:root{
  --bg:#07090f; --bg2:#0d1119; --card:#111726; --card2:#161d2e;
  --border:#232c3f; --text:#e9edf5; --muted:#98a3b8;
  --accent:#ff6a00; --accent2:#ff9a3d; --accent-soft:rgba(255,106,0,.14);
  --blue:#2f6df6; --green:#2fd97a; --amber:#ffb020;
  --radius:16px; --maxw:1160px;
  --ease:cubic-bezier(.16,1,.3,1);
}
*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{
  font-family:'Inter',system-ui,-apple-system,Segoe UI,Roboto,sans-serif;
  background:var(--bg); color:var(--text); line-height:1.6;
  -webkit-font-smoothing:antialiased; overflow-x:hidden;
}
a{color:inherit;text-decoration:none}
.skip{position:absolute;left:-9999px;top:0;background:var(--accent);color:#000;padding:10px 16px;border-radius:0 0 8px 0;z-index:200}
.skip:focus{left:0}
.wrap{max-width:var(--maxw);margin:0 auto;padding:0 24px}

/* header */
.site-header{position:sticky;top:0;z-index:100;backdrop-filter:blur(14px);background:rgba(7,9,15,.72);border-bottom:1px solid var(--border)}
.nav-inner{max-width:var(--maxw);margin:0 auto;padding:14px 24px;display:flex;align-items:center;gap:28px}
.brand{display:flex;align-items:center;gap:10px;font-weight:800;font-size:1.15rem;letter-spacing:-.02em}
.brand-mark{display:grid;place-items:center;width:34px;height:34px;border-radius:10px;background:linear-gradient(135deg,var(--accent),var(--accent2));color:#000;font-size:1.05rem}
.nav-links{display:flex;gap:24px;margin-left:auto;font-size:.95rem}
.nav-links a{color:var(--muted);transition:color .2s}
.nav-links a:hover{color:var(--text)}
.nav-cta{margin-left:8px}
.burger{display:none;background:none;border:0;cursor:pointer;width:40px;height:40px;flex-direction:column;align-items:center;justify-content:center;gap:5px}
.burger span{display:block;width:22px;height:2px;background:var(--text);border-radius:2px;transition:.3s var(--ease)}
.burger[aria-expanded="true"] span:nth-child(1){transform:translateY(7px) rotate(45deg)}
.burger[aria-expanded="true"] span:nth-child(2){opacity:0}
.burger[aria-expanded="true"] span:nth-child(3){transform:translateY(-7px) rotate(-45deg)}

/* buttons */
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;padding:13px 24px;border-radius:12px;font-weight:600;font-size:.98rem;transition:.25s var(--ease);border:1px solid transparent;cursor:pointer}
.btn-primary{background:linear-gradient(135deg,var(--accent),var(--accent2));color:#0b0b0b;box-shadow:0 8px 30px -8px rgba(255,106,0,.5)}
.btn-primary:hover{transform:translateY(-2px);box-shadow:0 14px 40px -8px rgba(255,106,0,.6)}
.btn-ghost{background:transparent;color:var(--text);border-color:var(--border)}
.btn-ghost:hover{background:var(--card);border-color:#33405a}
.btn-lg{padding:16px 32px;font-size:1.05rem}

