:root {
  --bg: #0f1419;
  --surface: #1a2332;
  --border: #2d3a4d;
  --text: #e8edf4;
  --muted: #8b9cb3;
  --accent: #3d9cf5;
  --accent-dim: #2563a8;
  --success: #34d399;
  --err: #f87171;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  min-height: 100vh;
  font-family: "SF Pro SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.55;
}
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
.wrap {
  max-width: 960px;
  margin: 0 auto;
  padding: 1.5rem 1rem 3rem;
}
header {
  margin-bottom: 2rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--border);
}
header h1 {
  margin: 0 0 0.35rem;
  font-size: 1.35rem;
  font-weight: 600;
}
header p { margin: 0; color: var(--muted); font-size: 0.9rem; }
.nav-tools {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: 1rem;
}
.nav-tools a {
  padding: 0.35rem 0.75rem;
  border-radius: 6px;
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--text);
  text-decoration: none;
  font-size: 0.875rem;
}
.nav-tools a:hover {
  border-color: var(--accent);
  color: var(--accent);
}
.nav-tools a.active {
  border-color: var(--accent);
  background: rgba(61, 156, 245, 0.15);
  color: var(--accent);
}
select, input[type="number"] {
  padding: 0.45rem 0.65rem;
  border-radius: 6px;
  border: 1px solid var(--border);
  background: #121820;
  color: var(--text);
  font-family: inherit;
  font-size: 0.875rem;
}
select:focus, input[type="number"]:focus {
  outline: none;
  border-color: var(--accent);
}
.mono-out {
  font-family: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  font-size: 0.8125rem;
  word-break: break-all;
}
.section-title {
  font-size: 0.95rem;
  font-weight: 600;
  margin: 1.25rem 0 0.75rem;
  color: var(--text);
}
fieldset.group {
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0.75rem 1rem 1rem;
  margin: 0 0 1rem;
}
fieldset.group legend {
  padding: 0 0.35rem;
  font-size: 0.8125rem;
  color: var(--muted);
}
.checkbox-row label {
  display: inline;
  margin-right: 1rem;
  cursor: pointer;
}
.checkbox-row input { margin-right: 0.25rem; vertical-align: middle; }
.cards {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 1rem;
}
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 1.25rem;
  transition: border-color 0.15s;
}
.card:hover { border-color: var(--accent-dim); }
.card h2 {
  margin: 0 0 0.5rem;
  font-size: 1.05rem;
}
.card p {
  margin: 0 0 1rem;
  color: var(--muted);
  font-size: 0.875rem;
}
.btn {
  display: inline-block;
  padding: 0.45rem 1rem;
  border-radius: 6px;
  border: none;
  background: var(--accent);
  color: #fff;
  font-size: 0.875rem;
  cursor: pointer;
  font-family: inherit;
}
.btn:hover { filter: brightness(1.08); }
.btn.secondary {
  background: var(--surface);
  color: var(--text);
  border: 1px solid var(--border);
}
.btn.secondary:hover { border-color: var(--accent); }
label {
  display: block;
  margin-bottom: 0.35rem;
  font-size: 0.875rem;
  color: var(--muted);
}
textarea, input[type="text"] {
  width: 100%;
  padding: 0.65rem 0.75rem;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: #121820;
  color: var(--text);
  font-family: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  font-size: 0.8125rem;
  resize: vertical;
}
textarea:focus, input:focus {
  outline: none;
  border-color: var(--accent);
}
.field { margin-bottom: 1rem; }
.row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  align-items: center;
  margin-bottom: 1rem;
}
.hint {
  font-size: 0.8125rem;
  color: var(--muted);
  margin: 0.5rem 0 0;
}
.err {
  color: var(--err);
  font-size: 0.875rem;
  white-space: pre-wrap;
  margin: 0.5rem 0 0;
}
.ok { color: var(--success); font-size: 0.875rem; margin: 0.5rem 0 0; }
footer {
  margin-top: 2.5rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border);
  font-size: 0.8125rem;
  color: var(--muted);
}