:root {
  --bg: #0f1115;
  --panel: #141824;
  --ink: #e6e8ee;
  --muted: #9aa3b2;
  --accent: #7aa2f7;
  --line: #a5b4fc;        /* soft indigo */
  --line-temp: #60a5fa;   /* brighter while dragging */
  --grid: rgba(255,255,255,.05);
  --shadow: 0 8px 24px rgba(0,0,0,.35);
}

#board {
  position: relative;
  height: calc(100% - 56px);
  min-height: 420px;
  margin: 16px;
  border-radius: 16px;
  background: var(--panel);
  box-shadow: var(--shadow);
  overflow: hidden;
  /* Subtle grid background for spatial context */
  background-image:
    linear-gradient(var(--grid) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid) 1px, transparent 1px);
  background-size: 24px 24px, 24px 24px;
}

#svg {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
}

@media screen and (pointer: fine),screen and (pointer: coarse) and (min-device-width: 601px) {
  /* Style for the live (dragging) line */
  .line--temp {
    stroke: var(--line-temp);
    stroke-width: 3;
    stroke-linecap: round;
    stroke-dasharray: 6 8;
  }
  .line--temp-bg {
    stroke: #000;
    stroke-width: 5;
    stroke-linecap: round;
    stroke-dasharray: 6 8;
  }

  #tooltip {
    position: absolute;
    pointer-events: none;
    padding: 6px 8px;
    border-radius: 8px;
    background: rgba(20, 24, 36, .92);
    color: var(--ink);
    border: 1px solid rgba(122, 162, 247, .25);
    font-size: 20px;
    font-weight: bold;
    line-height: 1;
    transform: translate(12px, -42px);
    display: none;
    white-space: nowrap;
  }
}

@media screen and (pointer: coarse) and (max-device-width: 600px) {
  .line--temp {
    stroke: var(--line-temp);
    stroke-width: 8;
    stroke-linecap: round;
    stroke-dasharray: 16 10;
  }
  .line--temp-bg {
    stroke: #000;
    stroke-width: 10;
    stroke-linecap: round;
    stroke-dasharray: 16 10;
  }

  #tooltip {
    position: absolute;
    pointer-events: none;
    padding: 12px 16px;
    border-radius: 16px;
    background: rgba(20, 24, 36, .92);
    color: var(--ink);
    border: 2px solid rgba(122, 162, 247, .25);
    font-size: 36px;
    font-weight: bold;
    line-height: 1;
    transform: translate(24px, -84px);
    display: none;
    white-space: nowrap;
  }
}