:root {
  color-scheme: light;
  --surface-0:      #ffffff;
  --surface-1:      #fcfcfb;
  --surface-2:      #f2f1ee;
  --border:         #e2e0da;
  --text-primary:   #0b0b0b;
  --text-secondary: #52514e;
  --text-muted:     #85837c;

  --series-1: #2a78d6; /* blue   -- System A slot */
  --series-2: #eb6834; /* orange -- System B slot */
  --series-3: #1baf7a; /* aqua */
  --series-4: #eda100; /* yellow */
  --series-5: #e87ba4; /* magenta */
  --series-6: #008300; /* green */
  --series-7: #4a3aa7; /* violet */
  --series-8: #e34948; /* red */
}

@media (prefers-color-scheme: dark) {
  :root:where(:not([data-theme="light"])) {
    color-scheme: dark;
    --surface-0:      #111110;
    --surface-1:      #1a1a19;
    --surface-2:      #232320;
    --border:         #34332e;
    --text-primary:   #ffffff;
    --text-secondary: #c3c2b7;
    --text-muted:     #8b8a80;

    --series-1: #3987e5;
    --series-2: #d95926;
    --series-3: #199e70;
    --series-4: #c98500;
    --series-5: #d55181;
    --series-6: #008300;
    --series-7: #9085e9;
    --series-8: #e66767;
  }
}
:root[data-theme="dark"] {
  color-scheme: dark;
  --surface-0:      #111110;
  --surface-1:      #1a1a19;
  --surface-2:      #232320;
  --border:         #34332e;
  --text-primary:   #ffffff;
  --text-secondary: #c3c2b7;
  --text-muted:     #8b8a80;

  --series-1: #3987e5;
  --series-2: #d95926;
  --series-3: #199e70;
  --series-4: #c98500;
  --series-5: #d55181;
  --series-6: #008300;
  --series-7: #9085e9;
  --series-8: #e66767;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--surface-0);
  color: var(--text-primary);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.4;
}

.site-nav {
  display: flex; gap: 1rem;
  padding: 0.75rem 1.5rem 0;
}
.site-nav a { color: #0000EE; text-decoration: none; font-size: 0.9rem; }
.site-nav a:visited { color: #551A8B; }
.site-nav a:hover { text-decoration: underline; }

.page-header {
  display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between;
  gap: 1rem; padding: 1rem 1.5rem; border-bottom: 1px solid var(--border);
}
.page-header h1 { font-size: 1.25rem; margin: 0; }
.title-row { display: flex; align-items: baseline; gap: 1rem; }
.sources-link { font-size: 0.85rem; color: var(--text-secondary); text-decoration: none; }
.sources-link:hover { text-decoration: underline; color: var(--text-primary); }
.pickers { display: flex; gap: 1.5rem; flex-wrap: wrap; }
.pickers label { display: flex; flex-direction: column; gap: 0.25rem; font-size: 0.8rem; color: var(--text-secondary); }
.pickers select {
  font-size: 0.95rem; padding: 0.35rem 0.5rem; border-radius: 6px;
  border: 1px solid var(--border); background: var(--surface-1); color: var(--text-primary);
}

main { max-width: 1200px; margin: 0 auto; padding: 1rem 1.5rem 3rem; }

.panel { margin-top: 2rem; }
.panel h2 { font-size: 1.05rem; margin: 0 0 0.75rem; display: flex; align-items: baseline; gap: 0.6rem; }
.hint { font-size: 0.78rem; font-weight: 400; color: var(--text-muted); }

.legend { display: flex; gap: 1.25rem; margin-bottom: 0.5rem; font-size: 0.85rem; color: var(--text-secondary); }
.legend .swatch { display: inline-flex; align-items: center; gap: 0.4rem; }
.legend .dot { width: 10px; height: 10px; border-radius: 50%; display: inline-block; }

.overlay-wrap, .compare-wrap {
  background: var(--surface-1); border: 1px solid var(--border); border-radius: 10px; padding: 0.5rem;
}

.detail-grid { display: flex; flex-direction: column; gap: 1.5rem; }

.system-card { background: var(--surface-1); border: 1px solid var(--border); border-radius: 10px; padding: 1rem; }
.system-card h3 { margin: 0 0 0.5rem; font-size: 1rem; }
.system-card .map-wrap { background: var(--surface-0); border-radius: 8px; border: 1px solid var(--border); }

.stat-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 0.6rem; margin: 0.9rem 0; }
@media (max-width: 560px) { .stat-grid { grid-template-columns: repeat(2, 1fr); } }
.stat-tile { background: var(--surface-2); border-radius: 8px; padding: 0.5rem 0.6rem; }
.stat-tile .v { font-size: 1.05rem; font-weight: 600; color: var(--text-primary); }
.stat-tile .l { font-size: 0.7rem; color: var(--text-muted); text-transform: uppercase; letter-spacing: 0.03em; }

.examples-row { display: grid; grid-template-columns: repeat(4, 1fr); gap: 0.5rem; }
@media (max-width: 560px) { .examples-row { grid-template-columns: repeat(2, 1fr); } }
/* min-width: 0 overrides the grid default (auto, i.e. content's max-content size) -- without
   it, .names' nowrap text forces this tile's whole column wider than its 1fr share whenever a
   station-pair name is long, throwing off alignment against the other column in the row. */
.example-tile { text-align: center; min-width: 0; }
.example-tile .cap { font-size: 0.72rem; color: var(--text-muted); text-transform: uppercase; letter-spacing: 0.03em; }
.example-tile .len { font-size: 0.85rem; font-weight: 600; }
.example-tile .names { font-size: 0.68rem; color: var(--text-secondary); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }

svg text { fill: var(--text-secondary); font-size: 11px; }
/* Keeps line thickness constant in screen pixels as the zoom-layer's transform scales --
   vector-effect isn't inherited, so this has to target the paths directly, not their <g>. */
.zoom-layer path { vector-effect: non-scaling-stroke; }
.tooltip {
  position: absolute; pointer-events: none; background: var(--surface-2); border: 1px solid var(--border);
  border-radius: 6px; padding: 0.4rem 0.6rem; font-size: 0.78rem; color: var(--text-primary);
  box-shadow: 0 4px 12px rgba(0,0,0,0.15); opacity: 0; transition: opacity 0.1s; z-index: 10;
}

.page-footer { max-width: 1200px; margin: 0 auto; padding: 1rem 1.5rem 2rem; font-size: 0.78rem; color: var(--text-muted); }