*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth;font-size:16px}
:root{
  --ink:#05091a;--ink2:#0a1230;--ink3:#101c3d;
  --glass:rgba(255,255,255,.03);--rim:rgba(255,255,255,.08);--rim2:rgba(255,255,255,.15);
  --txt:#eef3ff;--txt2:#8ca8d8;--txt3:#4a68a0;--txt4:#1e3260;
  --acc:#a78bfa;--acc2:#c4b5fd;--acc3:#7c3aed;
  --teal:#2de8c0;--amber:#fbbf24;--green:#4ade80;--red:#f87171;--purple:#a78bfa;
  --grd-acc:linear-gradient(135deg,#a78bfa,#7c3aed);
  --grd-teal:linear-gradient(135deg,#2de8c0,#0d9488);
  --sh1:0 4px 20px rgba(0,0,0,.3);--sh2:0 8px 40px rgba(0,0,0,.5);
  --r:12px;--rfull:9999px;
  --ff-d:'Syne',sans-serif;--ff-b:'DM Sans',sans-serif;--ff-m:'JetBrains Mono',monospace;
}
body{background:var(--ink);color:var(--txt);font-family:var(--ff-b);min-height:100vh;overflow-x:hidden;line-height:1.65;-webkit-font-smoothing:antialiased}
a{text-decoration:none;color:inherit}
button{font-family:var(--ff-b);cursor:pointer}
.bg-mesh{position:fixed;inset:0;z-index:0;pointer-events:none;background:radial-gradient(ellipse 90% 60% at 50% -10%,rgba(167,139,250,.12) 0%,transparent 55%),radial-gradient(ellipse 50% 50% at 100% 85%,rgba(45,232,192,.07) 0%,transparent 50%)}
.bg-grid{position:fixed;inset:0;z-index:0;pointer-events:none;opacity:.018;background-image:linear-gradient(rgba(167,139,250,.6) 1px,transparent 1px),linear-gradient(90deg,rgba(167,139,250,.6) 1px,transparent 1px);background-size:60px 60px}
.page{position:relative;z-index:1}
nav{position:sticky;top:0;z-index:600;display:flex;align-items:center;justify-content:space-between;padding:.85rem 2.5rem;background:rgba(5,9,26,.92);backdrop-filter:blur(28px) saturate(160%);border-bottom:1px solid var(--rim)}
.nav-logo{display:flex;align-items:center;gap:12px;cursor:pointer}
.nav-name{font-family:var(--ff-d);font-weight:800;font-size:1rem;letter-spacing:-.02em}
.btn-st{padding:8px 20px;border-radius:var(--rfull);background:var(--grd-acc);color:#fff;border:none;font-family:var(--ff-d);font-weight:700;font-size:.8rem;transition:.18s;box-shadow:0 4px 18px rgba(167,139,250,.35)}
.btn-st:hover{opacity:.88;transform:translateY(-1px)}
.back-btn{display:inline-flex;align-items:center;gap:7px;padding:7px 16px;border-radius:var(--rfull);border:1px solid var(--rim);background:var(--glass);color:var(--txt2);font-size:.78rem;font-weight:600;transition:.18s}
.back-btn:hover{border-color:var(--rim2);color:var(--txt)}
.nav-right{display:flex;align-items:center;gap:9px}
.flying-logo-wrap{display:flex;align-items:center;flex-shrink:0}
.flying-logo{width:52px;height:36px;object-fit:contain;display:block;animation:logoFloat 3.6s ease-in-out infinite;filter:drop-shadow(0 5px 12px rgba(167,139,250,.4))}
@keyframes logoFloat{0%,100%{transform:translateY(0)}25%{transform:translateY(-7px) rotate(.6deg)}50%{transform:translateY(-2px) rotate(-.3deg)}75%{transform:translateY(-8px) rotate(.4deg)}}
.lesson-wrap{max-width:1120px;margin:0 auto;padding:3rem 2.5rem 6rem;display:grid;grid-template-columns:1fr 300px;gap:2.5rem;align-items:start}
.lesson-header{margin-bottom:2.5rem}
.breadcrumb{display:flex;align-items:center;gap:8px;font-size:.72rem;color:var(--txt3);margin-bottom:1.2rem;flex-wrap:wrap}
