:root {
  --bg: #0f1115;
  --panel: #171a21;
  --panel-2: #1e222b;
  --fg: #e6e8ec;
  --muted: #8a93a6;
  --accent: #9ae6b4;
  --border: #272b35;
  --source-bg: #1a2838;
  --source-border: #3b7bbf;
}

* { box-sizing: border-box; }

html, body {
  margin: 0; padding: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Sans",
    "Hiragino Kaku Gothic ProN", Meiryo, sans-serif;
  font-size: 15px;
  line-height: 1.6;
}

header {
  padding: 24px 32px 8px;
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: center;
  gap: 8px;
  border-bottom: 1px solid var(--border);
}
header h1 { margin: 0; font-size: 22px; }
header #subtitle {
  grid-column: 1 / 2;
  margin: 4px 0 0;
  color: var(--muted);
  font-size: 14px;
}
.lang-switch {
  grid-column: 2 / 3;
  grid-row: 1 / 3;
  display: flex;
  align-items: center;
  gap: 6px;
}

main {
  padding: 24px 32px 48px;
  max-width: 900px;
  margin: 0 auto;
}

.input-section {
  display: flex;
  gap: 14px;
  margin-bottom: 24px;
  flex-wrap: wrap;
}
.field { flex: 1; min-width: 200px; }

label {
  display: block;
  font-size: 12px;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 6px;
}

input[type="number"], select {
  width: 100%;
  padding: 12px 16px;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--fg);
  font-family: "SF Mono", Menlo, Consolas, monospace;
  font-size: 18px;
}
select {
  font-family: -apple-system, BlinkMacSystemFont, "Hiragino Sans", sans-serif;
}
input:focus, select:focus { outline: none; border-color: var(--accent); }

.card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 20px 24px;
}

h2 {
  font-size: 12px;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin: 0 0 14px;
}

.grid {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.unit-row {
  display: grid;
  grid-template-columns: 1fr 100px auto;
  gap: 16px;
  align-items: baseline;
  padding: 10px 14px;
  background: var(--panel-2);
  border: 1px solid var(--border);
  border-radius: 6px;
}
.unit-row.source {
  background: var(--source-bg);
  border-color: var(--source-border);
}

.unit-label {
  color: var(--fg);
  font-size: 14px;
}
.unit-symbol {
  color: var(--muted);
  font-size: 12px;
  font-family: "SF Mono", Menlo, Consolas, monospace;
}
.unit-value {
  color: var(--accent);
  font-family: "SF Mono", Menlo, Consolas, monospace;
  font-size: 16px;
  font-weight: 600;
  text-align: right;
}
.unit-row.source .unit-value { font-weight: 700; }

footer {
  padding: 24px 32px;
  border-top: 1px solid var(--border);
  color: var(--muted);
  font-size: 12px;
  text-align: center;
}