/* hero */
.hero{position:relative;min-height:88vh;display:flex;align-items:center;overflow:hidden;padding:80px 0}
.hero-bg{position:absolute;inset:0;z-index:0;pointer-events:none}
.orb{position:absolute;border-radius:50%;filter:blur(80px);opacity:.5;animation:float 14s ease-in-out infinite}
.orb-1{width:480px;height:480px;background:rgba(255,106,0,.32);top:-120px;right:-60px}
.orb-2{width:420px;height:420px;background:rgba(47,109,246,.28);bottom:-140px;left:-80px;animation-delay:-5s}
.orb-3{width:260px;height:260px;background:rgba(47,217,122,.18);top:40%;left:55%;animation-delay:-9s}
@keyframes float{0%,100%{transform:translateY(0) scale(1)}50%{transform:translateY(-30px) scale(1.06)}}
.grid-lines{position:absolute;inset:0;background-image:linear-gradient(rgba(255,255,255,.035) 1px,transparent 1px),linear-gradient(90deg,rgba(255,255,255,.035) 1px,transparent 1px);background-size:56px 56px;mask-image:radial-gradient(ellipse 70% 60% at 50% 40%,#000 30%,transparent 75%)}
.hero-inner{position:relative;z-index:1;max-width:var(--maxw);margin:0 auto;padding:0 24px}
.hero-tag{display:inline-block;padding:8px 16px;border-radius:999px;background:var(--accent-soft);color:var(--accent2);font-size:.85rem;font-weight:600;border:1px solid rgba(255,106,0,.25);margin-bottom:22px}
.hero-title{font-size:clamp(2.2rem,5.4vw,4rem);line-height:1.08;font-weight:900;letter-spacing:-.03em;max-width:18ch;margin-bottom:22px}
.grad{background:linear-gradient(100deg,#ff6a00,#ffb020 55%,#2f6df6);-webkit-background-clip:text;background-clip:text;color:transparent}
.hero-sub{font-size:clamp(1.02rem,1.8vw,1.25rem);color:var(--muted);max-width:62ch;margin-bottom:32px}
.hero-actions{display:flex;gap:14px;flex-wrap:wrap;margin-bottom:48px}
.hero-stats{display:grid;grid-template-columns:repeat(4,1fr);gap:16px}
.stat{background:linear-gradient(180deg,var(--card),transparent);border:1px solid var(--border);border-radius:var(--radius);padding:22px;text-align:center}
.stat strong{display:block;font-size:2rem;font-weight:800;background:linear-gradient(100deg,#fff,#ffb020);-webkit-background-clip:text;background-clip:text;color:transparent}
.stat span{color:var(--muted);font-size:.88rem}

/* sections */
.section{padding:88px 0}
.section-alt{background:var(--bg2);border-top:1px solid var(--border);border-bottom:1px solid var(--border)}
.section-title{font-size:clamp(1.7rem,3.4vw,2.5rem);font-weight:800;letter-spacing:-.02em;margin-bottom:14px}
.section-lede{color:var(--muted);font-size:1.06rem;max-width:64ch;margin-bottom:44px}

/* stages */
.program-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(210px,1fr));gap:16px}
.stage{background:var(--card);border:1px solid var(--border);border-radius:var(--radius);padding:24px;position:relative;overflow:hidden;transition:.3s var(--ease)}
.stage:hover{transform:translateY(-4px);border-color:#33405a}
.stage-num{font-size:.8rem;font-weight:700;color:var(--accent2);text-transform:uppercase;letter-spacing:.08em}
.stage h3{font-size:1.12rem;margin:8px 0 6px}
.stage .hours{color:var(--green);font-weight:700;font-size:.92rem}
.stage p{color:var(--muted);font-size:.9rem;margin-top:8px}

/* modules accordion */
.part{margin-bottom:28px}
.part-head{display:flex;align-items:center;gap:12px;margin-bottom:12px;padding-bottom:10px;border-bottom:1px solid var(--border)}
.part-head .pnum{font-size:.78rem;font-weight:800;color:var(--accent2);background:var(--accent-soft);border-radius:8px;padding:4px 10px;text-transform:uppercase;letter-spacing:.06em;white-space:nowrap}
.part-head h3{font-size:1.15rem;font-weight:700}
.module{background:var(--card);border:1px solid var(--border);border-radius:14px;margin-bottom:10px;overflow:hidden}
.module summary{list-style:none;cursor:pointer;display:flex;align-items:center;gap:14px;padding:18px 20px;transition:background .2s}
.module summary::-webkit-details-marker{display:none}
.module summary:hover{background:var(--card2)}
.module .midx{font-weight:800;color:var(--accent2);min-width:30px;text-align:right;font-variant-numeric:tabular-nums}
.module .mtitle{font-weight:600;flex:1}
.module .mhours{color:var(--muted);font-size:.85rem;white-space:nowrap;padding:4px 10px;border:1px solid var(--border);border-radius:999px}
.module .chev{color:var(--muted);transition:transform .3s var(--ease)}
.module[open] .chev{transform:rotate(180deg)}
.module .mbody{padding:4px 20px 20px 64px;color:var(--muted);font-size:.95rem}
.module[open] summary{border-bottom:1px solid var(--border)}

