:root{
  --bg:#06131f;--panel:#0b2032;--panel2:#102b41;--line:#23445c;
  --text:#edf8ff;--muted:#9db6c8;--accent:#2fd3c6;--accent2:#ffb85c;
  --good:#4ee09a;--bad:#ff6b78;--shadow:0 18px 45px rgba(0,0,0,.25);
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;font-family:Inter,ui-sans-serif,system-ui,-apple-system,Segoe UI,Roboto,Arial,sans-serif;background:
radial-gradient(circle at 10% 0%,#123e58 0,transparent 34%),
linear-gradient(180deg,#06131f,#081a29 55%,#05101a);color:var(--text);min-height:100vh}
button,input,select{font:inherit}
button{cursor:pointer}
a{color:var(--accent)}
.app{max-width:1120px;margin:auto;padding:18px 18px 110px}
header{display:flex;justify-content:space-between;align-items:center;gap:15px;padding:8px 0 24px;flex-wrap:wrap}
.brand{display:flex;align-items:center;gap:12px}
.logo{width:48px;height:48px;border-radius:16px;background:linear-gradient(135deg,var(--accent),#168ac5);display:grid;place-items:center;font-size:25px;box-shadow:var(--shadow)}
h1{font-size:1.18rem;margin:0}.subtitle{font-size:.83rem;color:var(--muted);margin-top:3px}
.streak{background:#142d40;border:1px solid var(--line);border-radius:999px;padding:9px 12px;font-size:.82rem}
.view{display:none}.view.active{display:block}
.card{background:linear-gradient(145deg,rgba(16,43,65,.95),rgba(8,29,45,.96));border:1px solid var(--line);border-radius:24px;padding:22px;box-shadow:var(--shadow)}
.btn{border:0;border-radius:14px;padding:12px 17px;font-weight:750;background:var(--accent);color:#042021;transition:.18s transform,.18s opacity}
.btn:hover{transform:translateY(-2px)}.btn:focus-visible{outline:2px solid var(--accent2);outline-offset:2px}
.btn.secondary{background:#17364c;color:var(--text);border:1px solid var(--line)}
.btn.small{padding:9px 12px;font-size:.86rem}
.btn.hero-btn{font-size:1.05rem;padding:16px 24px}
.btn.danger{background:var(--bad);color:#fff}
.actions{display:flex;gap:11px;flex-wrap:wrap}
.badge{display:inline-flex;align-items:center;gap:6px;background:#143046;border:1px solid var(--line);border-radius:999px;padding:6px 10px;color:var(--muted);font-size:.78rem}
.badge-verified{border-color:var(--good);color:var(--good)}
.badge-local{border-color:var(--accent2);color:var(--accent2)}
.badge-mnemonic{border-color:#b39ddb;color:#b39ddb}
.notice{font-size:.78rem;color:var(--muted);margin-top:18px;line-height:1.4}
.nav{position:fixed;left:50%;bottom:14px;transform:translateX(-50%);z-index:20;width:min(98%,760px);background:rgba(7,24,37,.92);backdrop-filter:blur(18px);border:1px solid var(--line);border-radius:20px;padding:8px;display:grid;grid-template-columns:repeat(6,1fr);box-shadow:var(--shadow)}
.nav button{background:transparent;border:0;color:var(--muted);padding:9px 5px;border-radius:14px;font-size:.7rem}
.nav button span{display:block;font-size:1.1rem;margin-bottom:2px}
.nav button.active{background:#17364c;color:var(--text)}
.hero{display:grid;grid-template-columns:1.35fr .65fr;gap:18px;margin-bottom:22px}
.hero h2{font-size:clamp(1.65rem,4vw,2.8rem);line-height:1.04;margin:0 0 13px}
.hero p{color:var(--muted);line-height:1.55;margin:0 0 20px}
.progress-ring{width:142px;height:142px;border-radius:50%;display:grid;place-items:center;margin:auto;background:conic-gradient(var(--accent) var(--progress),#17364c 0)}
.progress-ring::before{content:"";position:absolute;width:108px;height:108px;border-radius:50%;background:#0d2639}
.ring-wrap{position:relative;display:grid;place-items:center}.ring-text{position:absolute;text-align:center;z-index:2}.ring-text b{font-size:1.8rem;display:block}.ring-text span{color:var(--muted);font-size:.76rem}
.stats{display:grid;grid-template-columns:repeat(3,1fr);gap:12px;margin:14px 0 22px}
.stat{background:#0d2639;border:1px solid var(--line);border-radius:18px;padding:16px}.stat b{display:block;font-size:1.35rem}.stat span{font-size:.78rem;color:var(--muted)}
.section-head{display:flex;justify-content:space-between;align-items:end;gap:15px;margin:28px 0 13px;flex-wrap:wrap}.section-head h2{margin:0;font-size:1.25rem}.section-head p{margin:4px 0 0;color:var(--muted);font-size:.86rem}
.grid{display:grid;grid-template-columns:repeat(3,1fr);gap:14px}
.grid-2{grid-template-columns:repeat(2,1fr)}
.menu-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:12px;margin:18px 0}
.menu-item{text-align:left;padding:18px;border-radius:18px;border:1px solid var(--line);background:#0d2639;color:var(--text);transition:.15s border-color}
