:root{
  --bg: #0b0f17;
  --panel: #111827;
  --panel2:#0f172a;
  --text:#e5e7eb;
  --muted:#9ca3af;
  --brand:#60a5fa;
  --brand2:#fb7185;
  --border: rgba(255,255,255,0.10);
  --shadow: 0 14px 40px rgba(0,0,0,0.40);
  --radius: 16px;
  --max: 1100px;
}
@media (prefers-color-scheme: light){
  :root{
    --bg:#f7fafc;
    --panel:#ffffff;
    --panel2:#ffffff;
    --text:#0b1220;
    --muted:#4b5563;
    --brand:#2563eb;
    --brand2:#db2777;
    --border: rgba(0,0,0,0.10);
    --shadow: 0 14px 40px rgba(16,24,40,0.10);
  }
}
*{box-sizing:border-box}
html,body{height:100%}
body{
  margin:0;
  font-family: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, "Apple Color Emoji", "Segoe UI Emoji";
  color:var(--text);
  background: radial-gradient(1200px 600px at 15% -10%, rgba(96,165,250,0.35), transparent 60%),
              radial-gradient(1000px 600px at 90% 0%, rgba(251,113,133,0.25), transparent 55%),
              var(--bg);
  line-height:1.55;
}
a{color:inherit}
.container{max-width:var(--max); margin:0 auto; padding:0 18px}
.skip{
  position:absolute; left:-999px; top:auto; width:1px; height:1px; overflow:hidden;
}
.skip:focus{
  left:18px; top:12px; width:auto; height:auto; padding:10px 12px; border:1px solid var(--border);
  background:var(--panel); border-radius:12px; z-index:9999;
}
.header{
  position:sticky; top:0; z-index:1000;
  backdrop-filter: blur(14px);
  background: linear-gradient(to bottom, rgba(0,0,0,0.35), rgba(0,0,0,0.10));
  border-bottom:1px solid var(--border);
}
@media (prefers-color-scheme: light){
  .header{background: rgba(255,255,255,0.65)}
}
.header__inner{
  display:flex; align-items:center; justify-content:space-between;
  max-width:var(--max); margin:0 auto; padding:14px 18px;
}
.brand{display:flex; align-items:center; gap:12px}
.brand__mark{
  width:40px; height:40px; border-radius:14px; display:grid; place-items:center;
  background: linear-gradient(135deg, rgba(96,165,250,0.95), rgba(251,113,133,0.85));
  box-shadow: var(--shadow);
  text-decoration:none;
}
.brand__dot{
  width:14px; height:14px; border-radius:999px; background: rgba(255,255,255,0.90);
  box-shadow: 0 4px 10px rgba(0,0,0,0.25);
}
.brand__text{display:flex; flex-direction:column}
.brand__name{font-weight:800; letter-spacing:-0.02em; text-decoration:none}
.brand__tagline{font-size:13px; color:var(--muted); margin-top:2px}

.navtoggle{
  display:none;
  border:1px solid var(--border);
  background:rgba(255,255,255,0.06);
  border-radius:12px;
  padding:10px 10px;
}
.navtoggle span{
  display:block; width:20px; height:2px; background:var(--text);
  margin:4px 0; border-radius:999px;
}
@media (max-width: 980px){
  .navtoggle{display:block}
}
.nav{
  border-top:1px solid var(--border);
}
.nav__inner{
  max-width:var(--max); margin:0 auto; padding:10px 18px;
  display:flex; flex-wrap:wrap; gap:10px;
  align-items:center; justify-content:space-between;
}
.nav__meta{display:flex; gap:10px; align-items:center}
.nav__link{
  display:inline-flex; padding:8px 10px; border-radius:999px;
  border:1px solid transparent; text-decoration:none;
  color:var(--muted);
  font-size:14px;
}
.nav__link:hover{border-color:var(--border); color:var(--text); background:rgba(255,255,255,0.05)}
.nav__link--active{color:var(--text); border-color:rgba(96,165,250,0.55); background:rgba(96,165,250,0.10)}
@media (max-width: 980px){
  .nav{display:none}
  .nav.is-open{display:block}
  .nav__inner{flex-direction:column; align-items:stretch}
  .nav__meta{justify-content:flex-start}
}

.main{padding-bottom:32px}
.hero{
  padding:34px 0 12px;
}
.hero__title{
  font-size: clamp(28px, 3.4vw, 44px);
  line-height:1.10;
  margin:0 0 8px;
  letter-spacing:-0.03em;
}
.hero__lead{margin:0; color:var(--muted); font-size: 16px; max-width: 75ch}
.hero__note{margin:12px 0 0; color:var(--text); opacity:0.9; max-width: 75ch}

.section{padding:18px 0 28px}
.hr{border:0; border-top:1px solid var(--border); margin:26px 0}

.grid{display:grid; gap:14px}
.grid--2{grid-template-columns: repeat(2, minmax(0, 1fr))}
.grid--3{grid-template-columns: repeat(3, minmax(0, 1fr))}
@media (max-width: 900px){
  .grid--2,.grid--3{grid-template-columns: 1fr}
}

.cards{display:grid; grid-template-columns: repeat(2, minmax(0,1fr)); gap:14px}
@media (max-width: 900px){ .cards{grid-template-columns:1fr} }

