:root {
  --bg: #f4f6f8;
  --card: #ffffff;
  --text: #1d2733;
  --muted: #5f6b78;
  --accent: #1f77b4;
  --warning: #c27c0e;
  --border: #dde3ea;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #11161c;
    --card: #1a2129;
    --text: #e6edf3;
    --muted: #9aa7b4;
    --accent: #5aa9e6;
    --warning: #f0b44c;
    --border: #2a333d;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
}

main {
  max-width: 960px;
  margin: 0 auto;
  padding: 16px;
}

header {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  margin: 8px 0 16px;
}

h1 { font-size: 1.4rem; font-weight: 600; margin: 0; }

.lang { display: flex; gap: 4px; }
.lang button {
  border: 1px solid var(--border);
  background: var(--card);
  color: var(--muted);
  border-radius: 8px;
  padding: 4px 10px;
  font: inherit;
  font-size: 0.9rem;
  cursor: pointer;
}
.lang button[aria-pressed="true"] {
  color: var(--text);
  border-color: var(--accent);
  font-weight: 600;
}
h2 { font-size: 1rem; font-weight: 600; margin: 0 0 8px; color: var(--muted); }

section {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 16px;
  margin-bottom: 16px;
}

.current { text-align: center; }

.current-value {
  display: inline-flex;
  align-items: baseline;
  gap: 6px;
  font-variant-numeric: tabular-nums;
}

#level { font-size: 4.5rem; font-weight: 700; line-height: 1; color: var(--accent); }
.unit { font-size: 1.5rem; color: var(--muted); }

.age { margin-top: 8px; color: var(--muted); }

.warning {
  align-self: flex-start;
  margin-left: 8px;
  border: none;
  background: none;
  color: var(--warning);
  font-size: 1.8rem;
  cursor: pointer;
  padding: 0 4px;
}

.warning-text {
  margin: 12px auto 0;
  max-width: 480px;
  padding: 8px 12px;
  border: 1px solid var(--warning);
  border-radius: 8px;
  color: var(--warning);
  text-align: left;
}
.warning-text p { margin: 4px 0; }

.chart { width: 100%; height: 360px; }

footer { color: var(--muted); font-size: 0.85rem; text-align: center; padding: 8px 0 24px; }

@media (max-width: 600px) {
  #level { font-size: 3.5rem; }
  .chart { height: 300px; }
}