:root{--brand:#0056d2;--brand2:#003e9c;--navy:#0b1f44;--ink:#1f2937;--mut:#5b6677;--line:#e3e8ef;--soft:#f4f7fc;--card:#fff;--ok:#0f9d58;--amber:#b45309;--r:14px;--sh:0 1px 2px rgba(15,31,68,.06),0 8px 24px -12px rgba(15,31,68,.18)}
*{box-sizing:border-box}html{scroll-behavior:smooth}
body{margin:0;font:16px/1.65 Inter,system-ui,-apple-system,"Segoe UI",Roboto,sans-serif;color:var(--ink);background:#fff;-webkit-font-smoothing:antialiased}
a{color:var(--brand);text-decoration:none}a:hover{text-decoration:underline}
h1,h2,h3{color:var(--navy);line-height:1.2;margin:0 0 .5em;letter-spacing:-.02em}
img,svg{max-width:100%}.wrap{max-width:1180px;margin:0 auto;padding:0 22px}
:focus-visible{outline:3px solid #7aa7ff;outline-offset:2px;border-radius:6px}
.skip{position:absolute;left:-999px}.skip:focus{left:10px;top:10px;background:#fff;padding:8px 12px;z-index:99}
/* header */
.hdr{position:sticky;top:0;z-index:50;background:rgba(255,255,255,.92);backdrop-filter:saturate(1.4) blur(10px);border-bottom:1px solid var(--line)}
.hdr .wrap{display:flex;align-items:center;gap:18px;height:68px}
.logo{display:flex;align-items:center;gap:11px;color:var(--navy);font-weight:800;letter-spacing:-.02em;font-size:1.05rem}.logo:hover{text-decoration:none}
.mark{width:38px;height:38px;border-radius:10px;background:linear-gradient(135deg,#0056d2,#00a6ff);color:#fff;display:grid;place-items:center;font-weight:800;font-size:.95rem}
.logo small{display:block;font-weight:500;color:var(--mut);font-size:.72rem;letter-spacing:0;margin-top:-2px}
.nav{margin-left:auto;display:flex;gap:4px}.nav a{padding:8px 14px;border-radius:9px;color:#334155;font-weight:600;font-size:.95rem}
.nav a:hover{background:var(--soft);text-decoration:none;color:var(--brand)}.nav a.on{color:var(--brand);background:#eaf1ff}
.burger{display:none;margin-left:auto;border:1px solid var(--line);background:#fff;border-radius:10px;width:42px;height:42px;font-size:1.3rem;cursor:pointer}
@media(max-width:860px){.burger{display:block}.nav{display:none;position:absolute;top:68px;left:0;right:0;background:#fff;border-bottom:1px solid var(--line);flex-direction:column;padding:10px 16px 16px}.nav.open{display:flex}.nav a{padding:12px 10px}}
/* buttons */
.btn{display:inline-flex;align-items:center;gap:8px;border:1.5px solid var(--brand);background:var(--brand);color:#fff;font:600 .98rem Inter,system-ui,sans-serif;padding:11px 20px;border-radius:10px;cursor:pointer;transition:.15s}
.btn:hover{background:var(--brand2);border-color:var(--brand2);text-decoration:none;transform:translateY(-1px)}
.btn.ghost{background:#fff;color:var(--brand)}.btn.ghost:hover{background:#eaf1ff}.btn.sm{padding:7px 14px;font-size:.88rem}
/* hero */
.hero{background:radial-gradient(900px 420px at 85% -10%,#dbe9ff 0,transparent 60%),linear-gradient(180deg,#f6f9ff,#fff);border-bottom:1px solid var(--line)}
.hero .wrap{display:grid;grid-template-columns:1.1fr .9fr;gap:40px;align-items:center;padding-top:70px;padding-bottom:70px}
.eyebrow{display:inline-block;background:#eaf1ff;color:var(--brand);font-weight:700;font-size:.8rem;padding:5px 12px;border-radius:99px;letter-spacing:.02em;margin-bottom:16px}
