:root{
  --bg: #0b0f19;
  --card: #121a2b;
  --text: #e8ecff;
  --muted: #b9c2ff;
  --accent: #7aa2ff;
  --border: rgba(255,255,255,0.08);
}

*{ box-sizing:border-box; margin:0; padding:0; }
body{
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
}

.header{
  text-align:center;
  padding: 28px 16px;
  border-bottom: 1px solid var(--border);
}
.header h1{ font-size: 2.2rem; }
.header p{ color: var(--muted); }

.nav{
  display:flex;
  gap:12px;
  justify-content:center;
  padding: 10px;
  flex-wrap:wrap;
  border-bottom: 1px solid var(--border);
}
.nav a{
  color: var(--accent);
  text-decoration:none;
  padding: 8px 12px;
  border: 1px solid var(--border);
  border-radius: 12px;
}
.nav a:hover{
  background: rgba(122,162,255,0.12);
}

.container{
  max-width: 1050px;
  margin: 0 auto;
  padding: 20px 14px 70px;
}

.hero{
  display:grid;
  grid-template-columns: 1.2fr 1fr;
  gap: 18px;
  align-items:center;
  margin-top: 12px;
  padding: 16px;
  border: 1px solid var(--border);
  border-radius: 18px;
  background: linear-gradient(180deg, rgba(122,162,255,0.08), rgba(18,26,43,0.0));
}

.tip{
  margin-top:10px;
  color: var(--muted);
}

.imgCard img{
  width:100%;
  border-radius: 18px;
  border: 1px solid var(--border);
}
.imgCard figcaption{
  margin-top: 8px;
  color: var(--muted);
  font-size: 0.9rem;
}

.section{
  margin-top: 26px;
}
.section h2{
  font-size: 1.5rem;
  margin-bottom: 12px;
}

.card{
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 16px;
  margin-bottom: 14px;
  box-shadow: 0 8px 22px rgba(0,0,0,0.25);
}

.card h3{
  font-size: 1.2rem;
  margin-bottom: 6px;
  color: #dbe2ff;
}

.grid2{
  display:grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin-top: 10px;
}

.diagram img{
  width:100%;
  border-radius: 16px;
  border: 1px solid var(--border);
  background: white;
}

pre{
  background: rgba(0,0,0,0.35);
  border: 1px solid var(--border);
  padding: 12px;
  border-radius: 16px;
  overflow:auto;
  margin-top: 10px;
  font-size: 0.95rem;
}
code{ color: #e7f0ff; }

.note{
  color: var(--muted);
  margin-top: 10px;
}

.footer{
  margin-top: 30px;
  text-align:center;
  color: var(--muted);
  padding: 24px 10px 0;
  border-top: 1px solid var(--border);
}

@media(max-width: 850px){
  .hero{ grid-template-columns: 1fr; }
  .grid2{ grid-template-columns: 1fr; }
}