:root {
  --ink: #0f172a;
  --muted: #64748b;
  --line: #e2e8f0;
  --bg: #f7f8fa;
  --brand: #1e3a5f;
  --accent: #2563eb;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, sans-serif;
  -webkit-font-smoothing: antialiased;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 20px;
  background: var(--brand);
  color: #fff;
  position: sticky;
  top: 0;
  z-index: 10;
}

.brand { font-size: 16px; font-weight: 700; letter-spacing: .5px; }
.who { font-size: 13px; opacity: .85; }

.page {
  max-width: 720px;
  margin: 0 auto;
  padding: 28px 20px 40px;
}

h1 {
  margin: 8px 0 8px;
  font-size: 24px;
  font-weight: 700;
}

.lead {
  margin: 0 0 22px;
  color: var(--muted);
  font-size: 14px;
  line-height: 1.7;
}

.cards {
  display: grid;
  gap: 12px;
}

@media (min-width: 560px) {
  .cards { grid-template-columns: 1fr 1fr; }
  .cards .card:first-child { grid-column: span 2; }
}

.card {
  display: flex;
  flex-direction: column;
  gap: 6px;
  text-align: left;
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: #fff;
  cursor: pointer;
  font: inherit;
  color: inherit;
  transition: border-color .15s, transform .15s;
}

.card:hover { border-color: var(--accent); transform: translateY(-1px); }
.card:active { transform: translateY(0); }

.card strong { font-size: 16px; }
.card span { font-size: 13px; color: var(--muted); }

.result {
  margin-top: 24px;
  padding: 18px;
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 12px;
}

.result h2 { margin: 0 0 10px; font-size: 15px; }

.result pre {
  margin: 0;
  font-size: 13px;
  line-height: 1.7;
  white-space: pre-wrap;
  word-break: break-all;
  color: #334155;
}

.foot {
  padding: 18px 20px 28px;
  text-align: center;
  font-size: 12px;
  color: #94a3b8;
}