.card{
  display:block;
  padding:16px 16px;
  border-radius: var(--radius);
  border:1px solid var(--border);
  background: linear-gradient(180deg, rgba(255,255,255,0.06), rgba(255,255,255,0.02));
  box-shadow: var(--shadow);
  text-decoration:none;
  position:relative;
  overflow:hidden;
}
@media (prefers-color-scheme: light){
  .card{background: linear-gradient(180deg, rgba(37,99,235,0.05), rgba(255,255,255,0.60))}
}
.card:before{
  content:"";
  position:absolute; inset:-60px -60px auto auto; width:140px; height:140px;
  background: radial-gradient(circle at 30% 30%, rgba(96,165,250,0.65), transparent 60%);
  transform: rotate(20deg);
}
.card__title{font-weight:800; letter-spacing:-0.01em}
.card__body{color:var(--muted); margin-top:6px}
.card__cta{margin-top:10px; font-weight:650; color:rgba(96,165,250,0.95)}
.card:hover{transform: translateY(-1px); transition: 120ms ease; border-color: rgba(96,165,250,0.45)}

.panel{
  padding:16px 16px;
  border-radius: var(--radius);
  border:1px solid var(--border);
  background: rgba(255,255,255,0.04);
}
@media (prefers-color-scheme: light){
  .panel{background: rgba(255,255,255,0.85)}
}
.panel h3,.panel h4{margin-top:0}

.callout{
  border-radius: var(--radius);
  border:1px solid rgba(96,165,250,0.45);
  background: rgba(96,165,250,0.12);
  padding:14px 14px;
  margin:16px 0;
}
.callout__title{font-weight:800; margin-bottom:6px}
.muted{color:var(--muted)}

.chips{display:flex; flex-wrap:wrap; gap:10px; margin:10px 0 0}
.chip{
  text-decoration:none; color:var(--text);
  border:1px solid var(--border);
  padding:8px 12px; border-radius:999px;
  background: rgba(255,255,255,0.04);
}
.chip:hover{border-color: rgba(251,113,133,0.45); background: rgba(251,113,133,0.10)}

.btn{
  display:inline-flex; align-items:center; justify-content:center; gap:10px;
  padding:10px 12px;
  border-radius:12px;
  border:1px solid rgba(96,165,250,0.55);
  background: rgba(96,165,250,0.18);
  color:var(--text);
  text-decoration:none;
  font-weight:650;
  cursor:pointer;
}
.btn--ghost{
  border-color:var(--border);
  background: rgba(255,255,255,0.04);
}
.btn:hover{filter: brightness(1.06)}

.prose h2{margin-top:0}
.prose h3{margin-top:22px}
.prose p, .prose li{max-width: 80ch}
.prose details{border:1px solid var(--border); border-radius: var(--radius); padding:12px 12px; margin:10px 0; background: rgba(255,255,255,0.03)}
.prose summary{cursor:pointer; font-weight:700}
.prose ul, .prose ol{padding-left:20px}

.form{display:grid; gap:10px}
label{display:grid; gap:6px; font-size:14px; color:var(--muted)}
input{
  border-radius:12px;
  border:1px solid var(--border);
  background: rgba(255,255,255,0.04);
  padding:10px 12px;
  color:var(--text);
  outline:none;
}
input:focus{border-color: rgba(96,165,250,0.55); box-shadow: 0 0 0 4px rgba(96,165,250,0.15)}
.form__out{margin-top:6px; color:var(--text)}
.codebox{
  border:1px solid var(--border); background: rgba(0,0,0,0.25);
  border-radius: var(--radius); padding:12px 12px; overflow:auto;
}
@media (prefers-color-scheme: light){ .codebox{background: rgba(255,255,255,0.90)} }

.quiz{border:1px solid var(--border); border-radius: var(--radius); padding:14px 14px; background: rgba(255,255,255,0.03)}
.quiz__q{font-weight:750}
.quiz__answers{display:flex; gap:10px; flex-wrap:wrap; margin-top:10px}
.quiz__result{margin-top:10px; color:var(--muted)}

.footer{
  border-top:1px solid var(--border);
  padding:24px 0 34px;
  background: rgba(0,0,0,0.18);
}
@media (prefers-color-scheme: light){ .footer{background: rgba(255,255,255,0.70)} }
.footer__grid{display:grid; grid-template-columns: 2fr 1fr 1fr; gap:16px}
@media (max-width: 900px){ .footer__grid{grid-template-columns: 1fr} }
.footer__title{font-weight:800; margin-bottom:6px}
.link{color: rgba(96,165,250,0.95); text-decoration:none}
.link:hover{text-decoration:underline}

.select{
  border-radius:12px;
  border:1px solid var(--border);
  background: rgba(255,255,255,0.04);
  padding:10px 12px;
  color:var(--text);
  outline:none;
}
.select:focus{border-color: rgba(96,165,250,0.55); box-shadow: 0 0 0 4px rgba(96,165,250,0.15)}
code{font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace}

.checks{display:grid; gap:8px}
.check{
  display:flex; gap:10px; align-items:flex-start;
  font-size:14px; color:var(--muted);
}
.check input{margin-top:3px}