/* ===== CSS Variables ===== */
:root {
  --bg-primary: #0d1117;
  --bg-secondary: #161b22;
  --bg-card: #1c2128;
  --border: #30363d;
  --border-light: #21262d;
  --text-primary: #e6edf3;
  --text-secondary: #8b949e;
  --text-muted: #6e7681;
  --accent: #f97316;
  --accent-hover: #ea6c0a;
  --accent-glow: rgba(249, 115, 22, 0.15);
  --green: #3fb950;
  --blue: #58a6ff;
  --radius: 12px;
  --radius-sm: 8px;
  --shadow: 0 4px 24px rgba(0, 0, 0, 0.4);
  --nav-height: 64px;
}

/* ===== Reset ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; font-size: 16px; }
body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
}
a { color: var(--accent); text-decoration: none; transition: color 0.2s; }
a:hover { color: var(--accent-hover); }
img { max-width: 100%; height: auto; display: block; }
ul, ol { list-style: none; }

/* ===== Navigation ===== */
.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--nav-height);
  background: rgba(13, 17, 23, 0.92);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-light);
  display: flex;
  align-items: center;
}
.nav-inner {
  width: 100%;
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.nav-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--text-primary);
}
.nav-logo .logo-icon {
  width: 32px;
  height: 32px;
  background: linear-gradient(135deg, var(--accent), #fb923c);
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 16px;
}
.nav-links {
  display: flex;
  align-items: center;
  gap: 8px;
}
.nav-links a {
  color: var(--text-secondary);
  font-size: 0.9rem;
  padding: 6px 14px;
  border-radius: 6px;
  transition: all 0.2s;
}
.nav-links a:hover, .nav-links a.active {
  color: var(--text-primary);
  background: var(--bg-card);
}
.nav-links a.active { color: var(--accent); }
.nav-btn {
  background: var(--accent);
  color: #fff !important;
  padding: 8px 18px !important;
  border-radius: 8px !important;
  font-weight: 600;
}
.nav-btn:hover { background: var(--accent-hover) !important; color: #fff !important; }

/* ===== Hamburger (mobile) ===== */
.nav-toggle { display: none; background: none; border: none; cursor: pointer; padding: 4px; }
.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--text-primary);
  margin: 5px 0;
  transition: all 0.3s;
  border-radius: 2px;
}

/* ===== Layout ===== */
.container { max-width: 1100px; margin: 0 auto; padding: 0 24px; }
.section { padding: 80px 0; }
.section-sm { padding: 48px 0; }

/* ===== Hero ===== */
.hero {
  padding: 100px 0 80px;
  text-align: center;
  position: relative;
  overflow: hidden;
}
.hero::before {
  content: '';
  position: absolute;
  top: -200px;
  left: 50%;
  transform: translateX(-50%);
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(249, 115, 22, 0.08) 0%, transparent 70%);
  pointer-events: none;
}
.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 14px;
  background: var(--accent-glow);
  border: 1px solid rgba(249, 115, 22, 0.3);
  border-radius: 100px;
  font-size: 0.82rem;
  color: var(--accent);
  margin-bottom: 24px;
}
.hero h1 {
  font-size: clamp(2rem, 5vw, 3.2rem);
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 20px;
  background: linear-gradient(135deg, #e6edf3 0%, #8b949e 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero h1 .highlight {
  background: linear-gradient(135deg, var(--accent), #fb923c);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero p {
  font-size: 1.15rem;
  color: var(--text-secondary);
  max-width: 560px;
  margin: 0 auto 40px;
}
.hero-actions { display: flex; gap: 16px; justify-content: center; flex-wrap: wrap; }

/* ===== Buttons ===== */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 28px;
  border-radius: var(--radius-sm);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s;
  border: none;
  text-decoration: none;
}
.btn-primary {
  background: var(--accent);
  color: #fff;
  box-shadow: 0 4px 20px rgba(249, 115, 22, 0.3);
}
.btn-primary:hover {
  background: var(--accent-hover);
  color: #fff;
  transform: translateY(-1px);
  box-shadow: 0 6px 24px rgba(249, 115, 22, 0.4);
}
.btn-secondary {
  background: var(--bg-card);
  color: var(--text-primary);
  border: 1px solid var(--border);
}
.btn-secondary:hover {
  background: var(--bg-secondary);
  color: var(--text-primary);
  border-color: var(--text-muted);
}
.btn-lg { padding: 16px 36px; font-size: 1.1rem; }
.btn-sm { padding: 8px 18px; font-size: 0.88rem; }

