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

* { 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: 1100px;
  margin: 0 auto;
}

.fields {
  display: grid;
  grid-template-columns: 1fr;
  gap: 14px;
  margin-bottom: 24px;
}
@media (min-width: 700px) {
  .fields { grid-template-columns: 1fr 1fr; }
}

.field-card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 16px 18px;
}

.field-label {
  font-size: 12px;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-weight: 600;
  margin-bottom: 10px;
}

.mode-row {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
  margin-bottom: 10px;
}

.mode-btn {
  padding: 4px 10px;
  background: var(--panel-2);
  border: 1px solid var(--border);
  border-radius: 999px;
  color: var(--muted);
  font-size: 11px;
  cursor: pointer;
  font-family: inherit;
}
.mode-btn.active {
  background: var(--accent);
  color: #0b1320;
  border-color: var(--accent);
  font-weight: 700;
}

.param-row {
  display: flex;
  gap: 8px;
  align-items: center;
  margin-bottom: 10px;
}

input[type="number"], input[type="text"] {
  padding: 6px 10px;
  background: var(--panel-2);
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--fg);
  font-family: "SF Mono", Menlo, Consolas, monospace;
  font-size: 14px;
  width: 80px;
}
input[type="text"] { width: 100%; }
input:focus { outline: none; border-color: var(--accent); }

.dash { color: var(--muted); }

.field-explain {
  font-size: 13px;
  color: var(--accent-2);
  padding-top: 8px;
  border-top: 1px dashed var(--border);
}

.output-section {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 10px;
  overflow: hidden;
  margin-bottom: 20px;
}

.output-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 10px 18px;
  background: var(--panel-2);
  border-bottom: 1px solid var(--border);
}
.output-header > span {
  color: var(--muted);
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-weight: 600;
}

#copy-btn {
  padding: 4px 12px;
  background: var(--accent);
  color: #0b1320;
  border: none;
  border-radius: 4px;
  font-size: 11px;
  font-weight: 700;
  cursor: pointer;
  font-family: inherit;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

#output {
  margin: 0;
  padding: 20px 28px;
  font-family: "SF Mono", Menlo, Consolas, monospace;
  font-size: 28px;
  color: var(--accent);
  text-align: center;
}

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

.sibling {
  text-align: center;
}
.sibling a {
  color: var(--accent);
  text-decoration: none;
  font-size: 13px;
  padding: 8px 16px;
  border: 1px solid var(--accent);
  border-radius: 999px;
  display: inline-block;
}
.sibling a:hover {
  background: rgba(124, 196, 255, 0.1);
}

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