/* ============================================================
   course.css — Trang chi tiết khóa học (port từ course-detail.html).
   Chỉ nạp trên single-vts_course. --cat-a/--cat-b set ở .single-course.
   ============================================================ */

/* ---------- Banner ---------- */
.banner{position:relative;background:radial-gradient(120% 140% at 85% 0%,#2A211A,#171310 60%);color:#EDE6DC;overflow:hidden;padding:34px 0 46px}
.banner .g1{position:absolute;top:-140px;right:-100px;width:480px;height:480px;border-radius:50%;background:radial-gradient(circle,rgba(15,80,26,.30),transparent 62%);filter:blur(8px)}
.banner .g2{position:absolute;bottom:-200px;left:-140px;width:440px;height:440px;border-radius:50%;background:radial-gradient(circle,rgba(212,175,55,.18),transparent 64%);filter:blur(8px)}
.banner .wrap{position:relative;z-index:1}
.crumb{font-size:13.5px;color:#A89E92;margin-bottom:18px;display:flex;flex-wrap:wrap;align-items:center;gap:7px}
.crumb a{color:#C9BFB2;transition:.15s}
.crumb a:hover{color:#fff}
.crumb .sep{opacity:.5}
.crumb .cur{color:#fff}
.b-cat{display:inline-block;background:rgba(15,80,26,.16);color:var(--cream);border:1px solid rgba(15,80,26,.32);font-size:12.5px;font-weight:700;padding:5px 13px;border-radius:30px;margin-bottom:16px;letter-spacing:.2px}
.banner h1{font-family:var(--font-display);font-weight:800;font-size:clamp(28px,4.6vw,46px);line-height:1.08;letter-spacing:-1.2px;color:#fff;margin-bottom:14px;max-width:760px}
.b-tagline{font-size:16.5px;color:#BDB3A6;max-width:660px;margin-bottom:22px}
.b-meta{display:flex;flex-wrap:wrap;align-items:center;gap:10px 26px}
.b-author{display:flex;align-items:center;gap:10px}
.b-author .av{width:42px;height:42px;border-radius:50%;display:grid;place-items:center;color:#fff;font-weight:700;font-size:15px;flex-shrink:0;box-shadow:0 0 0 2px rgba(255,255,255,.15)}
.b-author .nm{font-size:14.5px;font-weight:600;color:#fff;line-height:1.2}
.b-author .ro{font-size:12.5px;color:#A89E92}
.b-rate{display:flex;align-items:center;gap:8px}
.b-rate .sc{font-family:var(--font-display);font-weight:800;font-size:16px;color:var(--gold)}
.b-meta .mi{display:flex;align-items:center;gap:7px;font-size:14px;color:#C9BFB2}
.b-meta .mi svg{width:16px;height:16px;color:#8A8178}
.b-meta .mi b{color:#fff;font-weight:600}

.stars{position:relative;display:inline-block;font-size:15px;line-height:1;letter-spacing:1px;font-family:Arial,sans-serif}
.stars .base{color:rgba(255,255,255,.22)}
.stars .fill{position:absolute;top:0;left:0;white-space:nowrap;overflow:hidden;color:var(--gold)}
.stars.dark .base{color:#E4DACB}

/* ---------- Layout ---------- */
.stage{padding:34px 0 24px}
.cols{display:grid;grid-template-columns:1fr 372px;gap:34px;align-items:start}