.breadcrumb span{color:var(--txt4)}
.lesson-eyebrow{display:flex;align-items:center;gap:10px;margin-bottom:1rem;flex-wrap:wrap}
.phase-badge{font-size:.62rem;font-weight:700;padding:3px 10px;border-radius:var(--rfull);background:rgba(45,232,192,.12);color:var(--teal);border:1px solid rgba(45,232,192,.2);letter-spacing:.06em}
.diff-badge{font-size:.62rem;font-weight:700;padding:3px 10px;border-radius:var(--rfull);background:rgba(167,139,250,.12);color:var(--acc2);border:1px solid rgba(167,139,250,.2)}
.mod-badge{font-size:.62rem;font-weight:600;padding:3px 10px;border-radius:var(--rfull);background:var(--glass);border:1px solid var(--rim);color:var(--txt3);font-family:var(--ff-m)}
.lesson-title{font-family:var(--ff-d);font-size:clamp(2rem,4vw,3rem);font-weight:800;line-height:1.05;letter-spacing:-.025em;margin-bottom:.9rem}
.lesson-title .hl{background:linear-gradient(135deg,#a78bfa,#2de8c0);-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}
.lesson-meta-row{display:flex;align-items:center;gap:20px;flex-wrap:wrap;font-size:.78rem;color:var(--txt3)}
.lm-item{display:flex;align-items:center;gap:6px}
.lesson-intro{font-size:1.05rem;color:var(--txt2);line-height:1.8;margin-bottom:2.5rem;padding:1.4rem 1.6rem;background:var(--ink2);border:1px solid var(--rim);border-left:3px solid var(--acc);border-radius:0 var(--r) var(--r) 0}
.lesson-intro h3{font-family:var(--ff-d);font-size:1.1rem;color:var(--txt);margin-bottom:.5rem}
.content-block{margin-bottom:2.8rem}
.section-label{display:inline-flex;align-items:center;gap:8px;font-size:.68rem;font-weight:700;letter-spacing:.1em;text-transform:uppercase;color:var(--teal);margin-bottom:.9rem}
.section-label::before{content:'';width:16px;height:2px;background:var(--grd-teal);border-radius:2px}
h2.ch{font-family:var(--ff-d);font-size:1.55rem;font-weight:800;letter-spacing:-.02em;margin-bottom:.8rem;line-height:1.2}
h3.ch3{font-family:var(--ff-d);font-size:1.05rem;font-weight:700;margin:1.4rem 0 .6rem;color:var(--acc2)}
p.cp{color:var(--txt2);line-height:1.82;margin-bottom:1rem;font-size:.97rem}
ul.notes-list{color:var(--txt2);line-height:1.8;margin:0 0 1rem 1.2rem;font-size:.93rem}
ul.notes-list li{margin-bottom:.35rem}
ul.notes-list strong{color:var(--txt)}
code{font-family:var(--ff-m);font-size:.84em;padding:2px 7px;border-radius:5px;background:rgba(167,139,250,.1);color:var(--acc2);border:1px solid rgba(167,139,250,.15)}
.hbox{border-radius:var(--r);padding:1.3rem 1.5rem;margin-bottom:1.4rem;display:flex;gap:13px;align-items:flex-start}
.hbox.info{background:rgba(167,139,250,.07);border:1px solid rgba(167,139,250,.18)}
.hbox.tip{background:rgba(45,232,192,.07);border:1px solid rgba(45,232,192,.18)}
.hbox.warn{background:rgba(251,191,36,.07);border:1px solid rgba(251,191,36,.18)}
.hbox-ic{font-size:1.2rem;flex-shrink:0;margin-top:2px}
.hbox-t{font-family:var(--ff-d);font-weight:700;font-size:.85rem;margin-bottom:.3rem}
.hbox.info .hbox-t{color:var(--acc2)}
.hbox.tip .hbox-t{color:var(--teal)}
.hbox.warn .hbox-t{color:var(--amber)}
