:root{
  --bg:#09101f;
  --bg-2:#101933;
  --panel:#131d3b;
  --panel-2:#1b2750;
  --text:#edf3ff;
  --muted:#b5c2e3;
  --primary:#57b5ff;
  --primary-2:#2e8fe0;
  --accent:#7af3d1;
  --border:rgba(255,255,255,.08);
  --shadow:0 18px 40px rgba(0,0,0,.30);
  --radius:20px;
  --max:1180px;
}
*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{
  font-family:Arial,Helvetica,sans-serif;
  color:var(--text);
  background:
    radial-gradient(circle at top left, rgba(87,181,255,.16), transparent 26%),
    radial-gradient(circle at top right, rgba(122,243,209,.12), transparent 22%),
    linear-gradient(180deg, #09101f 0%, #0b1430 100%);
  line-height:1.7;
}
a{text-decoration:none;color:inherit}
img{max-width:100%;display:block}
.container{width:min(92%,var(--max));margin:0 auto}
.section{padding:80px 0}
header{
  position:sticky;top:0;z-index:1000;
  background:rgba(9,16,31,.84);
  backdrop-filter:blur(12px);
  border-bottom:1px solid var(--border);
}
.navbar{
  min-height:74px;
  display:flex;align-items:center;justify-content:space-between;gap:18px;
}
.brand{
  display:flex;align-items:center;gap:12px;
  font-size:1.3rem;font-weight:800;
}
.brand-mark{
  width:40px;height:40px;border-radius:12px;
  display:flex;align-items:center;justify-content:center;
  background:linear-gradient(135deg,var(--primary),var(--primary-2));
  box-shadow:var(--shadow);color:#fff;
}
.brand span{color:var(--primary)}
nav ul{list-style:none;display:flex;gap:24px;flex-wrap:wrap}
nav a{color:var(--muted);font-weight:700}
nav a:hover{color:#fff}
.btn{
  display:inline-flex;align-items:center;justify-content:center;
  padding:14px 22px;border-radius:999px;
  font-weight:800;border:1px solid transparent;
  transition:transform .2s ease,opacity .2s ease;
}
.btn:hover{transform:translateY(-2px);opacity:.98}
.btn-primary{
  background:linear-gradient(135deg,var(--primary),var(--primary-2));
  color:#fff;box-shadow:var(--shadow);
}
.btn-secondary{
  background:rgba(255,255,255,.05);
  border-color:var(--border);color:#fff;
}
.hero{padding:88px 0 60px}
.hero-grid{display:grid;grid-template-columns:1.15fr .85fr;gap:34px;align-items:center}
.eyebrow{
  display:inline-flex;align-items:center;gap:10px;
  padding:8px 14px;border-radius:999px;
  border:1px solid var(--border);
  background:rgba(255,255,255,.05);
  color:#d6e6ff;font-size:.9rem;font-weight:700;
  margin-bottom:18px;
}
.eyebrow::before{
  content:"";width:8px;height:8px;border-radius:50%;
  background:var(--accent);box-shadow:0 0 14px rgba(122,243,209,.6);
}
h1{font-size:clamp(2.4rem,5vw,4.4rem);line-height:1.05;margin-bottom:18px}
h1 .highlight{color:var(--primary)}
.hero p,.section-subtitle,.lead,.article p,.article li{color:var(--muted)}
.hero p{font-size:1.08rem;max-width:760px;margin-bottom:26px}
.hero-actions{display:flex;gap:14px;flex-wrap:wrap;margin-bottom:22px}
.hero-pills{display:flex;gap:10px;flex-wrap:wrap}
.hero-pills span,.tag{
  padding:9px 13px;border-radius:999px;
  background:rgba(255,255,255,.05);
  border:1px solid var(--border);color:var(--muted);
  font-size:.92rem;font-weight:700;
}
.panel{
  background:linear-gradient(180deg, rgba(255,255,255,.06), rgba(255,255,255,.03));
  border:1px solid var(--border);
  border-radius:28px;padding:28px;box-shadow:var(--shadow);
}
.mini-grid,.card-grid,.lesson-grid,.summary-grid{display:grid;gap:22px}
.mini-grid{grid-template-columns:1fr 1fr}
.card-grid{grid-template-columns:repeat(3,1fr)}
.lesson-grid{grid-template-columns:repeat(3,1fr)}
.summary-grid{grid-template-columns:repeat(3,1fr)}
.card,.mini-card{
  background:linear-gradient(180deg,var(--panel),var(--panel-2));
  border:1px solid var(--border);
  border-radius:20px;padding:24px;box-shadow:var(--shadow);
}
.mini-card{padding:18px}
.icon{
  width:54px;height:54px;border-radius:16px;
  display:flex;align-items:center;justify-content:center;
  background:rgba(87,181,255,.14);color:var(--primary);
  font-weight:800;font-size:1.08rem;margin-bottom:16px;
}
.card h3,.mini-card h3{font-size:1.16rem;line-height:1.3;margin-bottom:10px}
.card p,.mini-card p{color:var(--muted);margin-bottom:14px}
.link{color:var(--accent);font-weight:800}
.section-title{font-size:clamp(1.9rem,3vw,2.7rem);line-height:1.15;margin-bottom:14px}
