:root {
  --bg: #f7f8fb;
  --card: #ffffff;
  --ink: #152033;
  --muted: #5b6577;
  --line: #e5e9f0;
  --brand: #2563eb;
  --brand-ink: #ffffff;
  --good: #0f766e;
  --warn-bg: #fff7ed;
  --ok-bg: #ecfdf5;
  --radius: 14px;
  --shadow: 0 10px 30px rgba(21, 32, 51, 0.08);
  --max: 920px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: "PingFang SC", "Noto Sans SC", "Microsoft YaHei", system-ui, sans-serif;
  color: var(--ink);
  background: linear-gradient(180deg, #eef3ff 0%, var(--bg) 220px);
  line-height: 1.6;
}
a { color: var(--brand); text-decoration: none; }
img, button, input, textarea { max-width: 100%; }
.wrap { width: min(100% - 2rem, var(--max)); margin-inline: auto; }

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 1rem 0;
}
.logo {
  font-weight: 700;
  font-size: 1.05rem;
  color: var(--ink);
}
.nav-links {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
  font-size: 0.95rem;
}
.nav-links a { color: var(--muted); }
.nav-links a:hover { color: var(--ink); }

.hero {
  padding: 1.5rem 0 2rem;
}
.hero-card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: calc(var(--radius) + 4px);
  box-shadow: var(--shadow);
  padding: 1.5rem;
}
.hero h1 {
  margin: 0 0 0.75rem;
  font-size: clamp(1.6rem, 5vw, 2.4rem);
  line-height: 1.25;
  letter-spacing: -0.02em;
}
.hero .lead {
  margin: 0 0 1rem;
  color: var(--muted);
  font-size: 1.05rem;
}
.trust {
  margin: 0.9rem 0 0;
  color: var(--muted);
  font-size: 0.92rem;
}

.cta {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.35rem;
  background: var(--brand);
  color: var(--brand-ink) !important;
  border: 0;
  border-radius: 999px;
  padding: 0.85rem 1.25rem;
  font-size: 1rem;
  font-weight: 650;
  cursor: pointer;
  text-decoration: none;
  box-shadow: 0 8px 18px rgba(37, 99, 235, 0.28);
}
.cta:hover { filter: brightness(1.05); }
.cta:active { transform: translateY(1px); }
.cta.secondary {
  background: #111827;
  box-shadow: none;
}
.cta-row { display: flex; flex-wrap: wrap; gap: 0.75rem; align-items: center; }

.section {
  padding: 1.75rem 0;
}
.section h2 {
  margin: 0 0 1rem;
  font-size: 1.35rem;
}
.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.9rem;
}
.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0.9rem;
}
.card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 1rem 1.1rem;
}
.card h3 {
  margin: 0 0 0.4rem;
  font-size: 1.05rem;
}
.card p, .card li { color: var(--muted); margin: 0; }
.step-num {
  display: inline-flex;
  width: 1.6rem;
  height: 1.6rem;
  border-radius: 999px;
  align-items: center;
  justify-content: center;
  background: #dbeafe;
  color: #1d4ed8;
  font-size: 0.85rem;
  font-weight: 700;
  margin-bottom: 0.55rem;
}

.demo-panel {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
}
.demo label {
  display: block;
  font-weight: 600;
  margin-bottom: 0.45rem;
}
.demo textarea {
  width: 100%;
  min-height: 110px;
  resize: vertical;
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 0.85rem 0.95rem;
  font: inherit;
  color: var(--ink);
  background: #fbfcfe;
}
.demo-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  margin-top: 0.75rem;
}
.result {
  background: #0b1220;
  color: #e8eefc;
  border-radius: 12px;
  padding: 1rem;
  min-height: 220px;
  white-space: pre-wrap;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.9rem;
  line-height: 1.55;
}
.result.empty {
  color: #93a0b8;
  font-family: inherit;
}
.result-toolbar {
  display: flex;
  justify-content: space-between;
  gap: 0.5rem;
  align-items: center;
  margin-bottom: 0.55rem;
}
.hint { color: var(--muted); font-size: 0.9rem; margin: 0.55rem 0 0; }
.copy-status { color: var(--good); font-size: 0.9rem; min-height: 1.2em; }

.contrast .bad { background: var(--warn-bg); }
.contrast .good { background: var(--ok-bg); }
.chips {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}
.chip {
  background: #eef2ff;
  color: #3730a3;
  border-radius: 999px;
  padding: 0.45rem 0.85rem;
  font-size: 0.92rem;
}

.faq details {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 0.85rem 1rem;
  margin-bottom: 0.65rem;
}
.faq summary {
  cursor: pointer;
  font-weight: 650;
}
.faq p { margin: 0.55rem 0 0; color: var(--muted); }

.cta-band {
  text-align: center;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: calc(var(--radius) + 4px);
  padding: 1.5rem 1rem;
  box-shadow: var(--shadow);
}
.cta-band p { color: var(--muted); margin: 0 0 1rem; }

.footer {
  padding: 2rem 0 2.5rem;
  color: var(--muted);
  font-size: 0.92rem;
  border-top: 1px solid var(--line);
  margin-top: 1rem;
}
.footer strong { color: var(--ink); }
.footer .links { margin-top: 0.6rem; display: flex; flex-wrap: wrap; gap: 0.85rem; }

@media (max-width: 760px) {
  .grid-3, .grid-2, .demo-panel { grid-template-columns: 1fr; }
  .hero-card, .card, .cta-band { padding: 1.1rem; }
  .nav { align-items: flex-start; }
}