:root {
  --bg-a: #f5f7ef;
  --bg-b: #ecefe2;
  --panel: rgba(255, 255, 255, 0.9);
  --line: rgba(24, 28, 33, 0.16);
  --ink: #1f2630;
  --ink-soft: #5a6674;
  --accent: #0f8b7b;
  --accent-2: #d56a42;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: "Trebuchet MS", "Segoe UI", sans-serif;
  color: var(--ink);
  background:
    radial-gradient(circle at 15% 5%, rgba(15, 139, 123, 0.2), transparent 28%),
    radial-gradient(circle at 85% 90%, rgba(213, 106, 66, 0.18), transparent 32%),
    linear-gradient(180deg, var(--bg-a), var(--bg-b));
}

.app-shell {
  width: min(1240px, calc(100vw - 32px));
  margin: 20px auto;
  display: grid;
  gap: 12px;
}

.hero,
.board-panel {
  border: 1px solid var(--line);
  border-radius: 18px;
  background: var(--panel);
  box-shadow: 0 16px 34px rgba(20, 24, 28, 0.1);
}

.hero {
  padding: 16px;
}

.hero h1 {
  margin: 0;
  font-size: clamp(1.5rem, 4vw, 2.3rem);
}

.hero p {
  margin: 8px 0 0;
  color: var(--ink-soft);
}

.actions {
  margin-top: 12px;
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

button {
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 8px 12px;
  background: #fff;
  color: var(--ink);
  font-weight: 700;
  cursor: pointer;
}

button:hover {
  border-color: rgba(24, 28, 33, 0.28);
}

.status {
  margin-top: 10px;
  font-family: Consolas, monospace;
  font-size: 0.85rem;
}

.board-panel {
  padding: 12px;
}

#board {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 14px;
  background:
    linear-gradient(to right, rgba(24, 28, 33, 0.04) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(24, 28, 33, 0.04) 1px, transparent 1px),
    #fff;
  background-size: 36px 36px;
}

.link-line {
  stroke: rgba(24, 28, 33, 0.4);
  stroke-width: 2;
}

.node {
  cursor: pointer;
}

.node circle {
  fill: #fff;
  stroke: var(--accent);
  stroke-width: 3;
}

.node.selected circle {
  stroke: var(--accent-2);
}

.node text {
  fill: var(--ink);
  font-size: 13px;
  text-anchor: middle;
  dominant-baseline: central;
  pointer-events: none;
}

@media (max-width: 760px) {
  .app-shell {
    width: min(1240px, calc(100vw - 18px));
    margin-top: 10px;
  }
}