/* specializations */
.spec-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(250px,1fr));gap:16px}
.spec{background:var(--card);border:1px solid var(--border);border-radius:var(--radius);padding:26px;transition:.3s var(--ease)}
.spec:hover{transform:translateY(-4px);border-color:rgba(255,106,0,.4)}
.spec .sicon{font-size:1.8rem;margin-bottom:12px}
.spec h3{font-size:1.08rem;margin-bottom:8px}
.spec p{color:var(--muted);font-size:.92rem}

/* method */
.method-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:16px}
.method{background:var(--card);border:1px solid var(--border);border-radius:var(--radius);padding:22px}
.method .mkey{font-weight:700;color:var(--accent2);margin-bottom:6px;font-size:1rem}
.method p{color:var(--muted);font-size:.92rem}

/* roadmap */
.roadmap{display:flex;flex-direction:column;gap:0}
.road-item{display:flex;gap:18px;padding:22px 4px;border-bottom:1px solid var(--border);align-items:flex-start}
.road-item:last-child{border-bottom:0}
.road-num{flex:none;width:46px;height:46px;display:grid;place-items:center;border-radius:12px;background:var(--accent-soft);border:1px solid rgba(255,106,0,.28);color:var(--accent2);font-weight:800;font-size:1.15rem}
.road-body h3{font-size:1.12rem;margin-bottom:4px}
.road-body p{color:var(--muted);font-size:.95rem}

/* cta */
.cta{padding:96px 0}
.cta-inner{text-align:center;max-width:720px}
.cta-inner h2{font-size:clamp(1.8rem,4vw,2.6rem);font-weight:800;margin-bottom:14px}
.cta-inner p{color:var(--muted);margin-bottom:30px;font-size:1.06rem}


/* account & module checks */
.account{display:flex;align-items:center;margin-left:8px}
.btn-sm{padding:9px 16px;font-size:.9rem}
.user-chip{display:flex;align-items:center;gap:10px;padding:6px 14px 6px 6px;border:1px solid var(--border);border-radius:999px;background:var(--card);cursor:pointer;color:var(--text);font:inherit;transition:.2s var(--ease)}
.user-chip:hover{border-color:#33405a;background:var(--card2)}
.avatar{width:32px;height:32px;border-radius:50%;display:grid;place-items:center;background:linear-gradient(135deg,var(--accent),var(--accent2));color:#000;font-weight:800;font-size:.85rem}
.uname{font-weight:600;max-width:140px;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.uprog{font-size:.82rem;color:var(--accent2);font-weight:700;font-variant-numeric:tabular-nums}
.mcheck{flex:none;width:28px;height:28px;border-radius:8px;border:1px solid var(--border);background:transparent;color:transparent;cursor:pointer;font-size:.95rem;display:grid;place-items:center;transition:.2s var(--ease)}
.mcheck:hover{border-color:var(--green);color:rgba(47,217,122,.5)}
.mcheck.done{background:var(--green);border-color:var(--green);color:#06240f}
.mcheck:disabled{opacity:.5;cursor:wait}

/* modals */
.modal{position:fixed;inset:0;z-index:300;display:none;align-items:center;justify-content:center;padding:20px;background:rgba(4,6,10,.7);backdrop-filter:blur(6px)}
.modal.open{display:flex}
.modal-card{position:relative;width:100%;max-width:420px;max-height:90vh;overflow:auto;background:var(--bg2);border:1px solid var(--border);border-radius:18px;padding:28px;box-shadow:0 30px 80px -20px rgba(0,0,0,.7)}
.modal-close{position:absolute;top:14px;right:14px;width:32px;height:32px;border-radius:8px;border:0;background:var(--card);color:var(--muted);cursor:pointer;font-size:.95rem}
.modal-close:hover{color:var(--text)}
.modal-title{font-size:1.35rem;font-weight:800;margin-bottom:18px;letter-spacing:-.01em}
.auth-tabs{display:flex;gap:6px;background:var(--card);border:1px solid var(--border);border-radius:12px;padding:4px;margin-bottom:16px}
.auth-tab{flex:1;padding:9px;border:0;border-radius:9px;background:transparent;color:var(--muted);cursor:pointer;font:inherit;font-weight:600;transition:.2s}
.auth-tab.active{background:var(--accent);color:#0b0b0b}
.auth-error{color:var(--red);font-size:.88rem;min-height:20px;margin-bottom:10px}
.auth-form{display:flex;flex-direction:column;gap:12px}
.auth-form label{display:flex;flex-direction:column;gap:6px;font-size:.85rem;color:var(--muted)}
.auth-form input{background:var(--card);border:1px solid var(--border);border-radius:10px;padding:12px 14px;color:var(--text);font:inherit;font-size:.95rem}
.auth-form input:focus{outline:none;border-color:var(--accent)}
.auth-form .btn{margin-top:6px}

