:root,
:root[data-theme="light"] {
  --bg: #ffffff;
  --fg: #1a1a1a;
  --muted: #666;
  --border: #ddd;
}
:root[data-theme="dark"] {
  --bg: #14161a;
  --fg: #e8e8e8;
  --muted: #9aa0a6;
  --border: #2a2e35;
}

* { box-sizing: border-box; }
body {
  margin: 0;
  font: 15px/1.4 system-ui, -apple-system, Segoe UI, Roboto, sans-serif;
  background: var(--bg);
  color: var(--fg);
}
header {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 1rem;
  padding: 0.75rem 1rem;
  border-bottom: 1px solid var(--border);
}
h1 { font-size: 1.1rem; margin: 0; }
header h1 a { color: inherit; text-decoration: none; }
.header-right { display: flex; flex-wrap: wrap; align-items: center; gap: 1rem; margin-left: auto; }
.controls { display: flex; gap: 1rem; }
label { color: var(--muted); font-size: 0.9rem; }
select {
  background: var(--bg);
  color: var(--fg);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 0.25rem 0.4rem;
}
.theme-toggle {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  background: var(--bg);
  color: var(--fg);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 0.25rem 0.6rem;
  font: inherit;
  cursor: pointer;
}
.theme-toggle .icon { width: 16px; height: 16px; }

.err { color: #c0392b; padding: 0 1rem; min-height: 1rem; }
.chart-wrap {
  height: 70vh;
  padding: 1rem;
}