/* ===== Steps Overview (homepage) ===== */
.steps-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  margin-top: 48px;
}
.step-card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius);
  padding: 32px 28px;
  position: relative;
  transition: all 0.3s;
}
.step-card:hover {
  border-color: var(--accent);
  box-shadow: 0 0 0 1px var(--accent), var(--shadow);
  transform: translateY(-2px);
}
.step-card a { color: inherit; text-decoration: none; display: block; }
.step-num {
  width: 44px;
  height: 44px;
  border-radius: 12px;
  background: var(--accent-glow);
  border: 1px solid rgba(249, 115, 22, 0.3);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.2rem;
  font-weight: 800;
  color: var(--accent);
  margin-bottom: 20px;
}
.step-card h3 { font-size: 1.1rem; margin-bottom: 10px; }
.step-card p { color: var(--text-secondary); font-size: 0.92rem; line-height: 1.6; }
.step-arrow {
  position: absolute;
  right: -12px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--border);
  font-size: 1.4rem;
  z-index: 1;
}

/* ===== Progress Indicator ===== */
.progress-bar {
  background: var(--bg-secondary);
  border-bottom: 1px solid var(--border-light);
  padding: 20px 0;
}
.progress-inner {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0;
}
.prog-step {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 0.88rem;
  color: var(--text-muted);
}
.prog-step.active { color: var(--text-primary); }
.prog-step.done { color: var(--green); }
.prog-num {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  border: 2px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 0.85rem;
  flex-shrink: 0;
}
.prog-step.active .prog-num {
  border-color: var(--accent);
  background: var(--accent);
  color: #fff;
}
.prog-step.done .prog-num {
  border-color: var(--green);
  background: var(--green);
  color: #fff;
}
.prog-line {
  width: 80px;
  height: 2px;
  background: var(--border);
  margin: 0 16px;
}
.prog-line.done { background: var(--green); }

/* ===== Page Header ===== */
.page-header {
  padding: 60px 0 40px;
  text-align: center;
}
.page-header h1 { font-size: clamp(1.6rem, 3vw, 2.4rem); font-weight: 800; margin-bottom: 12px; }
.page-header p { color: var(--text-secondary); font-size: 1.05rem; max-width: 520px; margin: 0 auto; }

/* ===== Video Container ===== */
.video-wrap {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  position: relative;
  aspect-ratio: 16/9;
  margin: 40px 0;
}
.video-wrap iframe {
  width: 100%;
  height: 100%;
  border: none;
  display: block;
}
.video-placeholder {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 16px;
  background: linear-gradient(135deg, #1c2128, #161b22);
}
.video-placeholder .play-icon {
  width: 72px;
  height: 72px;
  border-radius: 50%;
  background: var(--accent);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 28px;
  color: #fff;
  box-shadow: 0 8px 32px rgba(249, 115, 22, 0.4);
}
.video-placeholder p { color: var(--text-secondary); font-size: 0.95rem; }

/* ===== Info Cards ===== */
.info-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 20px;
  margin: 32px 0;
}
.info-card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius);
  padding: 24px;
}
.info-card h4 { display: flex; align-items: center; gap: 8px; margin-bottom: 12px; font-size: 0.95rem; }
.info-card ul li {
  color: var(--text-secondary);
  font-size: 0.9rem;
  padding: 6px 0;
  border-bottom: 1px solid var(--border-light);
  display: flex;
  align-items: flex-start;
  gap: 8px;
}
.info-card ul li:last-child { border-bottom: none; }
.info-card ul li::before { content: '•'; color: var(--accent); flex-shrink: 0; margin-top: 1px; }

/* ===== Steps List ===== */
.steps-list { margin: 32px 0; }
.step-item {
  display: flex;
  gap: 20px;
  padding: 24px 0;
  border-bottom: 1px solid var(--border-light);
}
.step-item:last-child { border-bottom: none; }
.step-item-num {
  width: 36px;
  height: 36px;
  border-radius: 10px;
  background: var(--accent-glow);
  border: 1px solid rgba(249, 115, 22, 0.3);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 0.9rem;
  color: var(--accent);
  flex-shrink: 0;
  margin-top: 2px;
}
.step-item-body h4 { margin-bottom: 6px; font-size: 1rem; }
.step-item-body p { color: var(--text-secondary); font-size: 0.92rem; }
.step-item-body code {
  display: inline-block;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 3px 10px;
  font-family: 'Cascadia Code', 'Fira Code', Consolas, monospace;
  font-size: 0.88rem;
  color: var(--blue);
  margin-top: 8px;
}

/* ===== Screenshot Placeholder ===== */
.screenshot-placeholder {
  background: var(--bg-secondary);
  border: 1px dashed var(--border);
  border-radius: var(--radius-sm);
  padding: 40px;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.88rem;
  margin: 16px 0;
}