/* cabinet */
.cab-user{display:flex;align-items:center;gap:14px;margin-bottom:18px}
.cab-avatar{width:48px;height:48px;border-radius:50%;display:grid;place-items:center;background:linear-gradient(135deg,var(--accent),var(--accent2));color:#000;font-weight:800;font-size:1.1rem}
.cab-name{font-weight:700;font-size:1.05rem}
.cab-email{color:var(--muted);font-size:.85rem}
.cab-progress{margin-bottom:16px}
.cab-progress-head{display:flex;justify-content:space-between;font-size:.9rem;color:var(--muted);margin-bottom:8px}
.progress-track{height:10px;border-radius:999px;background:var(--card);border:1px solid var(--border);overflow:hidden}
.progress-fill{height:100%;background:linear-gradient(90deg,var(--accent),var(--accent2));border-radius:999px;transition:width .5s var(--ease)}
.cab-done{margin-bottom:16px;display:flex;flex-direction:column;gap:8px;max-height:220px;overflow:auto}
.cab-done-item{padding:10px 14px;background:var(--card);border:1px solid var(--border);border-radius:10px;font-size:.9rem}
.cab-empty{color:var(--muted);font-size:.9rem;padding:8px 0}
#cab-logout{width:100%;margin-top:6px}
.btn-danger{background:transparent;color:#ff6b6b;border:1px solid rgba(255,90,90,.42)}
.btn-danger:hover{background:rgba(255,70,70,.12);border-color:#ff5a5a;color:#ff7d7d}
.logout-btn{margin-left:8px;padding:9px 14px;font-size:.88rem;color:#ff6b6b;border:1px solid rgba(255,90,90,.35)}
.logout-btn:hover{background:rgba(255,70,70,.12);color:#ff7d7d}


/* standalone lesson page */
.back-link{color:var(--muted);font-weight:600;font-size:.95rem;margin-right:auto;transition:color .2s}
.back-link:hover{color:var(--text)}
.lesson-page{padding:40px 0 20px}
.lesson-wrap{max-width:860px}
#lesson-content .lesson-head{margin-top:6px}
@media (max-width:640px){ .lesson-page{padding:24px 0 10px} }

/* lesson modal */
.lesson-modal .lesson-card{max-width:820px;padding:0}
.lesson-card{position:relative;width:100%;max-height:92vh;overflow:hidden;display:flex;flex-direction:column;background:var(--bg2);border:1px solid var(--border);border-radius:18px;box-shadow:0 30px 80px -20px rgba(0,0,0,.7)}
.lesson-card .modal-close{position:absolute;top:14px;right:14px;z-index:5;background:rgba(0,0,0,.4)}
#lesson-content{overflow-y:auto;padding:32px 34px 12px;scroll-behavior:smooth}
.lesson-head{margin-bottom:20px}
.lesson-tag{display:inline-block;padding:4px 12px;border-radius:999px;background:var(--accent-soft);color:var(--accent2);font-size:.78rem;font-weight:700;margin-bottom:12px}
.lesson-head h2{font-size:clamp(1.4rem,3vw,2rem);font-weight:800;letter-spacing:-.02em;margin-bottom:6px}
.lesson-hours{color:var(--green);font-weight:700;font-size:.92rem}
.lesson-block{margin:26px 0;padding-bottom:8px}
.lesson-block h3{font-size:1.15rem;font-weight:700;margin-bottom:12px}
.lesson-text p{margin-bottom:12px;color:#d5dbe6}
.lesson-text ul{margin:12px 0 12px 20px;display:flex;flex-direction:column;gap:8px}
.lesson-text li{color:#c2cad8}
.lesson-text strong{color:var(--text)}
.formula{display:inline-block;font-family:ui-monospace,Menlo,Consolas,monospace;font-size:1.5rem;font-weight:700;padding:12px 22px;background:var(--card);border:1px solid var(--border);border-radius:12px;margin:10px 0;color:#fff}
.lesson-note{color:var(--muted);font-size:.92rem;margin-bottom:16px}