.section-subtitle{font-size:1.03rem;max-width:790px;margin-bottom:34px}
.stats{display:grid;grid-template-columns:repeat(4,1fr);gap:18px}
.stat{
  text-align:center;background:rgba(255,255,255,.04);
  border:1px solid var(--border);border-radius:18px;
  padding:18px;box-shadow:var(--shadow);
}
.stat strong{display:block;color:var(--accent);font-size:1.55rem;margin-bottom:6px}
.lesson-card{display:flex;flex-direction:column;height:100%}
.lesson-number{
  width:44px;height:44px;border-radius:50%;
  display:inline-flex;align-items:center;justify-content:center;
  background:linear-gradient(135deg,var(--primary),var(--primary-2));
  color:#fff;font-weight:800;margin-bottom:16px;
}
.lesson-card p{flex:1}
.lesson-meta{display:flex;gap:10px;flex-wrap:wrap;margin-bottom:16px}
.lesson-meta span{
  padding:7px 10px;border-radius:999px;
  background:rgba(255,255,255,.04);
  border:1px solid var(--border);
  color:#dbe8ff;font-size:.82rem;font-weight:700;
}
.callout{
  background:linear-gradient(180deg,rgba(87,181,255,.12),rgba(255,255,255,.04));
  border:1px solid var(--border);border-radius:24px;
  padding:24px;box-shadow:var(--shadow);
}
footer{
  border-top:1px solid var(--border);
  background:rgba(0,0,0,.18);
  padding:34px 0;
}
.footer-grid{display:grid;grid-template-columns:1.2fr .8fr;gap:26px}
.footer-links{display:flex;flex-wrap:wrap;gap:14px 18px;justify-content:flex-end}
.footer-links a{color:var(--muted)}
.footer-links a:hover{color:#fff}
.copyright{margin-top:18px;color:#94a2cb;font-size:.92rem}
.article{padding:48px 0 70px}
.article-grid{display:grid;grid-template-columns:260px 1fr;gap:26px;align-items:start}
.sidebar{
  position:sticky;top:96px;
  background:linear-gradient(180deg,var(--panel),var(--panel-2));
  border:1px solid var(--border);border-radius:22px;
  padding:22px;box-shadow:var(--shadow);
}
.sidebar h3{font-size:1rem;margin-bottom:12px}
.sidebar ul{list-style:none;display:grid;gap:10px}
.sidebar a{color:var(--muted);font-weight:700}
.sidebar a:hover{color:#fff}
.content{
  background:linear-gradient(180deg,var(--panel),var(--panel-2));
  border:1px solid var(--border);border-radius:26px;
  padding:32px;box-shadow:var(--shadow);
}
.kicker{color:var(--accent);font-weight:800;letter-spacing:.02em;margin-bottom:10px}
.article h1{font-size:clamp(2rem,4vw,3.3rem);margin-bottom:12px}
.lead{font-size:1.08rem;margin-bottom:26px}
.content h2{font-size:1.5rem;margin:26px 0 12px}
.content h3{font-size:1.15rem;margin:20px 0 10px}
.content p{margin-bottom:14px}
.content ul,.content ol{padding-left:20px;margin:10px 0 18px}
.code-block{
  background:#081121;border:1px solid rgba(255,255,255,.08);
  border-radius:18px;padding:18px;overflow:auto;margin:18px 0 18px;
}
.code-block pre{margin:0;color:#dce7ff;font-size:.95rem;line-height:1.6}
.note{
  border-left:4px solid var(--accent);
  background:rgba(255,255,255,.04);
  padding:16px 18px;border-radius:0 16px 16px 0;
  color:#dce7ff;margin:18px 0;
}
.example-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:18px;margin:18px 0 20px}
.example{
  background:rgba(255,255,255,.04);
  border:1px solid var(--border);border-radius:18px;padding:18px;
}
.takeaways, .exercise-list{
  background:rgba(255,255,255,.04);
  border:1px solid var(--border);border-radius:20px;
  padding:20px;margin-top:18px;
}
.nav-pager{
  display:flex;justify-content:space-between;gap:14px;flex-wrap:wrap;
  margin-top:28px;
}
.nav-pager a{
  flex:1;min-width:220px;
  background:rgba(255,255,255,.04);border:1px solid var(--border);
  border-radius:18px;padding:16px 18px;color:#fff;font-weight:700;
}
.nav-pager a span{display:block;color:var(--muted);font-size:.9rem;font-weight:600}
@media (max-width:1024px){
  .hero-grid,.stats,.card-grid,.lesson-grid,.summary-grid,.mini-grid,.footer-grid,.example-grid,.article-grid{grid-template-columns:1fr}
  nav{display:none}
  .footer-links{justify-content:flex-start}
  .sidebar{position:static}
}
@media (max-width:640px){
  .hero{padding-top:70px}
  .section{padding:64px 0}
  .panel,.card,.mini-card,.callout,.content,.sidebar{padding:22px}
  .hero-actions{flex-direction:column;align-items:stretch}
  .btn{width:100%}
}