:root {
  --bg: #eef1f5;
  --bg-deep: #d6dce4;
  --panel: rgba(255, 255, 255, 0.86);
  --ink: #1c222a;
  --muted: #5b6673;
  --line: #cbd2db;
  --button: #ffffff;
  --button-hover: #f0f3f7;
  --accent: #2f5fd0;
  --accent-ink: #ffffff;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #262c34;
    --bg-deep: #14171c;
    --panel: rgba(30, 35, 42, 0.88);
    --ink: #e7ebf0;
    --muted: #9ba6b3;
    --line: #363e49;
    --button: #2a313a;
    --button-hover: #333b46;
    --accent: #5b86f0;
  }
}

* { box-sizing: border-box; }

html, body { height: 100%; margin: 0; }

body {
  display: flex;
  flex-direction: column;
  overflow: hidden;
  font: 14px/1.4 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  color: var(--ink);
  background: var(--bg);
}

button {
  font: inherit;
  color: inherit;
  background: var(--button);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 6px 12px;
  cursor: pointer;
}
button:hover { background: var(--button-hover); }
button:disabled { opacity: 0.45; cursor: default; background: var(--button); }
button[aria-pressed="true"] { background: var(--accent); border-color: var(--accent); color: var(--accent-ink); }
button:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

.bar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px 16px;
  padding: 10px 16px;
  background: var(--panel);
  border-bottom: 1px solid var(--line);
}
.brand { display: flex; align-items: baseline; gap: 8px; margin-right: auto; }
h1 { margin: 0; font-size: 18px; letter-spacing: -0.01em; }
.tag { color: var(--muted); font-size: 13px; }
.tools, .actions { display: flex; flex-wrap: wrap; gap: 6px; }

main { flex: 1; display: flex; min-height: 0; }

.palette {
  width: 292px;
  flex-shrink: 0;
  padding: 12px;
  overflow-y: auto;
  background: var(--panel);
  border-right: 1px solid var(--line);
}
.chips { display: grid; grid-template-columns: 1fr 1fr; gap: 6px; }
.chip {
  display: grid;
  grid-template-columns: 30px 1fr;
  column-gap: 8px;
  align-items: center;
  padding: 6px 8px;
  text-align: left;
}
.ball {
  position: relative;
  grid-row: span 2;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background:
    radial-gradient(circle at 35% 30%, rgba(255, 255, 255, 0.7), rgba(255, 255, 255, 0) 45%),
    var(--c);
  box-shadow: inset 0 -2px 4px rgba(0, 0, 0, 0.25), 0 0 0 1px rgba(0, 0, 0, 0.15);
}
.ball::after {
  content: attr(data-n);
  position: absolute;
  right: -5px;
  bottom: -4px;
  min-width: 15px;
  height: 15px;
  padding: 0 3px;
  border-radius: 8px;
  font-size: 10px;
  font-weight: 600;
  line-height: 15px;
  text-align: center;
  color: var(--bg);
  background: var(--ink);
}
.chip { touch-action: pan-y; }
.ball.dragging {
  position: fixed;
  z-index: 10;
  width: 30px;
  height: 30px;
  pointer-events: none;
  transform: translate(-130%, -130%);
  opacity: 0.9;
}
.sym { font-size: 15px; font-weight: 650; line-height: 1.1; white-space: nowrap; }
.el-name { font-size: 12px; font-weight: 500; }
.geo { font-size: 11px; color: var(--muted); line-height: 1.2; }
.chip[aria-pressed="true"] .geo { color: inherit; opacity: 0.85; }

.stage {
  position: relative;
  flex: 1;
  min-width: 0;
  background: radial-gradient(ellipse at 50% 40%, var(--bg), var(--bg-deep));
}
#scene { position: absolute; inset: 0; width: 100%; height: 100%; display: block; touch-action: none; }

.hint, .readout, .help, .toast { position: absolute; margin: 0; pointer-events: none; }
.hint {
  top: 12px;
  left: 50%;
  transform: translateX(-50%);
  width: max-content;
  max-width: calc(100% - 32px);
  padding: 6px 14px;
  border-radius: 999px;
  text-align: center;
  font-size: 13px;
  color: var(--muted);
  background: var(--panel);
  border: 1px solid var(--line);
}
.toast {
  top: 52px;
  left: 50%;
  transform: translate(-50%, -6px);
  max-width: calc(100% - 32px);
  padding: 8px 14px;
  border-radius: 8px;
  color: var(--bg);
  background: var(--ink);
  opacity: 0;
  transition: opacity 0.2s, transform 0.2s;
}
.toast.show { opacity: 1; transform: translate(-50%, 0); }
.readout {
  left: 16px;
  bottom: 16px;
  padding: 10px 14px;
  border-radius: 12px;
  background: var(--panel);
  border: 1px solid var(--line);
}
.readout { max-width: min(440px, calc(100% - 32px)); overflow-wrap: anywhere; }
.readout a { pointer-events: auto; color: var(--accent); }
.name { font-size: 18px; font-weight: 650; }
.name.status { font-size: 13px; font-weight: 500; color: var(--muted); }
.subname { font-size: 12px; color: var(--muted); margin-bottom: 4px; }
.formula { font-size: 22px; font-weight: 650; }
.details { font-size: 12px; color: var(--muted); }
.help { right: 16px; bottom: 16px; max-width: 300px; text-align: right; font-size: 12px; color: var(--muted); }

@media (max-width: 720px) {
  .tag, .help { display: none; }
  .bar { padding: 8px 16px; }
  main { flex-direction: column-reverse; }
  .palette {
    width: auto;
    padding: 8px 16px;
    overflow-x: auto;
    overflow-y: hidden;
    border-right: 0;
    border-top: 1px solid var(--line);
  }
  .chips { grid-template-columns: none; grid-auto-flow: column; grid-auto-columns: max-content; }
  .chip { touch-action: pan-x; }
  .readout { left: 16px; bottom: 12px; padding: 8px 12px; }
  .formula { font-size: 18px; }
}