:root {
  --bg: #fdf7e8; --panel: #fffdf6; --ink: #3a2f1c; --muted: #7b6a4c;
  --line: #e0d2b0; --accent: #1f6f8b; --accent2: #c0622b; --ok: #2f7d4f; --bad: #c0392b;
  --shadow: 0 1px 2px rgba(60,44,18,.10), 0 6px 18px rgba(60,44,18,.06);
}
:root[data-theme="dark"] {
  --bg: #1b1710; --panel: #241f17; --ink: #ede2cc; --muted: #a2926f;
  --line: #3b3325; --accent: #6fc0da; --accent2: #e8955f; --ok: #6cc08c; --bad: #e57a6c;
  --shadow: 0 1px 2px rgba(0,0,0,.35), 0 6px 18px rgba(0,0,0,.25);
}
* { box-sizing: border-box; }
body {
  margin: 0; background: var(--bg); color: var(--ink);
  font: 15px/1.55 ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}
a { color: var(--accent); }
.top {
  display: flex; flex-wrap: wrap; gap: 12px; align-items: flex-end; justify-content: space-between;
  padding: 16px 20px 12px; border-bottom: 1px solid var(--line); background: var(--panel);
}
h1 { margin: 0; font-size: 26px; letter-spacing: -0.01em; }
.tag { margin: 2px 0 0; color: var(--muted); font-size: 13px; }
.topright { display: flex; gap: 10px; align-items: center; flex-wrap: wrap; }
.tabs { display: flex; gap: 4px; }
button { font: inherit; }
.tab, .ghost, .toolbtn, .btnrow button {
  border: 1px solid var(--line); background: var(--panel); color: var(--ink);
  border-radius: 8px; padding: 6px 12px; cursor: pointer;
}
.tab.on, .toolbtn.on { background: var(--accent); border-color: var(--accent); color: #fff; }
.btnrow button.primary { background: var(--accent); border-color: var(--accent); color: #fff; }
.tab:hover, .ghost:hover, .toolbtn:hover, .btnrow button:hover { border-color: var(--accent); }
main { padding: 16px 20px 40px; max-width: 1180px; margin: 0 auto; }
.panel[hidden] { display: none !important; }
h2 { font-size: 16px; margin: 18px 0 8px; }
.beachwrap { background: var(--panel); border: 1px solid var(--line); border-radius: 12px; padding: 10px; box-shadow: var(--shadow); position: relative; }
canvas#beach { width: 100%; height: auto; display: block; border-radius: 8px; cursor: crosshair; touch-action: pan-y; }
.hud {
  position: absolute; top: 18px; left: 20px; display: flex; gap: 10px;
  font: 12px/1 ui-monospace, SFMono-Regular, Menlo, monospace;
  background: rgba(255,253,246,.82); color: #3a2f1c; padding: 6px 9px; border-radius: 7px;
}
.ghostinfo { margin: 8px 2px 0; font: 12px/1.4 ui-monospace, SFMono-Regular, Menlo, monospace; color: var(--muted); min-height: 2.6em; }
.controls { display: grid; grid-template-columns: repeat(auto-fit, minmax(230px, 1fr)); gap: 14px; margin-top: 14px; }
.ctrlgroup { background: var(--panel); border: 1px solid var(--line); border-radius: 12px; padding: 12px; box-shadow: var(--shadow); }
.lab { display: block; font-size: 12px; font-weight: 600; color: var(--muted); margin-bottom: 6px; text-transform: uppercase; letter-spacing: .04em; }
.lab output { font-weight: 400; text-transform: none; letter-spacing: 0; color: var(--ink); }
.tools { display: flex; flex-wrap: wrap; gap: 6px; }
.hint { font-size: 12px; color: var(--muted); margin: 8px 0 0; }
input[type=range] { width: 100%; accent-color: var(--accent); }
select { width: 100%; padding: 6px; border-radius: 8px; border: 1px solid var(--line); background: var(--panel); color: var(--ink); margin-bottom: 8px; }
.btnrow { display: flex; flex-wrap: wrap; gap: 6px; }
.readout { margin-top: 16px; background: var(--panel); border: 1px solid var(--line); border-radius: 12px; padding: 12px 16px; box-shadow: var(--shadow); }
dl { display: grid; grid-template-columns: minmax(160px, 30%) 1fr; gap: 4px 14px; margin: 0; font-size: 13px; }
dt { color: var(--muted); }
dd { margin: 0; }
.log { list-style: none; padding: 0; margin: 0; font: 12px/1.6 ui-monospace, SFMono-Regular, Menlo, monospace; }
.log li { border-bottom: 1px dotted var(--line); padding: 2px 0; }
.muted { color: var(--muted); }
.finding { background: var(--panel); border: 1px solid var(--line); border-left: 4px solid var(--accent2); border-radius: 12px; padding: 12px 16px; box-shadow: var(--shadow); }
blockquote { margin: 6px 0; font-size: 17px; font-style: italic; color: var(--muted); }
.figs { display: grid; grid-template-columns: repeat(auto-fit, minmax(min(330px, 100%), 1fr)); gap: 14px; margin-top: 16px; }
figure { margin: 0; background: var(--panel); border: 1px solid var(--line); border-radius: 12px; padding: 10px; box-shadow: var(--shadow); }
figure canvas { width: 100%; height: auto; display: block; border-radius: 8px; }
figcaption { font-size: 12px; color: var(--muted); margin-top: 8px; }
.labctrl { margin-top: 16px; }
#panel-help ol, #panel-help ul { padding-left: 20px; }
#panel-help li { margin: 5px 0; }
#findingBody p { margin: 9px 0; max-width: 78ch; }
.foot { border-top: 1px solid var(--line); padding: 14px 20px; display: flex; gap: 14px; flex-wrap: wrap; color: var(--muted); font-size: 12px; }
@media (max-width: 640px) {
  dl { grid-template-columns: 1fr; } dt { margin-top: 6px; }
  /* On a phone the canvas is ~110 px tall; an overlaid HUD would cover a third of it. */
  .hud { position: static; flex-wrap: wrap; gap: 4px 10px; background: none; color: var(--ink); padding: 0 2px 6px; }
}