:root{
  --bg-primary:#0a0a0f;
  --bg-secondary:#12121a;
  --bg-card:#16161f;
  --text-primary:#f0f0f5;
  --text-secondary:#a0a0b0;
  --accent-primary:#6366f1;
  --accent-secondary:#818cf8;
  --success:#10b981;
  --warning:#f59e0b;
  --border:#2a2a3a;
}
*{box-sizing:border-box}
body{
  margin:0;
  font-family:"Outfit",sans-serif;
  color:var(--text-primary);
  background:radial-gradient(1200px 600px at 10% -10%, #1a1a2b 0%, transparent 50%), var(--bg-primary);
  height:100vh;
  overflow:hidden;
}
a{color:inherit;text-decoration:none}
.app{
  display:flex;
  height:100vh;
  width:100%;
}
.sidebar{
  width:280px;
  background:var(--bg-secondary);
  border-right:1px solid var(--border);
  padding:24px 18px;
  position:fixed;
  left:0;top:0;bottom:0;
  overflow:auto;
  transition:transform .3s ease;
  z-index:20;
}
.brand{
  font-size:20px;
  font-weight:700;
  letter-spacing:.3px;
  margin-bottom:16px;
}
.subtitle{
  color:var(--text-secondary);
  font-size:13px;
  margin-bottom:18px;
}
.nav{
  display:flex;
  flex-direction:column;
  gap:6px;
}
.nav a{
  padding:10px 12px;
  border-radius:10px;
  color:var(--text-secondary);
  border:1px solid transparent;
  transition:.2s ease;
}
.nav a:hover{
  color:var(--text-primary);
  background:rgba(99,102,241,.08);
  border-color:rgba(99,102,241,.25);
}
.nav a.active{
  color:var(--text-primary);
  background:rgba(99,102,241,.18);
  border-color:rgba(99,102,241,.4);
}
.progress-wrap{
  margin-top:18px;
  background:var(--bg-card);
  border:1px solid var(--border);
  border-radius:999px;
  height:10px;
  overflow:hidden;
}
.progress-bar{
  height:100%;
  width:0%;
  background:linear-gradient(90deg, var(--accent-primary), var(--accent-secondary));
  transition:width .3s ease;
}
.main{
  margin-left:280px;
  flex:1;
  padding:26px 34px;
  height:100vh;
  overflow:auto;
}
.topbar{
  display:flex;
  align-items:center;
  justify-content:space-between;
  margin-bottom:18px;
}
.mobile-menu-btn{
  display:none;
  background:var(--bg-card);
  border:1px solid var(--border);
  color:var(--text-primary);
  padding:8px 12px;
  border-radius:10px;
  font-size:18px;
  cursor:pointer;
}
.section{animation:fade .35s ease}
@keyframes fade{from{opacity:.2;transform:translateY(6px)}to{opacity:1;transform:translateY(0)}}
h1{font-size:32px;margin:6px 0 10px}
h2{font-size:22px;margin:22px 0 8px}
h3{font-size:18px;margin:18px 0 8px}
p{color:var(--text-secondary);line-height:1.6}
.lead{font-size:17px;color:var(--text-primary)}
.cards-grid{
  display:grid;
  grid-template-columns:repeat(auto-fit,minmax(210px,1fr));
  gap:14px;
  margin:14px 0 4px;
}
.card{
  background:var(--bg-card);
  border:1px solid var(--border);
  border-radius:14px;
  padding:14px;
}
.card-icon{font-size:22px;margin-bottom:8px}
.theme-card{
  border:1px solid var(--border);
  background:linear-gradient(135deg, rgba(99,102,241,.18), rgba(129,140,248,.12));
  border-radius:14px;
  padding:16px;
  display:flex;
  flex-direction:column;
  gap:8px;
}
.theme-card button{
  align-self:flex-start;
  background:var(--accent-primary);
  color:#0a0a0f;
  border:none;
  padding:8px 12px;
  border-radius:10px;
  font-weight:600;
  cursor:pointer;
}
.back-home{
  display:inline-flex;
  align-items:center;
  gap:8px;
  background:var(--bg-card);
  border:1px solid var(--border);
  color:var(--text-primary);
  padding:8px 12px;
  border-radius:10px;
  cursor:pointer;
  margin-bottom:12px;
}
.back-home img{
  width:180px;
  height:180px;
