/* Diagram-style layout: white nodes with 2px role-coloured strokes,
   dashed boundaries, labelled edges. All spacing on a 4px grid. */
:root {
  --primary: #1dafec;   /* main focus nodes */
  --platform: #002f6c;  /* core / structural */
  --aux: #00a3ad;       /* auxiliary */
  --text: #1a1f2c;
  --muted: #5a6475;
  --surface: #f4f7fa;
  --border: #d0d7de;
  --card: #ffffff;
  --mono: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
}

* { box-sizing: border-box; }
body {
  margin: 0;
  background: var(--surface);
  background-image: radial-gradient(var(--border) 1px, transparent 1px);
  background-size: 24px 24px;
  color: var(--text);
  font: 16px/24px system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
}
a { color: inherit; }
h1, h2, h3, p { margin: 0; }

.canvas { max-width: 1040px; margin: 0 auto; padding: 48px 24px; display: flex; flex-direction: column; align-items: center; }

/* Nodes */
.node {
  background: var(--card);
  border: 2px solid var(--border);
  border-radius: 8px;
  padding: 16px;
  display: flex; flex-direction: column; gap: 8px;
}
.node h3 { font-size: 16px; line-height: 24px; font-weight: 600; }
.node h3 a { text-decoration: none; }
.node h3 a:hover { text-decoration: underline; text-underline-offset: 4px; }
.node p { font-size: 14px; line-height: 20px; color: var(--muted); }
.node--primary  { border-color: var(--primary); }
.node--platform { border-color: var(--platform); }
.node--aux      { border-color: var(--aux); }

.node__kind { font: 12px/16px var(--mono); text-transform: uppercase; letter-spacing: 0.08em; color: var(--muted); }
.node__ports { display: flex; flex-wrap: wrap; gap: 4px; margin-top: auto; }
.node__ports code, .node__ports a {
  font: 12px/16px var(--mono);
  padding: 0 8px; border: 2px solid var(--border); border-radius: 4px;
  background: var(--surface); color: var(--text); text-decoration: none;
}
.node__ports a:hover { border-color: var(--primary); }

.node--root { width: 100%; max-width: 560px; border-color: var(--platform); border-width: 4px; padding: 24px; text-align: center; align-items: center; }
.node--root h1 { font-size: 24px; line-height: 32px; }
.node--root p { font-size: 16px; line-height: 24px; }

/* Edges: vertical connector with arrowhead and label */
.edge { position: relative; z-index: 1; height: 48px; margin-bottom: 16px; width: 2px; background: var(--primary); }
.edge::after {
  content: ""; position: absolute; bottom: -2px; left: -5px;
  border: 6px solid transparent; border-top: 8px solid var(--primary); border-bottom: 0;
}
.edge span {
  position: absolute; top: 20px; left: 12px; white-space: nowrap;
  font: 12px/16px var(--mono); color: var(--muted); background: var(--surface); padding: 0 4px;
}

/* Boundaries (subgraphs) */
.groups { width: 100%; display: grid; grid-template-columns: repeat(auto-fit, minmax(min(300px, 100%), 1fr)); gap: 24px; align-items: start; }
.boundary {
  width: 100%; position: relative;
  border: 2px dashed var(--border); border-radius: 12px;
  background: rgba(244, 247, 250, 0.88);
  padding: 32px 16px 16px;
}
.boundary__label {
  position: absolute; top: -12px; left: 16px;
  font: 600 12px/20px var(--mono); text-transform: uppercase; letter-spacing: 0.08em;
  color: var(--platform); background: var(--surface); padding: 0 8px;
}
.nodes, .flow { list-style: none; margin: 0; padding: 0; display: grid; gap: 12px; }
.flow { grid-template-columns: repeat(auto-fill, minmax(min(280px, 100%), 1fr)); }

/* Legend */
.legend {
  width: 100%; margin-top: 48px; padding-top: 16px; border-top: 2px solid var(--border);
  display: flex; flex-wrap: wrap; gap: 16px; align-items: center;
  font: 12px/16px var(--mono); color: var(--muted);
}
.key::before { content: ""; display: inline-block; width: 12px; height: 12px; margin-right: 8px; vertical-align: -2px; border: 2px solid; border-radius: 4px; background: var(--card); }
.key--primary::before  { border-color: var(--primary); }
.key--platform::before { border-color: var(--platform); }
.key--aux::before      { border-color: var(--aux); }
.legend__meta { margin-left: auto; }

@media (max-width: 640px) {
  .canvas { padding: 32px 16px; }
  .legend__meta { margin-left: 0; width: 100%; }
}