:root {
  --bg: #0f1115;
  --panel: #171a21;
  --panel-2: #1e222b;
  --fg: #e6e8ec;
  --muted: #8a93a6;
  --accent: #f5c26b;
  --accent-2: #ff9ec7;
  --border: #272b35;
  --error: #ff6b6b;
}

* { 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", "Yu Mincho", Meiryo, serif;
  font-size: 15px;
  line-height: 1.6;
}

header {
  padding: 28px 32px 12px;
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: center;
  gap: 8px;
  border-bottom: 1px solid var(--border);
}
header h1 { margin: 0; font-size: 26px; letter-spacing: 0.06em; }
header #subtitle {
  grid-column: 1 / 2;
  margin: 4px 0 0;
  color: var(--muted);
  font-size: 13px;
}
.lang-switch {
  grid-column: 2 / 3;
  grid-row: 1 / 3;
  display: flex;
  align-items: center;
  gap: 6px;
}

main {
  padding: 28px 32px 48px;
  max-width: 900px;
  margin: 0 auto;
}

section { margin-bottom: 28px; }

label {
  display: block;
  font-size: 13px;
  color: var(--muted);
  margin-bottom: 8px;
}

h2 {
  font-size: 12px;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-weight: 600;
  margin: 0 0 12px;
}

input[type="text"] {
  width: 100%;
  padding: 14px 18px;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 10px;
  color: var(--fg);
  font-family: "SF Mono", Menlo, Consolas, monospace;
  font-size: 18px;
}
input[type="text"]:focus { outline: none; border-color: var(--accent); }

select {
  padding: 8px 10px;
  background: var(--panel-2);
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--fg);
  font-size: 13px;
  font-family: inherit;
}

.error {
  margin-top: 10px;
  color: var(--error);
  font-family: "SF Mono", Menlo, Consolas, monospace;
  font-size: 13px;
}

.result {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 20px 24px;
}
.result-row {
  display: flex;
  align-items: baseline;
  padding: 10px 0;
  border-bottom: 1px dashed var(--border);
}
.result-row:last-child { border-bottom: none; }
.result-label {
  width: 120px;
  color: var(--muted);
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-weight: 600;
}
.result-value {
  flex: 1;
  font-size: 22px;
  color: var(--accent);
  font-weight: 500;
  letter-spacing: 0.04em;
}

.era-list {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 14px 18px;
}
.era-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 8px 0;
  border-bottom: 1px dashed var(--border);
}
.era-row:last-child { border-bottom: none; }
.era-name {
  font-size: 16px;
  color: var(--fg);
}
.era-dates {
  font-family: "SF Mono", Menlo, Consolas, monospace;
  font-size: 13px;
  color: var(--muted);
}

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