*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
:root{--brand:#4f46e5;--brand2:#7c3aed;--ink:#1a1a2e;--mute:#6b7280;--line:#e9ecef;--bg:#f5f6fa;--card:#fff;--ok:#15803d;--okbg:#f0fdf4;--err:#b91c1c;--errbg:#fef2f2;--gold:#b48c28;--grad:linear-gradient(135deg,#4f46e5,#7c3aed)}
html{scroll-behavior:smooth}
body{font-family:'Inter',system-ui,sans-serif;background:var(--bg);color:var(--ink);line-height:1.55;font-size:15px;-webkit-font-smoothing:antialiased}
a{color:inherit;text-decoration:none}img{max-width:100%}
:focus-visible{outline:2.5px solid var(--brand);outline-offset:2px;border-radius:6px}
.wrap{max-width:1160px;margin:0 auto;padding:28px 18px 70px}
.narrow{max-width:760px}
/* nav */
.nav{background:#fff;border-bottom:1px solid var(--line);position:sticky;top:0;z-index:50}
.nav-in{max-width:1160px;margin:0 auto;padding:0 18px;height:64px;display:flex;align-items:center;gap:22px}
.brand{display:flex;align-items:center;gap:9px;font-weight:800;font-size:17px}.brand img{height:30px}.brand b{background:var(--grad);-webkit-background-clip:text;background-clip:text;color:transparent}
.links{display:flex;align-items:center;gap:4px;margin-left:auto}
.links a{padding:8px 13px;border-radius:9px;font-weight:600;font-size:14px;color:var(--mute)}
.links a:hover,.links a.on{background:#eef0ff;color:var(--brand)}
.burger{display:none;margin-left:auto;background:none;border:1px solid var(--line);border-radius:9px;width:40px;height:40px;font-size:16px}
@media(max-width:820px){.burger{display:block}.links{display:none;position:absolute;top:64px;left:0;right:0;background:#fff;border-bottom:1px solid var(--line);flex-direction:column;align-items:stretch;padding:10px 18px}body.menu .links{display:flex}}
/* buttons / forms */
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;padding:11px 20px;border-radius:10px;border:1.5px solid var(--line);background:#fff;font:600 14px 'Inter',sans-serif;cursor:pointer;color:var(--ink);transition:transform .15s,box-shadow .15s}
.btn:hover{transform:translateY(-1px)}.btn:disabled{opacity:.5;cursor:not-allowed;transform:none}
.btn-p{background:var(--grad);color:#fff;border:none}.btn-p:hover{box-shadow:0 6px 20px rgba(79,70,229,.3)}
.btn-ok{background:#12896f;color:#fff;border:none}.btn-danger{color:var(--err);border-color:#fecaca}
.btn-sm{padding:7px 12px;font-size:13px}.btn-block{width:100%}
label.l{display:block;font-size:13px;font-weight:600;color:#374151;margin-bottom:6px}
.in,select.in,textarea.in{width:100%;border:1.5px solid #e5e7eb;border-radius:9px;padding:11px 14px;font:14px 'Inter',sans-serif;color:var(--ink);background:#fff}
.in:focus{border-color:var(--brand);box-shadow:0 0 0 3px rgba(79,70,229,.12);outline:none}
textarea.in{resize:vertical;min-height:110px}.fg{margin-bottom:16px}
.alert{border-radius:9px;padding:11px 14px;font-size:14px;margin-bottom:16px;display:flex;gap:8px;align-items:center}
.alert.ok{background:var(--okbg);border:1px solid #bbf7d0;color:var(--ok)}.alert.err{background:var(--errbg);border:1px solid #fecaca;color:var(--err)}
/* cards */
.card{background:var(--card);border:1px solid var(--line);border-radius:16px;padding:24px;box-shadow:0 4px 30px rgba(0,0,0,.04)}
.card+.card{margin-top:18px}