/* demos */
.demo{margin:14px 0;padding:18px;background:var(--card);border:1px solid var(--border);border-radius:14px}
.demo-svg{width:100%;max-width:440px;height:auto;display:block;margin:0 auto}
.demo-note{color:var(--muted);font-size:.86rem;margin-top:10px;text-align:center}
.ohm-grid{display:grid;grid-template-columns:1fr 1fr;gap:20px;margin-bottom:18px}
.ohm-slider{display:flex;flex-direction:column;gap:8px}
.ohm-slider label{font-size:.92rem;color:#c2cad8}
.ohm-slider input[type=range]{accent-color:var(--accent);width:100%}
.ohm-result{font-size:1.25rem;font-weight:700;margin-bottom:12px}
.ohm-result span{color:var(--accent2)}
.ohm-bar{height:10px;border-radius:999px;background:var(--bg);border:1px solid var(--border);overflow:hidden}
.ohm-fill{height:100%;background:linear-gradient(90deg,var(--blue),var(--accent));border-radius:999px;transition:width .2s var(--ease)}

/* homework */
.hw-item{background:var(--card);border:1px solid var(--border);border-radius:12px;padding:12px 16px;margin-bottom:10px}
.hw-item.done{border-color:rgba(47,217,122,.4)}
.hw-label{display:flex;align-items:flex-start;gap:12px;cursor:pointer}
.hw-label input{position:absolute;opacity:0;width:0;height:0}
.hw-box{flex:none;width:22px;height:22px;border-radius:6px;border:1px solid var(--border);display:grid;place-items:center;color:transparent;font-size:.85rem;transition:.15s;margin-top:1px}
.hw-label input:checked + .hw-box{background:var(--green);border-color:var(--green);color:#06240f}
.hw-text{color:#d5dbe6;font-size:.95rem}
.hw-item.done .hw-text{color:var(--muted);text-decoration:line-through}
.hw-hint{display:inline-block;margin:10px 0 0 34px;background:none;border:0;color:var(--accent2);cursor:pointer;font:inherit;font-size:.82rem;padding:0}
.hw-hint:hover{text-decoration:underline}
.hw-hint-text{margin:8px 0 0 34px;padding:8px 12px;background:var(--bg);border:1px solid var(--border);border-radius:8px;color:var(--muted);font-size:.88rem}

/* videos */
.video-grid{display:grid;grid-template-columns:1fr;gap:16px}
.video-card{background:var(--card);border:1px solid var(--border);border-radius:14px;overflow:hidden}
.video-frame{position:relative;aspect-ratio:16/9;background:#000}
.video-frame iframe{position:absolute;inset:0;width:100%;height:100%;border:0}
.video-meta{padding:12px 16px;display:flex;flex-direction:column;gap:4px}
.video-meta strong{font-size:.92rem;font-weight:600}
.video-meta span{color:var(--muted);font-size:.8rem}

