:root{
  --bg:#020817;
  --bg2:#0f172a;
  --panel:rgba(15,23,42,.82);
  --panel2:rgba(2,6,23,.72);
  --border:#1f2a44;
  --text:#e5eefb;
  --muted:#94a3b8;
  --accent:#10b981;
  --accent2:#06b6d4;
  --ok:#16a34a;
  --warn:#f59e0b;
  --bad:#ef4444;
  --shadow:0 20px 50px rgba(0,0,0,.28);
  --radius:28px;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{
  margin:0;
  font-family:Inter,Segoe UI,Arial,sans-serif;
  background:
    radial-gradient(circle at top left, rgba(16,185,129,.08), transparent 28%),
    radial-gradient(circle at top right, rgba(6,182,212,.08), transparent 24%),
    linear-gradient(180deg,#020617 0%,#07111f 100%);
  color:var(--text);
}
a{text-decoration:none;color:inherit}
.container{max-width:1280px;margin:0 auto;padding:24px}
.header{
  display:flex;gap:24px;justify-content:space-between;align-items:flex-start;
  padding:28px;border:1px solid var(--border);border-radius:30px;
  background:var(--panel);box-shadow:var(--shadow);backdrop-filter:blur(10px);
}
.badges{display:flex;gap:10px;flex-wrap:wrap;margin-bottom:14px}
.badge{
  display:inline-flex;align-items:center;gap:8px;padding:8px 14px;border-radius:999px;
  border:1px solid var(--border);color:#cbd5e1;font-size:14px;font-weight:600;
  background:rgba(15,23,42,.6)
}
.badge.primary{
  background:rgba(16,185,129,.16);
  border-color:rgba(16,185,129,.35);
  color:#ecfdf5;
}
.hero-title{margin:0;font-size:40px;line-height:1.08;max-width:820px}
.hero-subtitle{margin:12px 0 0;color:var(--muted);line-height:1.7;max-width:800px}
.progress-card{
  width:360px;max-width:100%;padding:18px;border-radius:24px;
  border:1px solid var(--border);background:var(--panel2)
}
.progress-row{display:flex;justify-content:space-between;font-size:14px;color:#cbd5e1;margin-bottom:10px}
.progress-track{
  height:12px;border-radius:999px;background:#081121;overflow:hidden;border:1px solid var(--border)
}
.progress-fill{
  height:100%;width:0%;
  background:linear-gradient(90deg,var(--accent),var(--accent2));
  transition:width .25s ease;
}
.actions{display:flex;gap:10px;flex-wrap:wrap;margin-top:14px}
.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:8px;
  min-height:42px;padding:10px 16px;border-radius:18px;
  border:1px solid var(--border);font-weight:700;cursor:pointer;transition:.18s ease;
}
.btn:hover{transform:translateY(-1px)}
.btn.primary{background:var(--accent);border-color:transparent;color:white}
.btn.primary:hover{background:#0ea371}
.btn.secondary{background:#1e293b;color:white}
.btn.outline{background:transparent;color:#e2e8f0}
.grid-hero{display:grid;grid-template-columns:1.1fr .9fr;gap:24px;margin-top:28px}
.card{
  border:1px solid var(--border);background:var(--panel);
  border-radius:var(--radius);padding:24px;box-shadow:var(--shadow)
}
.card h2,.card h3{margin:0 0 14px}
.card p{color:#cbd5e1;line-height:1.75}
.steps .step,.soft-box,.tool,.command,.interp,.quiz-item,.level-summary{
  background:rgba(2,6,23,.55);border:1px solid var(--border);border-radius:22px;padding:16px
}
.section-head{
  display:flex;justify-content:space-between;align-items:center;gap:16px;margin:34px 0 16px
}
.section-head h2{margin:0;font-size:30px}
.level-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:20px}
.level-card{height:100%;display:flex;flex-direction:column}
.level-top{display:flex;justify-content:space-between;gap:12px;align-items:flex-start;margin-bottom:18px}
.icon-wrap{
  width:52px;height:52px;border-radius:18px;background:rgba(16,185,129,.12);
  display:flex;align-items:center;justify-content:center;font-size:26px
}
.status{
  padding:8px 12px;border-radius:999px;border:1px solid var(--border);
  background:rgba(15,23,42,.55);color:#cbd5e1;font-size:13px;font-weight:600
}
.status.done{
  background:rgba(22,163,74,.16);border-color:rgba(22,163,74,.35);color:#ecfdf5
}
.level-card p{flex:1}
.level-card .btn{margin-top:6px;width:100%}
.level-page-title{font-size:34px;line-height:1.2;margin:0 0 10px}
.level-layout,.level-layout-2{display:grid;gap:24px;margin-top:24px}
.level-layout{grid-template-columns:1fr 1fr}
.level-layout-2{grid-template-columns:.92fr 1.08fr}
.tool{margin-bottom:12px}
.tool:last-child,.command:last-child,.interp:last-child{margin-bottom:0}
.metric-wrap{display:flex;flex-wrap:wrap;gap:10px}
.metric{
  border-radius:999px;padding:10px 14px;
  border:1px solid var(--border);background:rgba(2,6,23,.55);color:#e2e8f0
}
pre{
  margin:12px 0 0;padding:16px;border-radius:20px;overflow:auto;
  background:rgba(0,0,0,.35);color:#a7f3d0;border:1px solid rgba(255,255,255,.04);
  font-size:14px;line-height:1.6
}
.quiz-option{
  display:block;width:100%;padding:0;margin:0;background:none;border:none
}
.quiz-option-inner{
  width:100%;display:block;text-align:left;padding:14px 16px;border-radius:18px;
  border:1px solid var(--border);background:#0f172a;color:#e2e8f0;cursor:pointer;transition:.18s ease
}
.quiz-option input{display:none}
.quiz-option input:checked + .quiz-option-inner{
  border-color:#0891b2;background:rgba(8,145,178,.12)
}
.quiz-option.correct .quiz-option-inner{
  border-color:var(--ok);background:rgba(22,163,74,.12)
}
.quiz-option.wrong .quiz-option-inner{
  border-color:var(--bad);background:rgba(239,68,68,.12)
}
.quiz-expl{display:none;margin-top:12px;color:#cbd5e1}
.quiz-expl.show{display:block}
.result{
  margin-top:16px;padding:14px 16px;border-radius:18px;font-size:14px;font-weight:600
}
.result.pass{background:rgba(22,163,74,.12);color:#dcfce7}
.result.fail{background:rgba(245,158,11,.12);color:#fde68a}
.footer-nav{display:flex;justify-content:space-between;gap:12px;flex-wrap:wrap;margin:24px 0 10px}
.muted{color:var(--muted)}
@media (max-width: 1024px){
  .header,.grid-hero,.level-layout,.level-layout-2,.level-grid{grid-template-columns:1fr}
  .hero-title{font-size:32px}
}
@media (max-width: 640px){
  .container{padding:14px}
  .header,.card{padding:18px}
  .hero-title{font-size:28px}
  .section-head h2{font-size:24px}
}