.hbox-s{font-size:.83rem;color:var(--txt2);line-height:1.7}
.stat-row{display:grid;grid-template-columns:repeat(4,1fr);gap:10px;margin:1.3rem 0}
.stat-card{background:var(--ink2);border:1px solid var(--rim);border-radius:11px;padding:1rem .8rem;text-align:center}
.stat-num{font-family:var(--ff-d);font-size:1.3rem;font-weight:800;color:var(--acc2)}
.stat-lbl{font-size:.68rem;color:var(--txt3);margin-top:.2rem}
.steps{display:flex;flex-direction:column;gap:0;position:relative;padding-left:2.2rem;margin-bottom:1.5rem}
.steps::before{content:'';position:absolute;left:11px;top:20px;bottom:20px;width:2px;background:linear-gradient(to bottom,var(--acc),var(--teal));border-radius:2px}
.step{position:relative;padding:.9rem 0 .9rem 1.2rem;margin-bottom:.2rem}
.step-dot{position:absolute;left:-2.2rem;top:50%;transform:translateY(-50%);width:24px;height:24px;border-radius:50%;background:var(--grd-acc);display:flex;align-items:center;justify-content:center;font-size:.62rem;font-weight:800;font-family:var(--ff-d);color:#fff;flex-shrink:0}
.step-t{font-family:var(--ff-d);font-size:.9rem;font-weight:700;margin-bottom:.25rem}
.step-s{font-size:.82rem;color:var(--txt2);line-height:1.65}
.facts-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:12px;margin-bottom:1.5rem}
.fact{background:var(--ink2);border:1px solid var(--rim);border-radius:12px;padding:1rem 1.1rem;transition:.2s}
.fact:hover{border-color:var(--rim2);transform:translateY(-2px)}
.fact-ic{font-size:1.4rem;margin-bottom:.5rem}
.fact-t{font-family:var(--ff-d);font-size:.85rem;font-weight:800;margin-bottom:.2rem}
.fact-s{font-size:.75rem;color:var(--txt2);line-height:1.55}
.uses-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:10px;margin-bottom:1.5rem}
.use-card{background:var(--ink2);border:1px solid var(--rim);border-radius:11px;padding:.9rem;text-align:center;transition:.2s}
.use-card:hover{border-color:var(--rim2);transform:translateY(-2px);box-shadow:var(--sh1)}
.use-ic{font-size:1.6rem;margin-bottom:.4rem}
.use-t{font-family:var(--ff-d);font-size:.78rem;font-weight:800;margin-bottom:.2rem}
.use-s{font-size:.68rem;color:var(--txt3);line-height:1.4}
.companies{display:flex;flex-wrap:wrap;gap:9px;margin-bottom:1.5rem}
.comp-tag{padding:5px 14px;border-radius:var(--rfull);background:var(--ink2);border:1px solid var(--rim);font-size:.75rem;font-weight:600;color:var(--txt2);transition:.18s}
.comp-tag:hover{border-color:var(--acc);color:var(--acc2)}
.vis-barchart{margin:1.8rem 0;background:var(--ink2);border:1px solid var(--rim);border-radius:var(--r);padding:1.4rem 1.6rem}
.vbc-title{font-family:var(--ff-d);font-size:.85rem;font-weight:700;color:var(--txt);margin-bottom:1rem}
.vbc-row{display:flex;align-items:center;gap:.9rem;margin-bottom:.65rem}
.vbc-lbl{width:130px;font-size:.76rem;color:var(--txt2);text-align:right;flex-shrink:0;line-height:1.3}
.vbc-track{flex:1;height:28px;background:var(--ink3);border-radius:6px;overflow:hidden}
.vbc-bar{height:100%;border-radius:6px;display:flex;align-items:center;padding-left:.7rem;font-size:.7rem;font-weight:700;color:#fff;min-width:32px}
.vbc-pct{font-family:var(--ff-m);font-size:.72rem;color:var(--txt3);width:38px;flex-shrink:0}
