/* Base */
* { box-sizing: border-box; margin: 0; padding: 0; }
:root{
  --bg: #0a0e27;
  --panel: rgba(30,41,59,.55);
  --panel-strong: rgba(30,41,59,.85);
  --text: #e4e4e7;
  --muted: #94a3b8;
  --line: rgba(255,255,255,.1);
  --primary: #60a5fa;
  --secondary: #a78bfa;
  --radius: 14px;
}
html,body{height:100%}
body{
  font-family: 'Inter', system-ui, -apple-system, Segoe UI, Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
}

/* Header / Nav */
.site-header{
  position: sticky; top: 0; z-index: 1000;
  background: rgba(15,23,42,.96);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(10px);
}
.nav{
  max-width: 1200px; margin: 0 auto; padding: .9rem 1rem;
  display:flex; align-items:center; justify-content:space-between; gap:1rem;
}
.logo{ display:flex; align-items:center; gap:.6rem; color:var(--primary); text-decoration:none; font-weight:800; }
.logo-icon{
  width:40px; height:40px; border-radius:10px;
  display:grid; place-items:center; background: linear-gradient(135deg, #ffffff, #ffffff);
}
.nav-links{ list-style:none; display:flex; gap:1.25rem; }
.nav-links a{
  color:#cbd5e1; text-decoration:none; font-weight:600; padding:.5rem 0; position:relative; transition:.25s;
}
.nav-links a:hover{ color:var(--primary); }
.nav-links a.active{ color:var(--primary); }
.nav-links a.active::after, .nav-links a:hover::after{
  content:""; position:absolute; left:0; bottom:-6px; height:2px; width:100%; background:var(--primary);
}

/* Mobile menu */
.menu-toggle{ display:none; background:transparent; border:0; cursor:pointer; }
.menu-toggle span{ display:block; width:24px; height:3px; background:#cbd5e1; margin:5px 0; transition:.3s; border-radius:3px; }

/* Hero */
.hero{ max-width: 1200px; margin: 0 auto; padding: 4rem 1rem; text-align:center; }
.hero h1{
  font-size: clamp(2rem, 6vw, 3.6rem);
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  -webkit-background-clip:text; background-clip:text; color:transparent; margin-bottom:.6rem;
}
.subtitle{ color: var(--text); font-weight:700; }
.description{ color: #64748b; max-width: 700px; margin:.6rem auto 1.4rem; }

.search-container{ max-width:640px; margin:1.2rem auto 0; position:relative; }
.search-container input{
  width:100%; padding:1rem 1rem 1rem 3.2rem; border-radius:12px; border:1px solid var(--line);
  background: var(--panel); color: var(--text);
}
.search-container input:focus{ outline:none; border-color: var(--primary); background: var(--panel-strong); }
.search-icon{ position:absolute; left:1rem; top:50%; transform:translateY(-50%); color:#64748b; }

.cta-button{
  margin-top:1.2rem; display:inline-flex; align-items:center; gap:.5rem;
  padding: .9rem 1.4rem; border-radius:12px; border:0; cursor:pointer; text-decoration:none; color:#fff;
  background: linear-gradient(135deg, #3b82f6, #8b5cf6); font-weight:700; transition:.25s;
}
.cta-button:hover{ transform: translateY(-2px); box-shadow: 0 10px 30px rgba(59,130,246,.4); }

/* Container & sections */
.container{ max-width:1200px; margin:0 auto; padding:2rem 1rem; }
.section-title{
  font-size: clamp(1.8rem, 4vw, 2.4rem); font-weight:800;
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  -webkit-background-clip:text; background-clip:text; color:transparent;
}
.section-subtitle{ color: var(--muted); margin-bottom:1.4rem; }

.topics-grid{
  display:grid; grid-template-columns: repeat(auto-fit,minmax(260px,1fr)); gap:1rem; margin-top:.6rem;
}
.topic-card{
  display:block; padding:1.6rem; border-radius:16px; border:1px solid var(--line);
  background: var(--panel); transition:.25s; text-decoration:none; color:var(--text); position:relative; overflow:hidden;
}
.topic-card:hover{ transform: translateY(-6px); border-color: rgba(96,165,250,.55); background: var(--panel-strong); }
.topic-card::before{
  content:""; position:absolute; inset:auto 0 0 0; height:4px; background: linear-gradient(90deg,#3b82f6,#8b5cf6);
  transform: scaleX(0); transform-origin:left; transition:.25s;
}
.topic-card:hover::before{ transform: scaleX(1); }
.topic-icon{ font-size:2rem; color:var(--primary); margin-bottom:.7rem; }
.topic-card h3{ font-size:1.3rem; margin-bottom:.4rem; }
.topic-card p{ color: var(--muted); }
.topic-badge{
  display:inline-flex; align-items:center; gap:.4rem; margin-top:1rem;
  font-size:.85rem; color: var(--primary); background: rgba(59,130,246,.15);
  padding:.35rem .8rem; border-radius:999px; font-weight:700;
}

/* Content pages */
.content-header{
  max-width:1200px; margin: 1.5rem auto 0; padding:2rem 1rem; text-align:center;
  background: var(--panel); border:1px solid var(--line); border-radius:16px;
}
.content-header h1{ font-size: clamp(1.8rem,4vw,2.6rem); }
.muted{ color: var(--muted); }

.content-section{
  background: var(--panel); border:1px solid var(--line); border-radius:16px;
  padding:1.4rem; margin-bottom:1.2rem;
}
.content-section h2{ color: var(--primary); display:flex; align-items:center; gap:.6rem; }
.content-section h3{ margin:1rem 0 .5rem; }
.content-section ul{ margin-left:1.2rem; }
.content-section li{ margin:.5rem 0; }

.code-block{
  background:#0f172a; border:1px solid var(--line); border-radius:10px;
  padding:1rem; overflow:auto; color:#cbd5e1; font-family: ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace; font-size:.95rem;
}
.info-box{
  background: rgba(59,130,246,.12); border-left:4px solid #3b82f6;
  border-radius:10px; padding:1rem; margin-top:1rem;
}

/* Footer */
.footer{
  margin-top:2rem; padding:2rem 1rem; text-align:center; background: rgba(15,23,42,.96); border-top:1px solid var(--line);
}
.footer-brand{
  font-size:1.4rem; font-weight:800;
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  -webkit-background-clip:text; background-clip:text; color:transparent; margin-bottom:.5rem;
}
.social-links{ display:flex; gap:1rem; justify-content:center; margin-top:1rem; }
.social-links a{ color:#94a3b8; font-size:1.3rem; transition:.25s; }
.social-links a:hover{ color: var(--primary); transform: translateY(-3px); }

/* Responsive nav */
@media (max-width: 860px){
  .menu-toggle{ display:block; }
  .nav-links{ position: fixed; inset: 64px 0 auto 0; background: rgba(15,23,42,.98);
    transform: translateY(-149%); transition: transform .3s; flex-direction: column; gap:1.2rem; padding:1rem 1.2rem; border-bottom:1px solid var(--line);
  }
  .nav-links.open{ transform: translateY(0); }
}