:root {
  --panel-w: 340px;
  --bg: #0f1419;
  --panel: #171d26;
  --card: #1e2733;
  --ink: #e7eef6;
  --muted: #9fb0c3;
  --accent: #4aa3ff;
  --warn: #ffb454;
  --danger: #ff6b6b;
}

* { box-sizing: border-box; }
html, body { margin: 0; height: 100%; }
body {
  font: 14px/1.45 system-ui, -apple-system, Segoe UI, Roboto, sans-serif;
  color: var(--ink);
  background: var(--bg);
}

#app { display: flex; height: 100vh; }
#map { flex: 1; height: 100%; }
/* slate fallback shown only until/if basemap tiles load */
.leaflet-container { background: #16222e; }

#panel {
  width: var(--panel-w);
  flex: none;
  background: var(--panel);
  padding: 16px 16px 24px;
  overflow-y: auto;
  border-left: 1px solid #0a0e13;
}

#panel h1 { font-size: 18px; margin: 0 0 4px; }
#panel h2 { font-size: 13px; text-transform: uppercase; letter-spacing: .06em;
  color: var(--muted); margin: 20px 0 8px; border-bottom: 1px solid #2a3543;
  padding-bottom: 6px; }
#panel h2 small { text-transform: none; letter-spacing: 0; }
.sub { color: var(--muted); font-size: 12.5px; margin: 0 0 14px; }

.control label { display: block; margin-bottom: 6px; font-weight: 600; }
.control output { color: var(--accent); }
input[type=range] { width: 100%; accent-color: var(--accent); }

.readout { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; margin-top: 14px; }
.readout > div { background: var(--card); border-radius: 8px; padding: 8px 10px; }
.readout span { display: block; color: var(--muted); font-size: 11px; }
.readout b { font-size: 15px; }

.stats { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; }
.stats > div { background: var(--card); border-radius: 8px; padding: 10px; }
.stats span { display: block; color: var(--muted); font-size: 11px; }
.stats b { font-size: 20px; font-variant-numeric: tabular-nums; }
.stats i { color: var(--muted); font-style: normal; font-size: 11px; margin-left: 4px; }

.exports { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; }
.exports button {
  background: var(--accent); color: #06121f; border: 0; border-radius: 8px;
  padding: 9px; font-weight: 700; cursor: pointer;
}
.exports button:disabled { background: #2a3543; color: #5d6b7c; cursor: default; }
.hint { color: var(--muted); font-size: 11.5px; margin: 8px 0 0; }

.warn {
  background: rgba(255,180,84,.12); border: 1px solid var(--warn);
  color: var(--warn); border-radius: 8px; padding: 8px 10px; font-size: 12px;
  margin-bottom: 12px;
}
.warn.danger { background: rgba(255,107,107,.12); border-color: var(--danger);
  color: var(--danger); }
.hidden { display: none; }
#warnings:empty { display: none; }
#warnings { margin-top: 12px; display: grid; gap: 8px; }

.caveats { margin-top: 18px; background: var(--card); border-radius: 8px; padding: 10px 12px; }
.caveats summary { cursor: pointer; font-weight: 600; }
.caveats ul { margin: 8px 0 0; padding-left: 18px; color: var(--muted); font-size: 12px; }
.caveats li { margin-bottom: 5px; }
code { background: #0a0e13; padding: 1px 5px; border-radius: 4px; font-size: 12px; }

.foot { color: #5d6b7c; font-size: 11px; margin-top: 16px; }

/* dam handles + labels */
.dam-handle {
  width: 16px; height: 16px; border-radius: 50%;
  background: #ffd54a; border: 3px solid #1a1a1a; box-shadow: 0 0 0 2px #ffd54a55;
  cursor: grab;
}
.dam-handle:active { cursor: grabbing; }
.pin-label {
  background: rgba(15,20,25,.82); color: #fff; padding: 2px 6px; border-radius: 4px;
  font-size: 11px; white-space: nowrap; border: 1px solid #2a3543;
}

#loading {
  position: fixed; inset: 0; background: var(--bg); display: flex;
  align-items: center; justify-content: center; gap: 12px; z-index: 9999;
  color: var(--muted);
}
.spinner {
  width: 22px; height: 22px; border: 3px solid #2a3543; border-top-color: var(--accent);
  border-radius: 50%; animation: spin .8s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }

@media (max-width: 720px) {
  #app { flex-direction: column-reverse; }
  #panel { width: 100%; max-height: 48vh; }
}