/* 3D lab */
.lab3d{position:relative;width:100%;height:380px;border-radius:12px;overflow:hidden;background:var(--bg);border:1px solid var(--border);touch-action:pan-y}
.lab3d canvas{display:block}
.webgl-fallback{display:grid;place-items:center;height:100%;padding:24px;text-align:center;color:var(--muted);font-size:.95rem}
.sim-controls{display:flex;flex-wrap:wrap;gap:10px;margin-bottom:14px}
.sim-btn{padding:10px 16px;border-radius:10px;border:1px solid var(--border);background:var(--card);color:var(--text);cursor:pointer;font:inherit;font-size:.92rem;font-weight:600;transition:.15s}
.sim-btn:hover{border-color:#33405a;background:var(--card2)}
.sim-btn.active{background:var(--accent);border-color:var(--accent);color:#0b0b0b}
.sim-btn.switch-btn.active{background:rgba(255,90,90,.16);border-color:#ff5a5a;color:#ff7d7d}
.sim-status{font-size:.92rem;font-weight:600;margin-top:12px;min-height:22px}

/* tasks & quiz */
.task{background:var(--card);border:1px solid var(--border);border-radius:12px;padding:16px 18px;margin-bottom:12px}
.task-q{display:flex;gap:10px;margin-bottom:12px;color:#d5dbe6}
.task-num{flex:none;width:24px;height:24px;border-radius:7px;background:var(--accent-soft);color:var(--accent2);font-weight:700;display:grid;place-items:center;font-size:.85rem}
.task-io{display:flex;align-items:center;gap:10px;flex-wrap:wrap}
.task-input{width:140px;background:var(--bg);border:1px solid var(--border);border-radius:10px;padding:10px 12px;color:var(--text);font:inherit;font-size:.95rem}
.task-input:focus{outline:none;border-color:var(--accent)}
.task-unit{color:var(--muted);font-size:.9rem}
.task-feedback{margin-top:10px;min-height:20px}
.fb{font-weight:600}
.fb.good{color:var(--green)}
.fb.bad{color:#ff6b6b}
.quiz{margin-bottom:16px}
.quiz-q{margin-bottom:10px;font-weight:600}
.quiz-opts{display:flex;flex-direction:column;gap:8px}
.quiz-opt{text-align:left;background:var(--card);border:1px solid var(--border);border-radius:10px;padding:11px 14px;color:var(--text);cursor:pointer;font:inherit;font-size:.94rem;transition:.15s}
.quiz-opt:hover:not(:disabled){border-color:#33405a;background:var(--card2)}
.quiz-opt.correct{background:rgba(47,217,122,.16);border-color:var(--green);color:var(--green)}
.quiz-opt.wrong{background:rgba(255,80,80,.12);border-color:#ff5a5a;color:#ff7d7d}
.quiz-opt:disabled{cursor:default;opacity:.85}
.quiz-fb{margin-top:8px;min-height:20px}

.lesson-footer{padding:14px 34px 22px;border-top:1px solid var(--border)}
#lesson-complete{width:100%}
#lesson-complete:disabled{opacity:.45;cursor:not-allowed;box-shadow:none}

@media (max-width:640px){
  .lesson-card .modal-close{top:10px;right:10px}
  #lesson-content{padding:22px 18px 8px}
  .lesson-footer{padding:12px 18px 18px}
  .ohm-grid{grid-template-columns:1fr}
  .task-input{width:100%}
}

/* footer */
.site-footer{border-top:1px solid var(--border);padding:32px 0;background:var(--bg2)}
.footer-inner{display:flex;align-items:center;justify-content:space-between;gap:16px;flex-wrap:wrap}
.footer-note{color:var(--muted);font-size:.88rem}

/* reveal animation */
.reveal{opacity:0;transform:translateY(24px);transition:opacity .7s var(--ease),transform .7s var(--ease)}
.reveal.in{opacity:1;transform:none}

@media (max-width:820px){
  .nav-links,.nav-cta{display:none}
  .burger{display:flex}
  .nav-inner{justify-content:space-between}
  .nav-links.open{display:flex;position:absolute;top:100%;left:0;right:0;flex-direction:column;background:rgba(7,9,15,.98);border-bottom:1px solid var(--border);padding:16px 24px;gap:16px}
  .nav-links.open a{color:var(--text);font-size:1.05rem}
  .hero-stats{grid-template-columns:repeat(2,1fr)}
  .module .mbody{padding-left:20px}
  .section{padding:64px 0}
}
@media (prefers-reduced-motion:reduce){
  .orb,.reveal{animation:none;transition:none}
  .reveal{opacity:1;transform:none}
}