.hero h1{font-size:clamp(2.1rem,4.6vw,3.4rem);font-weight:800}.hero h1 em{font-style:normal;color:var(--brand)}
.hero p.lead{font-size:1.15rem;color:var(--mut);max-width:56ch;margin:0 0 26px}.cta{display:flex;gap:12px;flex-wrap:wrap}
.vis{position:relative;min-height:340px}.vc{position:absolute;background:#fff;border:1px solid var(--line);border-radius:16px;box-shadow:var(--sh);padding:16px 18px}
.vc.a{top:0;left:6%;right:14%}.vc.b{top:120px;right:0;left:34%}.vc.c{bottom:0;left:0;right:30%}
.vc h4{margin:0 0 6px;font-size:.95rem;color:var(--navy)}.vc small{color:var(--mut)}
.steps4{display:flex;gap:6px;flex-wrap:wrap;margin-top:8px}.steps4 span{font-size:.78rem;font-weight:700;padding:3px 10px;border-radius:99px;background:#eaf1ff;color:var(--brand)}
.vc pre{margin:8px 0 0;background:#0b1f44;color:#d6e6ff;padding:10px;border-radius:10px;font:12px/1.5 "JetBrains Mono",Consolas,monospace;overflow:hidden}
.mini-bar{height:8px;background:#e6ecf5;border-radius:9px;overflow:hidden;margin-top:8px}.mini-bar i{display:block;height:100%;background:linear-gradient(90deg,#0056d2,#00a6ff)}
@media(max-width:900px){.hero .wrap{grid-template-columns:1fr;padding-top:44px;padding-bottom:44px}.vis{display:none}}
/* stats */
.stats{display:grid;grid-template-columns:repeat(4,1fr);gap:0;border:1px solid var(--line);border-radius:var(--r);margin:-34px auto 0;position:relative;background:#fff;box-shadow:var(--sh)}
.stats div{padding:20px 22px;border-right:1px solid var(--line)}.stats div:last-child{border:0}.stats b{display:block;font-size:1.7rem;color:var(--navy);letter-spacing:-.02em}.stats span{color:var(--mut);font-size:.9rem}
@media(max-width:760px){.stats{grid-template-columns:1fr 1fr}.stats div:nth-child(2){border-right:0}.stats div:nth-child(-n+2){border-bottom:1px solid var(--line)}}
/* sections */
.sec{padding:64px 0}.sec.alt{background:var(--soft)}.sec h2{font-size:clamp(1.6rem,3vw,2.1rem)}
.sh{display:flex;align-items:end;justify-content:space-between;gap:16px;margin-bottom:26px;flex-wrap:wrap}.sh p{margin:0;color:var(--mut);max-width:60ch}
.grid3{display:grid;grid-template-columns:repeat(auto-fill,minmax(300px,1fr));gap:22px}
.card{background:var(--card);border:1px solid var(--line);border-radius:var(--r);box-shadow:var(--sh);overflow:hidden;display:flex;flex-direction:column;color:var(--ink);transition:.18s}
a.card:hover{transform:translateY(-4px);text-decoration:none;box-shadow:0 18px 40px -18px rgba(0,60,160,.45)}
.cover{height:132px;display:flex;align-items:center;justify-content:space-between;padding:0 22px;background:linear-gradient(135deg,var(--g1),var(--g2));color:#fff}
.cover .em{font-size:3rem;filter:drop-shadow(0 4px 8px rgba(0,0,0,.25))}.cover .lbl{font-weight:800;font-size:1.05rem;text-align:right;max-width:55%;line-height:1.2;text-shadow:0 2px 8px rgba(0,0,0,.25)}
.card .bd{padding:18px 20px 8px;flex:1}.card .bd h3{font-size:1.12rem;margin:6px 0}.card .bd p{margin:0 0 10px;color:var(--mut);font-size:.93rem}
.tag{font-size:.74rem;font-weight:700;color:var(--brand);text-transform:uppercase;letter-spacing:.06em}
.meta{display:flex;gap:6px 14px;flex-wrap:wrap;list-style:none;padding:0;margin:8px 0 0;color:var(--mut);font-size:.85rem}
