:root{
  --navy:#072a43; --navy2:#0d4f66; --teal:#19c3b1; --mint:#7ff0e0;
  --bg:#f4f7fa; --card:#fff; --text:#10202c; --dim:#5b7284; --line:#dbe5ec;
  --warn:#c2410c; --ok:#0f766e; --danger:#b42318;
  --radius:12px; --max:1040px;
}
@media (prefers-color-scheme: dark){
  :root{--bg:#06141f;--card:#0b2233;--text:#e3eef5;--dim:#93aebf;--line:#17425c;--ok:#5eead4;--warn:#fdba74;--danger:#fca5a5}
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;background:var(--bg);color:var(--text);font:16px/1.6 system-ui,-apple-system,"Segoe UI",Roboto,Arial,sans-serif}
.skip{position:absolute;left:-999px;top:0;background:#fff;color:#000;padding:.5rem 1rem;z-index:100}
.skip:focus{left:8px;top:8px}
a{color:var(--navy2)} @media (prefers-color-scheme:dark){a{color:var(--mint)}}
.top{position:sticky;top:0;z-index:20;display:flex;align-items:center;gap:1rem;padding:.55rem 1.25rem;background:var(--navy);border-bottom:2px solid var(--teal)}
.brand{display:flex}.brand img{display:block;height:38px;width:auto}
#nav{margin-left:auto;display:flex;align-items:center;gap:.25rem;flex-wrap:wrap}
#nav a,#nav button{color:#d7ecf5;background:none;border:0;font:inherit;text-decoration:none;padding:.45rem .8rem;border-radius:8px;cursor:pointer}
#nav a:hover,#nav button:hover,#nav a.on{background:rgba(255,255,255,.12);color:#fff}
#nav .cta{background:var(--teal);color:#032b33;font-weight:700}
.burger{display:none;margin-left:auto;background:none;border:1px solid rgba(255,255,255,.35);color:#fff;border-radius:8px;font-size:1.2rem;padding:.2rem .6rem}
@media (max-width:760px){.burger{display:block}#nav{display:none;position:absolute;left:0;right:0;top:100%;background:var(--navy);flex-direction:column;align-items:stretch;padding:.5rem 1rem 1rem}#nav.open{display:flex}}
main{max-width:var(--max);margin:0 auto;padding:1.5rem 1.25rem 3rem;min-height:70vh;outline:none}
.foot{text-align:center;color:var(--dim);font-size:.85rem;padding:1.5rem}
h1{font-size:1.9rem;line-height:1.2;margin:.2rem 0 .8rem} h2{margin:1.6rem 0 .6rem} h3{margin:1.2rem 0 .4rem}
.muted{color:var(--dim)} .center{text-align:center} .pad{padding:3rem 0}
.card{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:1.25rem 1.4rem;margin:1rem 0}
.narrow{max-width:440px;margin:2rem auto}
label{display:block;font-weight:600;margin:.9rem 0 .25rem}
input,select{width:100%;padding:.65rem .8rem;border:1px solid var(--line);border-radius:8px;font:inherit;background:var(--card);color:var(--text)}
input:focus,select:focus{outline:2px solid var(--teal);outline-offset:1px}
.btn{display:inline-block;border:0;border-radius:9px;padding:.65rem 1.2rem;font:inherit;font-weight:650;background:var(--navy2);color:#fff;cursor:pointer;text-decoration:none}
.btn:hover{filter:brightness(1.12)} .btn[disabled]{opacity:.55;cursor:wait}
.btn.accent{background:var(--teal);color:#032b33} .btn.ghost{background:transparent;color:var(--navy2);border:1px solid var(--line)}
@media (prefers-color-scheme:dark){.btn.ghost{color:var(--mint)}}
.btn.danger{background:var(--danger)} .btn.small{padding:.3rem .7rem;font-size:.88rem}
.row{display:flex;flex-wrap:wrap;gap:.6rem;align-items:center}.row.between{justify-content:space-between}
.msg{padding:.7rem .9rem;border-radius:8px;margin:.8rem 0;font-size:.95rem}
.msg.err{background:#fee4e2;color:#7a1710} .msg.ok{background:#d1fadf;color:#05603a}
@media (prefers-color-scheme:dark){.msg.err{background:#4a1d19;color:#fecdca}.msg.ok{background:#0b3d2a;color:#abefc6}}
.hero{background:linear-gradient(135deg,var(--navy),var(--navy2));color:#fff;border-radius:16px;padding:1.6rem 1.6rem 1.4rem;margin-bottom:1rem}