.player{position:relative;border-radius:var(--radius);overflow:hidden;aspect-ratio:16/9;box-shadow:var(--shadow);cursor:pointer;color:#fff}
.player .bg{position:absolute;inset:0;background:linear-gradient(135deg,var(--cat-a),var(--cat-b))}
.player .bg::after{content:"";position:absolute;inset:0;background:radial-gradient(120% 90% at 80% 0%,rgba(255,255,255,.26),transparent 55%)}
.player .grain{position:absolute;inset:0;opacity:.13;mix-blend-mode:overlay;background-image:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='120' height='120'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='2'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E")}
.player .kw{position:absolute;left:32px;top:32px;right:32px;font-family:var(--font-display);font-weight:800;font-size:clamp(26px,3.6vw,40px);line-height:1.04;letter-spacing:-.8px;text-shadow:0 4px 18px rgba(0,0,0,.25)}
.player .cover-img{position:absolute;inset:0;width:100%;height:100%;object-fit:cover}
.player.has-img .kw{display:none}
.player.has-img::after{content:"";position:absolute;inset:0;background:linear-gradient(180deg,rgba(0,0,0,.18),transparent 38%,rgba(0,0,0,.34));pointer-events:none}
.player .play{position:absolute;left:50%;top:50%;transform:translate(-50%,-50%);width:84px;height:84px;border-radius:50%;background:rgba(255,255,255,.94);display:grid;place-items:center;box-shadow:0 18px 40px -14px rgba(0,0,0,.5);transition:.25s}
.player .play svg{width:32px;height:32px;color:var(--brand-deep);margin-left:4px}
.player:hover .play{transform:translate(-50%,-50%) scale(1.08)}
.player .play::before{content:"";position:absolute;inset:-10px;border-radius:50%;border:2px solid rgba(255,255,255,.5);animation:pulse 2.4s ease-out infinite}
@keyframes pulse{0%{transform:scale(.9);opacity:.7}70%{transform:scale(1.35);opacity:0}100%{opacity:0}}
.player .pv{position:absolute;left:20px;bottom:18px;background:rgba(0,0,0,.4);backdrop-filter:blur(4px);padding:7px 14px;border-radius:30px;font-size:13px;font-weight:600;display:flex;align-items:center;gap:7px}
.player .pv svg{width:14px;height:14px}
.vts-preview-open{overflow:hidden}
.vts-preview-modal{position:fixed;inset:0;z-index:100000;display:none;align-items:center;justify-content:center;padding:24px}
.vts-preview-modal.open{display:flex}
.vts-preview-backdrop{position:absolute;inset:0;border:0;background:rgba(15,12,10,.78);cursor:pointer}
.vts-preview-box{position:relative;z-index:1;width:min(980px,100%);aspect-ratio:16/9;background:#050505;border-radius:18px;box-shadow:0 30px 80px -24px rgba(0,0,0,.75);overflow:hidden}
.vts-preview-box iframe{display:block;width:100%;height:100%;border:0;background:#050505}
.vts-preview-close{position:absolute;right:12px;top:12px;z-index:2;border:0;border-radius:999px;padding:8px 12px;background:rgba(255,255,255,.92);color:var(--ink);font-weight:800;box-shadow:0 10px 22px -14px rgba(0,0,0,.7);cursor:pointer}
.vts-preview-close:hover{background:#fff}

.tabs{position:sticky;top:78px;z-index:30;display:flex;gap:4px;background:rgba(250,246,239,.9);backdrop-filter:blur(8px);border:1px solid var(--line);border-radius:14px;padding:5px;margin:26px 0 6px;overflow-x:auto;scrollbar-width:none}
.tabs::-webkit-scrollbar{display:none}
.tabs a{font-size:14.5px;font-weight:600;color:var(--ink-2);padding:9px 16px;border-radius:10px;white-space:nowrap;transition:.18s}
.tabs a:hover{color:var(--ink)}
.tabs a.active{background:var(--ink);color:#fff}

.sec{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:28px;margin-top:22px;box-shadow:var(--shadow-sm);scroll-margin-top:150px}
.sec h2{font-family:var(--font-display);font-weight:800;font-size:23px;letter-spacing:-.6px;margin-bottom:18px;display:flex;align-items:center;gap:10px}
.sec h2 .bar{width:5px;height:24px;border-radius:4px;background:linear-gradient(var(--brand),var(--brand-2))}
.sec p{color:var(--ink-2);font-size:15px}
.sec p+p{margin-top:12px}
.course-desc p{margin-bottom:12px}
.course-desc ul,.course-desc ol{margin:0 0 12px 20px;color:var(--ink-2)}

.learn{display:grid;grid-template-columns:1fr 1fr;gap:14px 26px}
.learn li{list-style:none;display:flex;gap:11px;font-size:14.5px;color:var(--ink-2);line-height:1.5}
.learn .ck{flex-shrink:0;width:24px;height:24px;border-radius:8px;background:var(--green-soft);color:var(--green);display:grid;place-items:center;margin-top:1px}
.learn .ck svg{width:14px;height:14px}

.reqs{list-style:none;display:flex;flex-direction:column;gap:10px}
.reqs li{display:flex;gap:11px;font-size:14.5px;color:var(--ink-2)}
.reqs .dot{flex-shrink:0;width:7px;height:7px;border-radius:50%;background:var(--brand);margin-top:9px}