/* ===== Alert / Tip Box ===== */
.tip-box {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-left: 3px solid var(--accent);
  border-radius: var(--radius-sm);
  padding: 16px 20px;
  margin: 20px 0;
  font-size: 0.92rem;
  color: var(--text-secondary);
}
.tip-box strong { color: var(--accent); }
.tip-box.tip-green { border-left-color: var(--green); }
.tip-box.tip-green strong { color: var(--green); }
.tip-box.tip-blue { border-left-color: var(--blue); }
.tip-box.tip-blue strong { color: var(--blue); }

/* ===== Download Card ===== */
.download-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 40px;
  text-align: center;
  margin: 40px 0;
}
.download-card .file-icon { font-size: 4rem; margin-bottom: 16px; }
.download-card h3 { font-size: 1.4rem; margin-bottom: 8px; }
.download-card p { color: var(--text-secondary); margin-bottom: 28px; }
.download-meta { display: flex; gap: 24px; justify-content: center; margin-top: 20px; flex-wrap: wrap; }
.download-meta span { color: var(--text-muted); font-size: 0.85rem; display: flex; align-items: center; gap: 4px; }

/* ===== FAQ ===== */
.faq-list { margin: 40px 0; }
.faq-item {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-sm);
  margin-bottom: 12px;
  overflow: hidden;
}
.faq-question {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 20px 24px;
  cursor: pointer;
  font-weight: 600;
  font-size: 0.97rem;
  transition: background 0.2s;
  user-select: none;
}
.faq-question:hover { background: var(--bg-secondary); }
.faq-chevron {
  color: var(--text-muted);
  transition: transform 0.3s;
  flex-shrink: 0;
  margin-left: 12px;
  font-style: normal;
}
.faq-item.open .faq-chevron { transform: rotate(180deg); }
.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.35s ease;
}
.faq-item.open .faq-answer { max-height: 600px; }
.faq-answer-inner {
  padding: 0 24px 20px;
  color: var(--text-secondary);
  font-size: 0.93rem;
  line-height: 1.7;
  border-top: 1px solid var(--border-light);
  padding-top: 16px;
}
.faq-answer-inner a { color: var(--accent); }

/* ===== Navigation Actions ===== */
.page-actions {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin: 60px 0 40px;
  padding-top: 32px;
  border-top: 1px solid var(--border-light);
}

/* ===== Features strip ===== */
.features-strip {
  display: flex;
  gap: 32px;
  justify-content: center;
  flex-wrap: wrap;
  margin-top: 60px;
  padding-top: 48px;
  border-top: 1px solid var(--border-light);
}
.feature-item {
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--text-secondary);
  font-size: 0.9rem;
}
.feature-item .icon { font-size: 1.2rem; }

/* ===== Footer ===== */
.footer {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-light);
  padding: 40px 0;
  margin-top: auto;
}
.footer-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
  text-align: center;
}
.footer-links { display: flex; gap: 24px; flex-wrap: wrap; justify-content: center; }
.footer-links a { color: var(--text-muted); font-size: 0.88rem; }
.footer-links a:hover { color: var(--text-secondary); }
.footer-disclaimer {
  color: var(--text-muted);
  font-size: 0.82rem;
  max-width: 640px;
  line-height: 1.6;
}
.footer-copy { color: var(--text-muted); font-size: 0.8rem; }

/* ===== Responsive ===== */
@media (max-width: 768px) {
  .nav-links { display: none; flex-direction: column; }
  .nav-links.open {
    display: flex;
    position: absolute;
    top: var(--nav-height);
    left: 0;
    right: 0;
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border);
    padding: 16px;
    gap: 4px;
  }
  .nav-toggle { display: flex; flex-direction: column; }

  .steps-grid { grid-template-columns: 1fr; }
  .step-arrow { display: none; }

  .hero { padding: 60px 0 40px; }
  .section { padding: 48px 0; }

  .progress-inner { gap: 0; }
  .prog-line { width: 40px; margin: 0 8px; }
  .prog-step span { display: none; }

  .page-actions { flex-direction: column; gap: 12px; }
  .page-actions .btn { width: 100%; justify-content: center; }

  .download-card { padding: 28px 20px; }
  .info-grid { grid-template-columns: 1fr; }
}

@media (max-width: 480px) {
  .container { padding: 0 16px; }
  .hero h1 { font-size: 1.8rem; }
  .hero p { font-size: 1rem; }
  .hero-actions { flex-direction: column; }
  .hero-actions .btn { width: 100%; justify-content: center; }
}