:root {
  --bg: #0b0b0f;
  --panel-bg: color-mix(in oklab, #0b0b0f 70%, white 0%);
  --panel-border: color-mix(in oklab, #ffffff 12%, #0b0b0f 88%);
  --text: #e8e8ef;
  --muted: #a8abb6;
  --accent: #7f5af0;
  --accent-2: #2cb67d;
  --shadow: 0 10px 30px rgba(0,0,0,.35);
}

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

html, body {
  height: 100%;
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, PingFang SC, Hiragino Sans GB, Noto Sans CJK SC, Microsoft YaHei, "Helvetica Neue", Arial, "Noto Sans", sans-serif, "Apple Color Emoji", "Segoe UI Emoji";
}

#canvas {
  position: fixed;
  inset: 0;
  width: 100%;
  height: 100%;
  display: block;
  background: var(--bg);
  touch-action: none;
  cursor: crosshair;
}

#panel {
  position: fixed;
  top: env(safe-area-inset-top, 16px);
  left: env(safe-area-inset-left, 16px);
  width: min(92vw, 380px);
  max-height: calc(100dvh - 32px);
  overflow: auto;
  background: rgba(20, 20, 28, 0.6);
  backdrop-filter: blur(12px) saturate(120%);
  border: 1px solid var(--panel-border);
  border-radius: 14px;
  box-shadow: var(--shadow);
}

.panel-header {
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: center;
  padding: 12px 14px 6px 14px;
  position: sticky;
  top: 0;
  background: inherit;
  backdrop-filter: inherit;
  border-bottom: 1px solid color-mix(in oklab, var(--panel-border), transparent 40%);
}

.panel-header h1 {
  font-size: 16px;
  margin: 0;
  letter-spacing: 0.2px;
}

.icon-btn {
  appearance: none;
  border: 1px solid var(--panel-border);
  background: transparent;
  color: var(--text);
  border-radius: 8px;
  padding: 6px 8px;
  cursor: pointer;
}

.controls {
  padding: 12px 14px 16px 14px;
  display: grid;
  gap: 10px;
}

.group {
  display: grid;
  gap: 6px;
}

.group label {
  font-size: 12px;
  color: var(--muted);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

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

.checkbox {
  display: inline-flex;
  gap: 8px;
  align-items: center;
  font-size: 13px;
}

select, input[type="color"], input[type="range"] {
  width: 100%;
  appearance: none;
  background: rgba(255,255,255,0.06);
  border: 1px solid var(--panel-border);
  color: var(--text);
  padding: 8px;
  border-radius: 10px;
}

input[type="color"] {
  padding: 2px;
  height: 36px;
}

select {
  height: 36px;
}

.buttons {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: 8px;
}

.btn {
  appearance: none;
  border: 1px solid var(--panel-border);
  color: var(--text);
  background: rgba(255,255,255,0.06);
  border-radius: 10px;
  padding: 10px 12px;
  cursor: pointer;
  transition: transform .05s ease, background .2s ease, border-color .2s ease;
}

.btn:hover {
  background: rgba(255,255,255,0.10);
  border-color: color-mix(in oklab, var(--panel-border), white 12%);
}

.btn:active {
  transform: translateY(1px);
}

.btn.primary {
  background: color-mix(in oklab, var(--accent) 20%, white 8%);
  border-color: color-mix(in oklab, var(--accent), white 10%);
}

.divider {
  height: 1px;
  background: color-mix(in oklab, var(--panel-border), transparent 40%);
  margin: 6px 0;
}

.hint {
  margin: 4px 0 0;
  color: var(--muted);
  font-size: 12px;
  line-height: 1.4;
  opacity: .9;
}

/* narrow screen tweaks */
@media (max-width: 560px) {
  #panel {
    width: calc(100vw - 20px);
    left: 10px;
    right: 10px;
    top: auto;
    bottom: 10px;
    max-height: 62dvh;
  }
  .buttons {
    grid-template-columns: 1fr 1fr;
  }
}