.hero h1{margin-top:0}.hero p{margin:.3rem 0;color:#cfe8f0}
.bar{height:10px;background:rgba(255,255,255,.2);border-radius:99px;overflow:hidden;margin:.7rem 0 .2rem}.bar>i{display:block;height:100%;background:var(--mint);width:0}
.mod h2{font-size:1.15rem;margin:0}.mod p{margin:.2rem 0 .6rem;color:var(--dim)}
.lessons{list-style:none;margin:0;padding:0}
.lessons li a{display:flex;align-items:center;gap:.7rem;padding:.55rem .4rem;border-top:1px solid var(--line);text-decoration:none;color:var(--text)}
.lessons li a:hover{background:rgba(25,195,177,.08)}
.dot{flex:0 0 1.6rem;height:1.6rem;border-radius:50%;display:grid;place-items:center;font-size:.8rem;border:1.5px solid var(--line);color:var(--dim)}
.dot.done{background:var(--teal);border-color:var(--teal);color:#032b33;font-weight:800}
.lessons .t{flex:1}.lessons .m{color:var(--dim);font-size:.85rem;white-space:nowrap}
.tag{font-size:.72rem;font-weight:700;letter-spacing:.04em;text-transform:uppercase;padding:.12rem .45rem;border-radius:6px;background:rgba(25,195,177,.18);color:var(--ok);margin-left:.4rem}
.hero .tag{background:rgba(255,255,255,.2);color:#e6fffb}
.soon{opacity:.75}
.crumbs{font-size:.9rem;color:var(--dim);margin-bottom:.4rem}
.lesson-body{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:1.2rem 1.6rem 1.6rem;overflow-wrap:anywhere}
.lesson-body h1{font-size:1.7rem}.lesson-body h2{border-bottom:2px solid var(--line);padding-bottom:.25rem;margin-top:2rem}
.lesson-body img,.lesson-body svg,.lesson-body video,.lesson-body iframe{max-width:100%;height:auto}
.lesson-body table{border-collapse:collapse;display:block;overflow-x:auto;max-width:100%;margin:1rem 0}
.lesson-body th,.lesson-body td{border:1px solid var(--line);padding:.45rem .7rem;text-align:left}
.lesson-body th{background:rgba(25,195,177,.12)}
.lesson-body pre{overflow:auto;background:#06141f;color:#d7e8f3;padding:.9rem;border-radius:8px}
.lesson-body code{font-size:.92em}
.lesson-body blockquote{border-left:4px solid var(--teal);margin:1rem 0;padding:.2rem 1rem;color:var(--dim)}
.video{position:relative;padding-top:56.25%;margin:0 0 1rem;border-radius:var(--radius);overflow:hidden;background:#000}.video iframe,.video video{position:absolute;inset:0;width:100%;height:100%;border:0}
.pager{display:flex;flex-wrap:wrap;gap:.6rem;justify-content:space-between;align-items:center;margin-top:1.2rem}
.paywall{text-align:center;padding:2rem 1rem}
table.t{width:100%;border-collapse:collapse;font-size:.92rem}table.t th,table.t td{text-align:left;padding:.45rem .5rem;border-bottom:1px solid var(--line);vertical-align:top}
.chips{display:flex;flex-wrap:wrap;gap:.6rem}.chip{background:var(--card);border:1px solid var(--line);border-radius:10px;padding:.5rem .9rem}.chip b{display:block;font-size:1.3rem}
.pill{display:inline-block;font-size:.78rem;padding:.1rem .5rem;border-radius:99px;background:var(--line);margin-right:.25rem}.pill.bad{background:#fee4e2;color:#7a1710}.pill.good{background:#d1fadf;color:#05603a}
.tabs{display:flex;gap:.3rem;flex-wrap:wrap;border-bottom:1px solid var(--line);margin:1rem 0}.tabs button{background:none;border:0;border-bottom:3px solid transparent;padding:.55rem .9rem;font:inherit;color:var(--dim);cursor:pointer}.tabs button.on{color:var(--text);border-color:var(--teal);font-weight:700}
.cert{border:2px solid var(--teal);text-align:center}.mono{font-family:ui-monospace,Menlo,Consolas,monospace}
@media (prefers-reduced-motion:reduce){html{scroll-behavior:auto}}
@media print{.top,.foot,.pager,.btn{display:none}.lesson-body{border:0;padding:0}}