.card .ft{display:flex;justify-content:space-between;align-items:center;padding:12px 20px 16px;border-top:1px solid var(--line);margin-top:10px;font-size:.9rem;font-weight:600}
.badge{padding:3px 10px;border-radius:99px;font-size:.75rem;font-weight:700}.badge.ok{background:#e3f6ec;color:var(--ok)}.badge.soon{background:#fff3e0;color:var(--amber)}
.prog{height:6px;background:#e6ecf5;border-radius:9px;overflow:hidden;margin:10px 0 2px}.prog i{display:block;height:100%;background:var(--ok)}
.feat{display:grid;grid-template-columns:repeat(auto-fit,minmax(230px,1fr));gap:18px}.feat .f{background:#fff;border:1px solid var(--line);border-radius:var(--r);padding:20px}
.feat .n{width:42px;height:42px;border-radius:12px;background:#eaf1ff;color:var(--brand);display:grid;place-items:center;font-size:1.3rem;margin-bottom:10px}.feat h3{font-size:1.05rem}.feat p{margin:0;color:var(--mut);font-size:.92rem}
.band{background:linear-gradient(135deg,#0b1f44,#0b3d91);color:#fff;border-radius:20px;padding:40px;display:flex;justify-content:space-between;align-items:center;gap:20px;flex-wrap:wrap}.band h2{color:#fff;margin:0 0 6px}.band p{margin:0;color:#c9dbff}
.band .btn{background:#fff;color:var(--brand);border-color:#fff}
/* page head */
.ph{background:linear-gradient(180deg,#f6f9ff,#fff);border-bottom:1px solid var(--line);padding:46px 0 34px}.ph h1{font-size:clamp(1.9rem,4vw,2.6rem);margin-bottom:8px}.ph p{color:var(--mut);max-width:70ch;margin:0}
.crumb{font-size:.85rem;color:var(--mut);margin-bottom:10px}
.chips{display:flex;flex-wrap:wrap;gap:8px;margin:14px 0 0}.chip{border:1px solid var(--line);background:#fff;border-radius:99px;padding:5px 14px;font-size:.86rem;color:#334155;font-weight:600}
button.chip{cursor:pointer;font-family:inherit}button.chip.on{background:var(--brand);border-color:var(--brand);color:#fff}
input.s{font:inherit;border:1.5px solid var(--line);border-radius:10px;padding:9px 14px;min-width:240px;background:#fff}
.tools{display:flex;gap:10px;flex-wrap:wrap;align-items:center;margin:0 0 22px}
/* publications */
.yr{font-weight:800;color:var(--brand);margin:26px 0 10px;font-size:1.15rem;border-bottom:2px solid #eaf1ff;padding-bottom:6px}
.pub{background:#fff;border:1px solid var(--line);border-radius:var(--r);padding:18px 20px;margin-bottom:12px;box-shadow:var(--sh)}
.pub h3{font-size:1.06rem;margin:6px 0 4px}.pub .au{color:#334155;font-size:.93rem}.pub .au b{color:var(--navy)}.pub .vn{color:var(--mut);font-size:.9rem;font-style:italic}.pub p{margin:8px 0 0;color:#475569;font-size:.93rem}
.pub .lk{display:flex;gap:8px;flex-wrap:wrap;margin-top:10px}
.notice{background:#fff8e6;border:1px solid #f4dba0;color:#7a5b00;border-radius:12px;padding:12px 16px;font-size:.92rem;margin-bottom:22px}
/* about */
.about{display:grid;grid-template-columns:300px 1fr;gap:44px;align-items:start}
.avatar{width:100%;aspect-ratio:1;border-radius:24px;background:linear-gradient(135deg,#0056d2,#00a6ff);display:grid;place-items:center;color:#fff;font-size:5rem;font-weight:800;box-shadow:var(--sh)}
.side .btn{width:100%;justify-content:center;margin-top:10px}.about h2{margin-top:30px}.about p{color:#334155}
.list{padding-left:18px;color:#334155}.list li{margin:6px 0}
@media(max-width:820px){.about{grid-template-columns:1fr}.avatar{max-width:220px;font-size:3.6rem}}