  object-fit:contain;
}
.info-box{
  border:1px solid var(--border);
  background:var(--bg-card);
  border-radius:12px;
  padding:12px 14px;
  margin:12px 0;
}
.info-box.tip{border-color:rgba(16,185,129,.35)}
.info-box.warning{border-color:rgba(245,158,11,.35)}
.info-box.important{border-color:rgba(99,102,241,.35)}
.diagram{
  background:var(--bg-card);
  border:1px solid var(--border);
  border-radius:10px;
  padding:12px;
  font-family:"JetBrains Mono",monospace;
  white-space:pre;
  overflow:auto;
  color:#d9d9e7;
}
.step{
  display:flex;
  gap:12px;
  background:var(--bg-card);
  border:1px solid var(--border);
  border-radius:12px;
  padding:12px 14px;
  margin:10px 0;
}
.step-number{
  width:28px;height:28px;
  display:flex;align-items:center;justify-content:center;
  background:rgba(99,102,241,.2);
  border:1px solid rgba(99,102,241,.45);
  border-radius:8px;
  font-weight:700;
}
pre{
  background:#0f0f18;
  border:1px solid var(--border);
  border-radius:12px;
  padding:12px;
  overflow:auto;
  font-family:"JetBrains Mono",monospace;
  font-size:13px;
  line-height:1.5;
  color:#d7d7e6;
}
code{font-family:"JetBrains Mono",monospace}
.keyword{color:#c792ea}
.string{color:#c3e88d}
.comment{color:#546e7a}
.annotation{color:#ffcb6b}
.class-name{color:#82aaff}
.number{color:#f78c6c}
table{
  width:100%;
  border-collapse:collapse;
  margin:10px 0 6px;
  background:var(--bg-card);
  border:1px solid var(--border);
  border-radius:12px;
  overflow:hidden;
}
th,td{
  padding:10px 12px;
  border-bottom:1px solid var(--border);
  text-align:left;
  color:var(--text-secondary);
}
th{color:var(--text-primary);background:#14141f}
ul{color:var(--text-secondary);line-height:1.6}
.footer-nav{
  display:flex;
  justify-content:space-between;
  margin-top:22px;
  gap:10px;
}
.footer-nav-btn{
  flex:1;
  text-align:center;
  padding:10px 12px;
  border-radius:10px;
  background:var(--bg-card);
  border:1px solid var(--border);
  cursor:pointer;
  color:var(--text-primary);
  transition:.2s ease;
}
.footer-nav-btn:hover{
  border-color:rgba(99,102,241,.5);
  background:rgba(99,102,241,.12);
}
.footer-nav-btn.next{
  background:linear-gradient(90deg, rgba(99,102,241,.2), rgba(129,140,248,.2));
  border-color:rgba(99,102,241,.5);
}
.media{margin:10px 0 4px}
.media img{
  width:100%;
  display:block;
  border-radius:12px;
  border:1px solid var(--border);
  background:#0e0e16;
  cursor:zoom-in;
  max-height:420px;
  object-fit:contain;
}
.media figcaption{
  margin-top:8px;
  font-size:12px;
  color:var(--text-secondary);
}
.lightbox{
  position:fixed;
  inset:0;
  background:rgba(5,5,10,.85);
  display:none;
  align-items:center;
  justify-content:center;
  z-index:50;
  padding:20px;
}
.lightbox.open{display:flex}
.lightbox-content{
  max-width:92vw;
  max-height:90vh;
  background:#0e0e16;
  border:1px solid var(--border);
  border-radius:14px;
  padding:12px;
  display:flex;
  flex-direction:column;
  gap:8px;
}
.lightbox-content img{
  max-width:88vw;
  max-height:78vh;
  object-fit:contain;
  border-radius:10px;
}
.lightbox-caption{
  font-size:12px;
  color:var(--text-secondary);
  text-align:center;
}
.mobile-overlay{
  display:none;
  position:fixed;
  inset:0;
  background:rgba(0,0,0,.5);
  z-index:15;
}
@media (max-width:1024px){
  .sidebar{transform:translateX(-100%)}
  .sidebar.open{transform:translateX(0)}
  .main{margin-left:0}
  .mobile-menu-btn{display:inline-flex}
  .mobile-overlay.open{display:block}
}