.vis-stats{display:grid;grid-template-columns:repeat(auto-fit,minmax(120px,1fr));gap:.9rem;margin:1.5rem 0}
.vs-card{background:var(--ink2);border:1px solid var(--rim);border-radius:var(--r);padding:1.1rem;text-align:center}
.vs-num{font-family:var(--ff-d);font-size:2rem;font-weight:800;background:var(--grd-acc);-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text;line-height:1.1}
.vs-lbl{font-size:.72rem;color:var(--txt3);margin-top:.3rem;line-height:1.4}
.vis-timeline{margin:1.5rem 0;padding-left:1.6rem;border-left:2px solid var(--rim2)}
.vt-item{position:relative;padding:.6rem 0 .7rem 1.2rem;margin-bottom:.1rem}
.vt-item::before{content:'';position:absolute;left:-5.5px;top:.85rem;width:9px;height:9px;border-radius:50%;background:var(--acc);border:2px solid var(--ink)}
.vt-year{font-family:var(--ff-m);font-size:.65rem;color:var(--acc2);margin-bottom:.15rem;letter-spacing:.04em}
.vt-body{font-size:.82rem;color:var(--txt2);line-height:1.55}
.vt-body strong{color:var(--txt)}
@media(max-width:900px){.facts-grid{grid-template-columns:1fr}.uses-grid{grid-template-columns:repeat(2,1fr)}}
@media(max-width:600px){.uses-grid{grid-template-columns:1fr}.facts-grid{grid-template-columns:1fr}}
.code-wrap{margin:1.4rem 0;border-radius:var(--r);overflow:hidden;border:1px solid var(--rim2);box-shadow:var(--sh1)}
.code-header{display:flex;align-items:center;justify-content:space-between;padding:.55rem 1rem;background:#0d1a3a;border-bottom:1px solid var(--rim)}
.code-title{font-family:var(--ff-m);font-size:.68rem;color:var(--txt3)}
.code-lang{padding:2px 8px;border-radius:var(--rfull);background:rgba(167,139,250,.15);color:var(--acc2);font-size:.6rem;font-weight:700;letter-spacing:.05em}
pre{background:#070e24;padding:1.4rem 1.2rem;margin:0;overflow-x:auto;font-family:var(--ff-m);font-size:.87rem;line-height:1.7;white-space:pre-wrap}
/* QUIZ */
.quiz-sec{background:var(--ink2);border:1px solid var(--rim);border-radius:18px;padding:2rem;margin-bottom:2.8rem}
.quiz-title{font-family:var(--ff-d);font-size:1.2rem;font-weight:800;margin-bottom:.3rem}
.quiz-sub{font-size:.82rem;color:var(--txt3);margin-bottom:1.6rem}
.q-item{margin-bottom:1.5rem}
.q-text{font-size:.9rem;font-weight:600;margin-bottom:.7rem;color:var(--txt)}
.q-opts{display:flex;flex-direction:column;gap:7px}
.q-opt{padding:.7rem 1rem;border-radius:9px;border:1px solid var(--rim);background:var(--glass);font-size:.82rem;color:var(--txt2);cursor:pointer;transition:.18s;text-align:left;display:flex;align-items:center;gap:10px}
.q-opt:hover{border-color:var(--rim2);color:var(--txt)}
.q-opt.correct{border-color:var(--teal);background:rgba(45,232,192,.1);color:var(--teal)}
.q-opt.wrong{border-color:var(--red);background:rgba(248,113,113,.08);color:var(--red)}
.q-opt.disabled{cursor:default;pointer-events:none}
.q-radio{width:16px;height:16px;border-radius:50%;border:2px solid var(--rim2);flex-shrink:0;display:flex;align-items:center;justify-content:center;transition:.18s}
.q-opt.correct .q-radio{border-color:var(--teal);background:var(--teal)}
.q-opt.wrong .q-radio{border-color:var(--red)}