/* video */
.video{position:relative;padding-top:56.25%;border-radius:16px;overflow:hidden;border:1px solid var(--line);box-shadow:var(--sh);background:#0b1f44}.video iframe{position:absolute;inset:0;width:100%;height:100%;border:0}
.two{display:grid;grid-template-columns:1.6fr 1fr;gap:28px;align-items:start}@media(max-width:900px){.two{grid-template-columns:1fr}}
/* footer */
.ftr{background:#0b1f44;color:#c9dbff;margin-top:0;padding:46px 0 26px}.ftr a{color:#c9dbff}.ftr h4{color:#fff;margin:0 0 10px;font-size:.95rem}
.fg{display:grid;grid-template-columns:1.4fr 1fr 1fr 1fr;gap:28px}.fg ul{list-style:none;margin:0;padding:0}.fg li{margin:6px 0;font-size:.92rem}
.copy{border-top:1px solid #213866;margin-top:28px;padding-top:16px;font-size:.84rem;color:#9bb4e6}
@media(max-width:760px){.fg{grid-template-columns:1fr 1fr}}
.empty{border:2px dashed var(--line);border-radius:var(--r);padding:30px;text-align:center;color:var(--mut)}
@media(prefers-reduced-motion:reduce){*{transition:none!important;scroll-behavior:auto!important}}
/* ---- refinements: Coursera/Udemy-like scale ---- */
.hero h1{font-size:clamp(2rem,4vw,3rem);letter-spacing:-.025em}
.hero p.lead{font-size:1.125rem;margin-bottom:22px}
.hsearch{display:flex;max-width:560px;margin:0 0 14px;background:#fff;border:1px solid #c5d0e0;border-radius:12px;padding:5px;box-shadow:var(--sh)}
.hsearch input{flex:1;min-width:0;border:0;outline:0;font:inherit;padding:10px 14px;background:transparent;color:var(--ink)}
.hsearch .btn{padding:10px 22px}
.topics{display:flex;flex-wrap:wrap;gap:8px 14px;align-items:center;margin:0 0 26px;font-size:.92rem;color:var(--mut)}.topics a{font-weight:600}
.sec h2{font-size:1.75rem}.sh p{color:var(--mut);margin:0}
.card{transition:box-shadow .2s,transform .2s}.card:hover{box-shadow:0 12px 30px -14px rgba(15,31,68,.35);transform:translateY(-2px)}
body{font-size:16px;line-height:1.6}
.hero h1{font-size:clamp(2.3rem,5vw,3.6rem);line-height:1.08}
.vis{display:flex;flex-direction:column;gap:14px;align-items:stretch;max-width:420px;justify-self:end;width:100%;position:static;height:auto}
.vis .def{background:#fff;border:1px solid var(--line);border-radius:16px;padding:20px 22px;box-shadow:var(--sh);position:static;transform:none;width:auto}
.vis .def small{color:var(--brand);font-weight:800;letter-spacing:.12em;font-size:.72rem}.vis .def b{display:block;font-size:1.25rem;color:var(--navy);margin:2px 0 4px}.vis .def p{margin:0;color:var(--mut);font-size:.95rem}
.vis .def.d2{background:linear-gradient(135deg,#0056d2,#0a7cff);border:0}.vis .def.d2 small,.vis .def.d2 b,.vis .def.d2 p{color:#fff}.vis .def.d2 p{opacity:.9}
.path{list-style:none;margin:0;padding:0 8px;display:grid;gap:0;position:relative}
.path li{display:flex;align-items:center;gap:12px;padding:7px 0;font-weight:600;color:var(--navy);position:relative}
.path li span{width:28px;height:28px;border-radius:50%;background:#eaf1ff;color:var(--brand);display:grid;place-items:center;font-size:.85rem;font-weight:800;z-index:1}
.path li:not(:last-child):after{content:"";position:absolute;left:13px;top:34px;height:calc(100% - 14px);border-left:2px dashed #b7cdf5}
.vis{min-height:0}