h1.t{font-size:1.7rem;font-weight:800;letter-spacing:-.02em}h2.t{font-size:1.2rem;font-weight:800;margin-bottom:14px}
.sub{color:var(--mute);font-size:14px}.pagehead{margin-bottom:24px}
.grid{display:grid;gap:18px;grid-template-columns:repeat(auto-fill,minmax(260px,1fr))}
.stats{display:grid;grid-template-columns:repeat(auto-fit,minmax(150px,1fr));gap:14px;margin-bottom:24px}
.stat{background:#fff;border:1px solid var(--line);border-radius:14px;padding:16px 18px}.stat b{display:block;font-size:1.6rem;font-weight:800}.stat span{font-size:12.5px;color:var(--mute);font-weight:600}
.stat i{color:var(--brand);margin-right:6px}
.ccard{background:#fff;border:1px solid var(--line);border-radius:16px;overflow:hidden;display:flex;flex-direction:column;transition:transform .15s,box-shadow .15s}
.ccard:hover{transform:translateY(-3px);box-shadow:0 14px 34px -16px rgba(79,70,229,.35)}
.cthumb{height:110px;display:flex;align-items:center;justify-content:center;color:rgba(255,255,255,.92);font-size:40px;position:relative}
.chip{position:absolute;top:10px;left:10px;background:rgba(255,255,255,.2);backdrop-filter:blur(4px);color:#fff;font-size:11.5px;font-weight:700;padding:3px 10px;border-radius:99px}
.cbody{padding:16px 18px 18px;display:flex;flex-direction:column;gap:6px;flex:1}.ccat{font-size:12px;font-weight:700;color:var(--brand)}
.cbody h3{font-size:16px;font-weight:700;line-height:1.3}.cbody p{font-size:13.5px;color:var(--mute);flex:1}
.cmeta{display:flex;gap:14px;font-size:12.5px;color:var(--mute);margin-top:6px}
.bar{height:7px;background:#eceef5;border-radius:99px;overflow:hidden;margin-top:8px}.bar>i{display:block;height:100%;background:var(--grad);border-radius:99px;transition:width .6s}
.tabs{display:flex;gap:8px;flex-wrap:wrap;margin-bottom:20px}.tabs a{padding:7px 15px;border-radius:99px;border:1.5px solid var(--line);background:#fff;font-size:13px;font-weight:600;color:var(--mute)}.tabs a.on{background:var(--grad);color:#fff;border-color:transparent}
.pill{display:inline-block;padding:3px 10px;border-radius:99px;font-size:11.5px;font-weight:700;background:#eef0ff;color:var(--brand)}.pill.g{background:var(--okbg);color:var(--ok)}.pill.y{background:#fffbeb;color:#92400e}
/* auth */
.auth{min-height:calc(100vh - 64px);display:flex;align-items:center;justify-content:center;padding:36px 16px}
.auth .card{width:100%;max-width:440px;padding:36px}.auth h1{text-align:center;font-size:1.5rem;font-weight:800}.auth .sub{text-align:center;margin:4px 0 24px}
.foot{text-align:center;font-size:14px;color:var(--mute);margin-top:22px}.foot a{color:var(--brand);font-weight:600}
/* hero */
.hero{background:var(--grad);color:#fff;padding:70px 18px 80px;position:relative;overflow:hidden}
.hero::after{content:"";position:absolute;inset:0;background:radial-gradient(circle at 85% 20%,rgba(255,255,255,.18),transparent 45%);pointer-events:none}
.hero-in{max-width:1160px;margin:0 auto;position:relative}.hero h1{font-size:clamp(2rem,5vw,3.3rem);font-weight:800;letter-spacing:-.03em;line-height:1.1;max-width:720px}
.hero p{margin:16px 0 26px;font-size:1.1rem;max-width:560px;opacity:.92}.hero .btn{border:none}.hero .btn-w{background:#fff;color:var(--brand)}.hero .btn-o{background:rgba(255,255,255,.15);color:#fff}
