.otaInfoLabel {
  font-size: 12px;
}

.hint {
  margin: 0.45rem 0 0;
  color: #253747;
  font-size: 0.95rem;
}

@media (max-width: 700px) {
  .row {
    grid-template-columns: 1fr;
  }
}