:root {
  --bg: #0b0d14;
  --panel: #141824;
  --text: #e6e8f0;
  --muted: #8b93a7;
  --accent: #5b6cf0;
  --border: #232838;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  line-height: 1.6;
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px 40px;
  border-bottom: 1px solid var(--border);
}

.brand {
  font-weight: 600;
  letter-spacing: .3px;
  color: var(--text);
  text-decoration: none;
}

.nav nav a {
  color: var(--muted);
  text-decoration: none;
  margin-left: 24px;
  font-size: 14px;
}

.nav nav a:hover { color: var(--text); }

main { max-width: 960px; margin: 0 auto; padding: 0 24px; }

.hero { padding: 96px 0 64px; text-align: center; }

.hero h1 {
  font-size: clamp(32px, 5vw, 52px);
  line-height: 1.25;
  margin: 0 0 24px;
}

.lead {
  color: var(--muted);
  max-width: 620px;
  margin: 0 auto 32px;
  font-size: 17px;
}

.cta {
  display: inline-block;
  background: var(--accent);
  color: #fff;
  text-decoration: none;
  padding: 12px 28px;
  border-radius: 8px;
  font-weight: 600;
}

.cta-row { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; }

.cta-secondary {
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text);
}

.cta-disabled {
  background: var(--panel);
  border: 1px dashed var(--border);
  color: var(--muted);
  cursor: not-allowed;
}

.note { color: var(--muted); font-size: 13px; margin-top: 14px; }
.note a { color: var(--accent); }

.boundary { padding: 48px 0; }
.boundary h2 { text-align: center; margin-bottom: 28px; font-size: 22px; }
.boundary-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; }
.boundary-grid > div {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 24px;
}
.boundary-grid h3 { margin: 0 0 12px; font-size: 15px; }
.boundary-grid ul { margin: 0; padding-left: 18px; color: var(--muted); font-size: 14px; }
.boundary-grid li { margin-bottom: 8px; }

.download-lead { color: var(--muted); margin-bottom: 20px; }

.install-steps {
  max-width: 620px;
  margin: 40px auto 0;
  text-align: left;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 24px 28px;
}

.install-steps h3 { margin: 0 0 12px; font-size: 15px; }
.install-steps ol { margin: 0; padding-left: 20px; color: var(--muted); font-size: 14px; }
.install-steps li { margin-bottom: 8px; }

code {
  background: #1b2030;
  border-radius: 4px;
  padding: 1px 6px;
  font-size: 13px;
  font-family: "Cascadia Code", Consolas, monospace;
}

.note.warn {
  max-width: 620px;
  margin: 20px auto 0;
  background: rgba(240, 160, 90, .08);
  border: 1px solid rgba(240, 160, 90, .25);
  border-radius: 8px;
  padding: 12px 16px;
  text-align: left;
  color: #e0b07a;
}

@media (max-width: 640px) {
  .boundary-grid { grid-template-columns: 1fr; }
}

.features {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 20px;
  padding: 32px 0 48px;
}

.features article {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 24px;
}

.features h2 { font-size: 17px; margin: 0 0 8px; }
.features p { color: var(--muted); margin: 0; font-size: 14px; }

.download { padding: 48px 0 96px; text-align: center; }
.download h2 { margin-bottom: 20px; }

footer {
  border-top: 1px solid var(--border);
  padding: 24px 40px;
  color: var(--muted);
  font-size: 13px;
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 8px;
}

.icp {
  color: var(--text);
  text-decoration: none;
  font-size: 14px;
}

.icp:hover { color: var(--accent); text-decoration: underline; }

/* ── 界面预览 ── */
.screens { padding: 48px 0; }
.screens h2 { text-align: center; margin-bottom: 32px; font-size: 22px; }

.screens figure {
  margin: 0 0 40px;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  overflow: hidden;
}

.screens img {
  display: block;
  width: 100%;
  height: auto;
  border-bottom: 1px solid var(--border);
}

.screens figcaption {
  padding: 16px 20px;
  color: var(--muted);
  font-size: 14px;
}

.screens figcaption strong { color: var(--text); }

.boundary-note {
  text-align: center;
  color: var(--muted);
  font-size: 14px;
  margin-top: 24px;
}

/* ── 三步开始 ── */
.howto { padding: 48px 0; }
.howto h2 { text-align: center; margin-bottom: 28px; font-size: 22px; }

.howto ol {
  list-style: none;
  counter-reset: step;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 20px;
}

.howto li {
  counter-increment: step;
  position: relative;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 24px 24px 24px 64px;
}

.howto li::before {
  content: counter(step);
  position: absolute;
  left: 24px;
  top: 24px;
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: var(--accent);
  color: #fff;
  font-size: 13px;
  font-weight: 600;
  display: flex;
  align-items: center;
  justify-content: center;
}

.howto strong { display: block; margin-bottom: 8px; font-size: 15px; }
.howto span { color: var(--muted); font-size: 14px; }

/* ── 常见问题 ── */
.faq { padding: 48px 0; }
.faq h2 { text-align: center; margin-bottom: 28px; font-size: 22px; }

.faq details {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 10px;
  margin-bottom: 12px;
  padding: 0 20px;
}

.faq summary {
  cursor: pointer;
  padding: 16px 0;
  font-size: 15px;
  font-weight: 500;
  list-style: none;
}

.faq summary::-webkit-details-marker { display: none; }

.faq summary::after {
  content: "+";
  float: right;
  color: var(--muted);
  font-size: 18px;
  line-height: 1;
}

.faq details[open] summary::after { content: "−"; }

.faq p {
  margin: 0 0 16px;
  color: var(--muted);
  font-size: 14px;
}

.faq a { color: var(--accent); }

@media (max-width: 640px) {
  .nav { padding: 16px 20px; flex-wrap: wrap; gap: 12px; }
  .nav nav a { margin-left: 0; margin-right: 16px; }
  main { padding: 0 16px; }
  .hero { padding: 56px 0 40px; }
}