:root {
  --bg: #0f1115;
  --panel: #171a21;
  --panel-2: #1e222b;
  --fg: #e6e8ec;
  --muted: #8a93a6;
  --accent: #7cc4ff;
  --accent-2: #9ae6b4;
  --border: #272b35;
  --red: #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", 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: 800px;
  margin: 0 auto;
}

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

h2 {
  font-size: 12px;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  font-weight: 600;
  margin: 0 0 12px;
}

label {
  display: block;
  font-size: 12px;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 4px;
}

input[type="number"] {
  padding: 12px 16px;
  background: var(--panel-2);
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--fg);
  font-family: "SF Mono", Menlo, Consolas, monospace;
  font-size: 20px;
  width: 140px;
}
input[type="number"]: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;
}

.leap-result {
  margin-top: 14px;
  padding: 14px 16px;
  border-radius: 8px;
  font-size: 20px;
  font-weight: 600;
  text-align: center;
}
.leap-result.yes {
  background: rgba(154, 230, 180, 0.1);
  color: var(--accent-2);
  border: 1px solid rgba(154, 230, 180, 0.3);
}
.leap-result.no {
  background: rgba(138, 147, 166, 0.1);
  color: var(--muted);
  border: 1px solid var(--border);
}

.next-leap {
  margin-top: 10px;
  font-size: 14px;
  color: var(--muted);
}
.next-leap strong {
  color: var(--accent);
  font-family: "SF Mono", Menlo, Consolas, monospace;
  font-size: 16px;
}

.range-inputs {
  display: flex;
  gap: 12px;
  align-items: flex-end;
  flex-wrap: wrap;
  margin-bottom: 14px;
}

.range-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.year-chip {
  padding: 6px 12px;
  background: var(--panel-2);
  border: 1px solid var(--border);
  border-radius: 999px;
  font-family: "SF Mono", Menlo, Consolas, monospace;
  font-size: 13px;
  color: var(--fg);
}
.year-chip.current {
  background: var(--accent);
  color: #0b1320;
  border-color: var(--accent);
  font-weight: 700;
}

.leap-seconds-total {
  margin-bottom: 10px;
  color: var(--muted);
  font-size: 13px;
}
.leap-seconds-total strong {
  color: var(--accent);
  font-family: "SF Mono", Menlo, Consolas, monospace;
  font-size: 16px;
}

.leap-seconds-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
  gap: 6px;
  max-height: 280px;
  overflow-y: auto;
}
.leap-second-row {
  display: flex;
  justify-content: space-between;
  padding: 6px 12px;
  background: var(--panel-2);
  border-radius: 4px;
  font-family: "SF Mono", Menlo, Consolas, monospace;
  font-size: 12px;
}
.leap-second-row .delta { color: var(--accent-2); }

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