:root {
  --bg: #0b0e14;
  --panel: #121722;
  --panel2: #0e131c;
  --border: #232c3d;
  --text: #dde5f2;
  --muted: #8b96a8;
  --accent: #22d3ee;
  --accent2: #e879f9;
  --danger: #f87171;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background:
    radial-gradient(1100px 600px at 75% -10%, rgba(34, 211, 238, .07), transparent 60%),
    radial-gradient(900px 500px at 5% 110%, rgba(232, 121, 249, .06), transparent 60%),
    var(--bg);
  color: var(--text);
  font-family: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, -apple-system, sans-serif;
  -webkit-font-smoothing: antialiased;
}

.wrap { max-width: 1180px; margin: 0 auto; padding: 22px 16px 48px; }

header { text-align: center; margin: 6px 0 18px; }
h1 {
  font-size: 1.7rem;
  margin: 0 0 8px;
  letter-spacing: .5px;
  background: linear-gradient(90deg, var(--accent), var(--accent2));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.subtitle { color: var(--muted); margin: 0; font-size: .95rem; }

.controls {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  justify-content: center;
  margin-bottom: 16px;
}
.card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 10px 14px;
  min-width: 165px;
}
.card > label { display: block; font-size: .8rem; color: var(--muted); margin-bottom: 7px; }
.value { color: var(--accent); font-variant-numeric: tabular-nums; }
.btn-row { display: flex; gap: 8px; flex-wrap: wrap; align-items: center; }

button {
  background: var(--panel2);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 7px 14px;
  font-size: .88rem;
  cursor: pointer;
  transition: border-color .15s, color .15s;
}
button:hover { border-color: var(--accent); color: var(--accent); }
button.danger:hover { border-color: var(--danger); color: var(--danger); }

.checkbox {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: .85rem;
  color: var(--muted);
  cursor: pointer;
  user-select: none;
}
.checkbox input { accent-color: var(--accent); }

input[type="range"] { width: 150px; accent-color: var(--accent); }

.circles-row { display: flex; align-items: center; gap: 8px; }
.circles-row input[type="range"] { flex: 1; min-width: 80px; width: auto; }
.num-input {
  width: 62px;
  background: var(--panel2);
  color: var(--accent);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 4px 6px;
  font-size: .85rem;
  text-align: center;
  font-variant-numeric: tabular-nums;
  font-family: inherit;
  appearance: textfield;
  -moz-appearance: textfield;
}
.num-input::-webkit-outer-spin-button,
.num-input::-webkit-inner-spin-button { -webkit-appearance: none; margin: 0; }
.num-input:focus { outline: none; border-color: var(--accent); }

main { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
@media (max-width: 880px) { main { grid-template-columns: 1fr; } }

.panel {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 14px;
  overflow: hidden;
}
.panel-title {
  padding: 10px 14px;
  font-size: .88rem;
  color: var(--muted);
  border-bottom: 1px solid var(--border);
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 10px;
}
.stats { color: var(--accent); font-variant-numeric: tabular-nums; white-space: nowrap; }

.canvas-wrap { position: relative; height: clamp(320px, 52vh, 560px); background: var(--panel2); }
canvas { position: absolute; inset: 0; display: block; touch-action: none; cursor: crosshair; }
#canvas-epi { cursor: grab; }
#canvas-epi.grabbing { cursor: grabbing; }

.epi-tools {
  position: absolute;
  top: 8px;
  right: 8px;
  display: flex;
  gap: 6px;
  z-index: 2;
}
.tool-btn {
  padding: 4px 11px;
  font-size: .78rem;
  border-radius: 6px;
  background: rgba(14, 19, 28, .85);
}
.tool-btn.active {
  border-color: var(--accent2);
  color: var(--accent2);
}
.epi-hint {
  position: absolute;
  left: 10px;
  bottom: 7px;
  font-size: .72rem;
  color: rgba(139, 150, 168, .55);
  pointer-events: none;
  z-index: 2;
}

.hint {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  color: var(--muted);
  text-align: center;
  pointer-events: none;
  font-size: 1rem;
  line-height: 1.8;
}
.hint span { font-size: .8rem; opacity: .7; }
.hint.hidden { display: none; }

footer { margin-top: 20px; }
details {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 12px 16px;
  color: var(--muted);
  font-size: .9rem;
  line-height: 1.9;
}
summary { cursor: pointer; color: var(--text); font-weight: 600; }