.code-chip{display:inline-block;font-family:ui-monospace,Menlo,monospace;font-size:12.5px;background:rgba(0,0,0,.25);padding:4px 11px;border-radius:7px;margin-bottom:18px}
.feat{display:grid;grid-template-columns:repeat(auto-fit,minmax(230px,1fr));gap:18px;margin:34px 0}
.feat div{background:#fff;border:1px solid var(--line);border-radius:14px;padding:20px}.feat i{font-size:20px;color:var(--brand);margin-bottom:10px}.feat b{display:block;margin-bottom:4px}.feat p{font-size:13.5px;color:var(--mute)}
/* course page */
.chead{background:var(--grad);color:#fff;border-radius:18px;padding:30px;margin-bottom:22px}
.chead h1{font-size:1.8rem;font-weight:800;letter-spacing:-.02em}.chead p{opacity:.92;margin:8px 0 16px;max-width:640px}
.cols{display:grid;grid-template-columns:1fr 300px;gap:22px;align-items:start}@media(max-width:900px){.cols{grid-template-columns:1fr}}
details.mod{background:#fff;border:1px solid var(--line);border-radius:12px;margin-bottom:10px}details.mod summary{cursor:pointer;padding:14px 18px;font-weight:700;list-style:none;display:flex;justify-content:space-between;gap:10px}
details.mod summary::-webkit-details-marker{display:none}.lrow{display:flex;align-items:center;gap:10px;padding:10px 18px;border-top:1px solid var(--line);font-size:14px}.lrow:hover{background:#f9f9ff}.lrow .ck{color:#cbd0dd}.lrow .ck.d{color:#12896f}.lrow small{margin-left:auto;color:var(--mute)}
/* lesson */
.lgrid{display:grid;grid-template-columns:300px 1fr;gap:22px;align-items:start}@media(max-width:900px){.lgrid{grid-template-columns:1fr}}
.side{position:sticky;top:84px;max-height:calc(100vh - 100px);overflow:auto}@media(max-width:900px){.side{position:static;max-height:none}}
.lhero{background:var(--grad);color:#fff;border-radius:16px;padding:24px 26px;margin-bottom:18px}.lhero h1{font-size:1.6rem;font-weight:800;letter-spacing:-.02em}.lhero div{font-size:13px;opacity:.9;margin-top:6px}
.prose{font-size:16.5px;line-height:1.8}.prose h2{font-size:1.4rem;margin:1.6em 0 .5em;font-weight:800}.prose h3{font-size:1.15rem;margin:1.4em 0 .4em;font-weight:700}
.prose p{margin-bottom:1.1em}.prose ul,.prose ol{margin:0 0 1.1em 1.4em}.prose li{margin-bottom:.4em}
.prose pre{background:#0f172a;color:#e2e8f0;padding:16px 18px;border-radius:12px;overflow-x:auto;margin:1.2em 0;font-size:13.5px;line-height:1.6}
.prose code{font-family:ui-monospace,Menlo,monospace;background:#eef0ff;padding:2px 6px;border-radius:5px;font-size:.85em}.prose pre code{background:none;padding:0;color:inherit}
.prose table{border-collapse:collapse;width:100%;margin:1.2em 0;display:block;overflow-x:auto}.prose th,.prose td{border-bottom:1px solid var(--line);padding:9px 12px;text-align:left}
.callout{border-left:3px solid var(--brand);background:#eef0ff;border-radius:0 10px 10px 0;padding:14px 18px;margin:1.3em 0;font-size:.95em}.callout.example{border-color:#12896f;background:#e3f5ef}.callout.summary{border-color:var(--gold);background:#fbf3dc}.callout.practice{border-color:#ea580c;background:#fff1e6}
.block-label{display:block;font-size:12px;font-weight:800;margin-bottom:5px;text-transform:uppercase;letter-spacing:.04em}
.actions{display:flex;gap:10px;flex-wrap:wrap;margin-top:26px;padding-top:20px;border-top:1px solid var(--line)}.actions .sp{margin-left:auto;display:flex;gap:10px}