.menu-item:hover,.menu-item:focus-visible{border-color:var(--accent);outline:none}
.menu-item.primary{border-color:var(--accent);background:linear-gradient(145deg,#103a46,#0b2032)}
.menu-item h3{margin:0 0 6px;font-size:1rem}.menu-item p{margin:0;color:var(--muted);font-size:.82rem}
.module{position:relative;overflow:hidden;min-height:160px}.module h3{margin:10px 0 6px}.module p{color:var(--muted);font-size:.88rem;line-height:1.42;margin:0 0 12px}
.lesson-layout{display:grid;grid-template-columns:280px 1fr;gap:16px}.lesson-list{display:flex;flex-direction:column;gap:8px}
.lesson-item{border:1px solid var(--line);background:#0c2436;color:var(--text);text-align:left;border-radius:14px;padding:12px}
.lesson-item.active{border-color:var(--accent);background:#103a46}
.lesson-content h2{margin-top:0}.lesson-content h3{margin-top:23px}
.lesson-content p,.lesson-content li{color:#c1d3df;line-height:1.62}
.lesson-content .rule{border-left:4px solid var(--accent2);padding:13px 15px;background:#122b3d;border-radius:0 14px 14px 0;margin:16px 0}
.lesson-content table{width:100%;border-collapse:collapse;margin:15px 0}
.lesson-content td,.lesson-content th{border-bottom:1px solid var(--line);padding:11px;text-align:left}
.lesson-content th{color:var(--accent)}
.visual-box{display:flex;justify-content:center;gap:16px;flex-wrap:wrap;margin:20px 0;padding:16px;background:#0a1e2e;border-radius:16px}
.quiz-wrap{max-width:760px;margin:auto}
.quiz-top{display:flex;justify-content:space-between;align-items:center;margin-bottom:14px;flex-wrap:wrap;gap:8px}
.quiz-progress{height:8px;background:#17364c;border-radius:10px;overflow:hidden;margin-bottom:8px}
.quiz-progress i{height:100%;display:block;background:var(--accent);width:0;transition:width .3s}
.question{font-size:1.2rem;line-height:1.4;margin:20px 0 16px}
.answers{display:grid;gap:10px}
.answer{border:1px solid var(--line);background:#102b41;color:var(--text);border-radius:15px;padding:14px;text-align:left;width:100%}
.answer:hover{border-color:#4b718b}.answer:focus-visible{outline:2px solid var(--accent);outline-offset:2px}
.answer.good{border-color:var(--good);background:rgba(78,224,154,.12)}
.answer.bad{border-color:var(--bad);background:rgba(255,107,120,.12)}
.answer.marked{border-color:var(--accent2)}
.explain{margin-top:15px;padding:14px;background:#0b2032;border-radius:14px;color:#c9d9e3;line-height:1.5}
.explain.hidden{display:none}
.quiz-controls{display:flex;justify-content:space-between;margin-top:16px;flex-wrap:wrap;gap:8px}
.exam-nav{display:flex;gap:8px;flex-wrap:wrap;margin:12px 0}
.exam-dot{width:28px;height:28px;border-radius:8px;border:1px solid var(--line);background:#102b41;color:var(--muted);font-size:.72rem}
.exam-dot.answered{background:#1a4a5a;color:var(--text)}
.exam-dot.marked{border-color:var(--accent2)}
.exam-dot.current{border-color:var(--accent);color:var(--accent)}
.result{text-align:center;padding:28px}.result .score{font-size:3.4rem;font-weight:850;color:var(--accent)}
.flashcard{min-height:300px;display:grid;place-items:center;text-align:center;perspective:1000px;cursor:pointer}
.flash-inner{width:100%;min-height:260px;position:relative;transition:transform .55s;transform-style:preserve-3d}
.flashcard.flipped .flash-inner{transform:rotateY(180deg)}
.face{position:absolute;inset:0;backface-visibility:hidden;border:1px solid var(--line);border-radius:24px;background:linear-gradient(145deg,#123149,#0b2032);padding:30px;display:grid;place-items:center}
.face.back{transform:rotateY(180deg);background:linear-gradient(145deg,#124044,#0b2b34)}
.face small{display:block;color:var(--muted);margin-bottom:15px}.face strong{font-size:1.4rem;line-height:1.35}
.error-list{list-style:none;padding:0;margin:0}.error-list li{padding:12px;border-bottom:1px solid var(--line)}
.source-table{width:100%;border-collapse:collapse;font-size:.85rem}
.source-table th,.source-table td{border-bottom:1px solid var(--line);padding:10px;text-align:left;vertical-align:top}
.code-modes{display:grid;grid-template-columns:repeat(auto-fit,minmax(140px,1fr));gap:10px;margin:16px 0}
@media(max-width:800px){.hero,.lesson-layout{grid-template-columns:1fr}.hero .card:last-child{display:none}.grid{grid-template-columns:1fr 1fr}.stats{grid-template-columns:1fr 1fr 1fr}}
@media(max-width:520px){.app{padding:12px 12px var(--nav-offset)}.grid,.grid-2,.menu-grid{grid-template-columns:1fr}}
@media(prefers-reduced-motion:reduce){*{animation-duration:.01ms!important;transition-duration:.01ms!important}.flash-inner{transition:none}}