/* Dark, soft, readable */
:root{
  --bg:#0b0c10; --bg2:#0f1220;
  --card:rgba(255,255,255,.06); --card2:rgba(255,255,255,.09);
  --text:rgba(255,255,255,.92); --muted:rgba(255,255,255,.70);
  --line:rgba(255,255,255,.16);
  --accent:#7dd3fc; --accent2:#a78bfa;
  --radius:22px;
  --shadow: 0 18px 60px rgba(0,0,0,.45);
  --mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas,"Liberation Mono","Courier New", monospace;
  --sans: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial;
  --serif: ui-serif, Georgia, Cambria, "Times New Roman", Times, serif;
}
*{box-sizing:border-box}
html,body{height:100%}
body.bg{
  margin:0;
  font-family:var(--sans);
  color:var(--text);
  background:
    radial-gradient(1200px 600px at 10% 10%, rgba(125,211,252,.18), transparent 60%),
    radial-gradient(900px 500px at 90% 25%, rgba(167,139,250,.16), transparent 55%),
    linear-gradient(180deg, var(--bg), var(--bg2));
}
.center{
  min-height:100vh;
  display:flex; align-items:center; justify-content:center;
  padding:18px;
}
.panel{
  width:min(640px, 100%);
  border:1px solid var(--line);
  background: linear-gradient(180deg, var(--card), rgba(255,255,255,.03));
  border-radius:var(--radius);
  box-shadow:var(--shadow);
  padding:18px;
}
.brand{display:flex; gap:12px; align-items:flex-start;}
.dot{
  width:12px; height:12px; border-radius:999px;
  background: linear-gradient(135deg, var(--accent), var(--accent2));
  box-shadow: 0 0 0 5px rgba(125,211,252,.12);
  margin-top:7px;
}
h1{margin:0 0 6px; font-size:26px; letter-spacing:.2px;}
p{margin:0; color:var(--muted); line-height:1.7}
.alert{
  margin-top:12px;
  border:1px solid rgba(252,165,165,.35);
  background: rgba(252,165,165,.10);
  border-radius:16px;
  padding:10px 12px;
  color: rgba(255,255,255,.92);
}
.form{margin-top:14px; display:flex; flex-direction:column; gap:10px;}
.lbl{font-size:12px; color:var(--muted); font-family:var(--mono);}
.inp{
  padding:12px 12px;
  border-radius:16px;
  border:1px solid var(--line);
  background: var(--card);
  color: var(--text);
  outline:none;
}
.ta{
  width:100%;
  min-height:130px;
  padding:12px 12px;
  border-radius:16px;
  border:1px solid var(--line);
  background: var(--card);
  color: var(--text);
  outline:none;
  resize:vertical;
  font-family: var(--sans);
}
.btn{
  display:inline-flex; align-items:center; justify-content:center;
  padding:10px 14px;
  border-radius:999px;
  border:1px solid var(--line);
  background: var(--card);
  color: var(--text);
  cursor:pointer;
}
.btn:hover{background:var(--card2)}
.btn.primary{
  border-color: rgba(125,211,252,.35);
  background: linear-gradient(135deg, rgba(125,211,252,.18), rgba(167,139,250,.16));
}
.details{
  margin-top:14px;
  border:1px solid var(--line);
  background: rgba(255,255,255,.03);
  border-radius:16px;
  padding:10px 12px;
}
.details summary{cursor:pointer; color: var(--text); font-weight:700;}
.code{
  font-family:var(--mono);
  font-size:12px;
  color:var(--muted);
  border:1px solid var(--line);
  padding:8px 10px;
  border-radius:12px;
  background: rgba(255,255,255,.03);
}
.hint{margin-top:12px; font-size:12px; color:var(--muted); font-family:var(--mono); display:flex; justify-content:space-between; flex-wrap:wrap; gap:10px;}
.top{
  position:sticky; top:0; z-index:20;
  backdrop-filter: blur(14px);
  background: rgba(0,0,0,.22);
  border-bottom:1px solid var(--line);
}
.top-inner{
  max-width:1100px; margin:0 auto;
  padding:14px 18px;
  display:flex; justify-content:space-between; align-items:center; gap:12px;
}
.brand-mini{display:flex; align-items:center; gap:10px;}
.title{font-weight:800; letter-spacing:.2px;}
.nav{display:flex; gap:10px; flex-wrap:wrap;}
.chip{
  padding:8px 12px;
  border-radius:999px;
  border:1px solid transparent;
  color:var(--muted);
}
.chip:hover{border-color:var(--line); background:var(--card)}
.chip.active{border-color:var(--line); background:rgba(255,255,255,.04); color:var(--text)}
.wrap{max-width:1100px; margin:0 auto; padding:22px 18px 70px;}
.hero{
  border:1px solid var(--line);
  background: linear-gradient(180deg, var(--card), rgba(255,255,255,.03));
  border-radius:var(--radius);
  box-shadow:var(--shadow);
  padding:20px;
}
.hero h1{font-size:34px; line-height:1.05; margin:0 0 8px;}
.hero .sub{max-width:80ch;}
.meta{display:flex; gap:10px; flex-wrap:wrap; margin-top:12px;}
.pill{
  font-family:var(--mono);
  font-size:12px;
  color:var(--muted);
  border:1px solid var(--line);
  padding:6px 10px;
  border-radius:999px;
  background:rgba(255,255,255,.03);
}
.card{
  margin-top:16px;
  border:1px solid var(--line);
  background: var(--card);
  border-radius:var(--radius);
  box-shadow:var(--shadow);
  padding:18px;
}
.card h2{margin:0 0 10px; font-size:18px;}
.muted{color:var(--muted); line-height:1.7}
.steps{margin:0; padding-left:18px; color:var(--muted); line-height:1.9}
.chapter{
  margin-top:16px;
  border:1px solid var(--line);
  background: linear-gradient(180deg, var(--card), rgba(255,255,255,.02));
  border-radius:var(--radius);
  box-shadow:var(--shadow);
  padding:18px;
}
.chapter h3{margin:0 0 10px; font-size:18px;}
.chapter p{font-family:var(--serif); font-size:17px; color:var(--text); line-height:1.85}
.list{display:flex; flex-direction:column; gap:12px; margin-top:12px;}
.item{
  border:1px solid var(--line);
  background: linear-gradient(180deg, var(--card), rgba(255,255,255,.02));
  border-radius:18px;
  padding:14px;
}
.item-head{display:flex; justify-content:space-between; align-items:center; gap:12px; flex-wrap:wrap;}
.content{margin-top:10px; color:var(--text); line-height:1.8; font-family:var(--serif); font-size:16px;}
.foot{margin-top:20px; color:var(--muted); font-size:13px; text-align:center;}