.toast{position:fixed;bottom:26px;left:50%;transform:translateX(-50%);background:#152c69;color:#fff;padding:10px 18px;border-radius:10px;font-weight:600;font-size:14px;opacity:0;pointer-events:none;transition:opacity .3s;z-index:99}.toast.show{opacity:1}
/* quiz */
.q{border:1px solid var(--line);border-radius:12px;padding:18px 20px;margin-bottom:14px;background:#fff}.q b.n{color:var(--brand);font-size:12px}.q p.qt{font-weight:600;margin:4px 0 12px}
.opt{display:flex;gap:10px;padding:10px 12px;border:1px solid var(--line);border-radius:9px;margin-bottom:8px;cursor:pointer;font-size:14px}.opt:hover{background:#f9f9ff}.opt.right{background:var(--okbg);border-color:#bbf7d0}.opt.wrong{background:var(--errbg);border-color:#fecaca}
.expl{font-size:13.5px;color:var(--mute);margin-top:8px}
.score{font-size:2.6rem;font-weight:800}
/* community */
.thread{display:flex;gap:14px;padding:16px 4px;border-bottom:1px solid var(--line)}.thread:last-child{border:none}
.av{width:40px;height:40px;border-radius:50%;background:var(--grad);color:#fff;display:flex;align-items:center;justify-content:center;font-weight:800;flex:none}
.thread h3{font-size:15.5px;font-weight:700}.tmeta{font-size:12.5px;color:var(--mute);display:flex;gap:12px;flex-wrap:wrap;margin-top:3px}
.reply{display:flex;gap:14px;padding:18px 0;border-bottom:1px solid var(--line)}.reply.ans{background:var(--okbg);margin:0 -24px;padding:18px 24px}
.lk{background:none;border:1px solid var(--line);border-radius:99px;padding:4px 12px;font-size:12.5px;font-weight:600;color:var(--mute);cursor:pointer}.lk.on{color:var(--brand);border-color:var(--brand);background:#eef0ff}
.body{white-space:pre-wrap;word-wrap:break-word;margin-top:6px}
/* certificate */
.cert{width:100%;max-width:1000px;margin:0 auto;aspect-ratio:1.414/1;background:#fafaf5;border:3px solid #d4af37;outline:1px solid #4f46e5;outline-offset:-14px;position:relative;text-align:center;padding:5% 7%;display:flex;flex-direction:column;align-items:center;justify-content:center}
.cert::before{content:"DEGLECY";position:absolute;inset:0;display:flex;align-items:center;justify-content:center;font:800 11vw serif;color:rgba(79,70,229,.05);transform:rotate(-24deg);pointer-events:none}
.cert .br{font-weight:800;letter-spacing:.3em;font-size:1.1rem}.cert h1{font:700 clamp(1.4rem,4.4vw,3rem) Georgia,serif;margin:10px 0 4px}.cert .bar2{height:5px;width:100%;background:var(--grad);margin:8px 0 14px}
.cert .nm{font:700 clamp(1.6rem,5vw,3.4rem) Georgia,serif;color:#b48c28;border-bottom:2px solid #d4af37;padding:0 30px 4px;margin:8px 0}.cert .cn{font-weight:800;font-size:clamp(1rem,2.6vw,1.8rem);text-transform:uppercase;margin:8px 0}
.cert .ft{position:absolute;left:7%;right:7%;bottom:6%;display:flex;justify-content:space-between;align-items:flex-end;font-size:clamp(9px,1.3vw,13px);text-align:left}.cert .ft img{width:clamp(60px,10vw,110px)}
.cert .sig{text-align:center;border-top:1px solid #999;padding-top:4px;min-width:150px}
@media print{@page{size:landscape;margin:0}.nav,.noprint,.toast{display:none!important}body{background:#fff}.wrap{padding:0;max-width:none}.cert{max-width:none;border-width:4px;-webkit-print-color-adjust:exact;print-color-adjust:exact}}