.q-opt.correct .q-radio::after,.q-opt.wrong .q-radio::after{content:'';width:7px;height:7px;border-radius:50%;background:#fff}
.q-feedback{font-size:.78rem;margin-top:.5rem;padding:.5rem .8rem;border-radius:7px;display:none;line-height:1.55}
.q-feedback.show{display:block}
.q-feedback.ok{background:rgba(45,232,192,.08);color:var(--teal);border:1px solid rgba(45,232,192,.2)}
.q-feedback.bad{background:rgba(248,113,113,.08);color:var(--red);border:1px solid rgba(248,113,113,.2)}
.quiz-result{background:var(--ink);border:1px solid var(--rim2);border-radius:12px;padding:1.2rem;text-align:center;display:none;margin-top:1.2rem}
.quiz-result.show{display:block}
.qr-ic{font-size:2rem;margin-bottom:.4rem}
.qr-t{font-family:var(--ff-d);font-weight:800;font-size:1rem;margin-bottom:.2rem}
.qr-s{font-size:.8rem;color:var(--txt2)}
/* SIDEBAR */
.sidebar-card{background:var(--ink2);border:1px solid var(--rim);border-radius:14px;padding:1.3rem;margin-bottom:14px}
.sc-t{font-family:var(--ff-d);font-size:.85rem;font-weight:800;margin-bottom:1rem;display:flex;align-items:center;gap:8px}
.sl-item{display:flex;align-items:center;gap:10px;padding:.55rem .7rem;border-radius:8px;font-size:.78rem;transition:.15s;cursor:pointer;border:1px solid transparent}
.sl-item:hover{background:var(--glass);border-color:var(--rim)}
.sl-item.active{background:rgba(167,139,250,.1);border-color:rgba(167,139,250,.25);color:var(--acc2)}
.sl-num{width:22px;height:22px;border-radius:6px;background:var(--ink3);display:flex;align-items:center;justify-content:center;font-size:.6rem;font-weight:700;font-family:var(--ff-m);flex-shrink:0}
.sl-item.active .sl-num{background:var(--grd-acc);color:#fff}
.sl-name{flex:1;line-height:1.3}
.lesson-nav{display:flex;justify-content:space-between;align-items:center;margin-top:3rem;padding-top:2rem;border-top:1px solid var(--rim)}
.ln-btn{display:flex;align-items:center;gap:9px;padding:.9rem 1.5rem;border-radius:14px;border:1px solid var(--rim);background:var(--glass);color:var(--txt2);font-size:.85rem;font-weight:600;transition:.22s;cursor:pointer}
.ln-btn:hover{border-color:var(--rim2);color:var(--txt);transform:translateY(-2px)}
.ln-btn.next{background:var(--grd-acc);border-color:transparent;color:#fff;box-shadow:0 6px 24px rgba(167,139,250,.35)}
.rv{opacity:0;transform:translateY(22px);transition:opacity .55s ease,transform .55s ease}
@keyframes fadeUp{from{opacity:0;transform:translateY(20px)}to{opacity:1;transform:translateY(0)}}
.ani{animation:fadeUp .6s ease forwards}
#btt{position:fixed;bottom:2rem;right:2rem;width:42px;height:42px;border-radius:50%;background:var(--grd-acc);border:none;color:#fff;font-size:1rem;cursor:pointer;opacity:0;transform:translateY(10px);transition:.25s;z-index:500;box-shadow:var(--sh2)}
#btt.show{opacity:1;transform:translateY(0)}
@media(max-width:900px){.lesson-wrap{grid-template-columns:1fr;padding:2rem 1.5rem 5rem}.lesson-sidebar{position:static;display:none}.stat-row{grid-template-columns:repeat(2,1fr)}}
@media(max-width:600px){nav{padding:.85rem 1.2rem}.lesson-wrap{padding:1.5rem 1rem 4rem}.lesson-title{font-size:1.8rem}}