.curr-top{display:flex;justify-content:space-between;align-items:center;flex-wrap:wrap;gap:10px;margin-bottom:16px;font-size:13.5px;color:var(--ink-3)}
.curr-top b{color:var(--ink)}
.curr-top .expand{font-weight:600;color:var(--brand-deep);cursor:pointer}
.chap{border:1px solid var(--line);border-radius:var(--radius-sm);overflow:hidden;margin-bottom:12px;transition:border-color .2s}
.chap.open{border-color:var(--line-2)}
.chap-h{display:flex;align-items:center;gap:14px;padding:16px 18px;cursor:pointer;background:var(--bg);transition:background .18s}
.chap-h:hover{background:var(--bg-2)}
.chap-h .ar{width:26px;height:26px;border-radius:8px;background:var(--surface);border:1px solid var(--line);display:grid;place-items:center;flex-shrink:0;transition:transform .3s}
.chap.open .chap-h .ar{transform:rotate(90deg);background:var(--ink);border-color:var(--ink);color:#fff}
.chap-h .ar svg{width:14px;height:14px}
.chap-h .ct{flex:1;font-family:var(--font-display);font-weight:700;font-size:16px;letter-spacing:-.3px}
.chap-h .cmeta{font-size:12.5px;color:var(--ink-3);white-space:nowrap}
.chap-b{max-height:0;overflow:hidden;transition:max-height .35s ease}
.lesson{display:flex;align-items:center;gap:13px;padding:13px 18px 13px 22px;border-top:1px solid var(--line);font-size:14px}
.lesson .ic{width:20px;height:20px;color:var(--ink-3);flex-shrink:0}
.lesson .ic svg{width:20px;height:20px}
.lesson .lt{flex:1;color:var(--ink-2)}
.lesson .free{font-size:11px;font-weight:700;color:var(--green);background:var(--green-soft);padding:3px 9px;border-radius:30px;letter-spacing:.2px}
.lesson .dur{font-size:12.5px;color:var(--ink-3);font-variant-numeric:tabular-nums;white-space:nowrap}
.lesson.lock .lt{color:var(--ink-3)}
.lesson[data-video]{cursor:pointer;transition:background .18s}
.lesson[data-video]:hover{background:var(--green-soft)}
.lesson[data-video]:hover .lt{color:var(--ink)}
.lesson[data-video]:focus-visible{outline:2px solid var(--green);outline-offset:-2px}

.inst{display:flex;gap:20px;align-items:flex-start}
.inst .av{width:96px;height:96px;border-radius:20px;display:grid;place-items:center;color:#fff;font-family:var(--font-display);font-weight:800;font-size:34px;flex-shrink:0;box-shadow:var(--shadow)}
.inst img.av{object-fit:cover}
.inst .nm{font-family:var(--font-display);font-weight:800;font-size:20px;letter-spacing:-.4px}
.inst .role{font-size:13.5px;color:var(--brand-deep);font-weight:600;margin-bottom:10px}
.inst .istats{display:flex;flex-wrap:wrap;gap:8px 20px;margin:10px 0 12px;font-size:13.5px;color:var(--ink-2)}
.inst .istats span{display:flex;align-items:center;gap:6px}
.inst .istats svg{width:15px;height:15px;color:var(--ink-3)}
.inst .bio{font-size:14.5px;color:var(--ink-2)}

.rev-sum{display:grid;grid-template-columns:auto 1fr;gap:30px;align-items:center;padding-bottom:22px;border-bottom:1px solid var(--line);margin-bottom:22px}
.rev-score{text-align:center}
.rev-score .big{font-family:var(--font-display);font-weight:800;font-size:58px;line-height:1;letter-spacing:-2px}
.rev-score .cnt{font-size:13px;color:var(--ink-3);margin-top:8px}
.rev-bars{display:flex;flex-direction:column;gap:8px}
.rbar{display:flex;align-items:center;gap:12px;font-size:13px;color:var(--ink-2)}
.rbar .lab{width:40px;display:flex;align-items:center;gap:3px;color:var(--ink-3)}
.rbar .lab svg{width:12px;height:12px;color:var(--gold)}
.rbar .track{flex:1;height:8px;border-radius:30px;background:var(--bg-2);overflow:hidden}
.rbar .fillb{height:100%;border-radius:30px;background:linear-gradient(90deg,var(--gold),#FFC65C);width:0;transition:width 1s cubic-bezier(.2,.7,.2,1)}
.rbar .pct{width:38px;text-align:right;font-weight:600;color:var(--ink)}
.review-msg{margin:0 0 14px;padding:11px 14px;border-radius:12px;font-size:14px;font-weight:600;border:1px solid var(--line)}
.review-msg.ok{background:#F0FAF5;color:#178A5A;border-color:#C7EEDB}
.review-msg.warn{background:#FFF7ED;color:var(--brand-deep);border-color:#FED7AA}
.review-box{margin:0 0 18px;padding:16px;border:1px solid var(--line);border-radius:14px;background:var(--bg)}
.course-review-form{display:flex;flex-direction:column;gap:12px}
.review-form-head{display:flex;align-items:flex-start;justify-content:space-between;gap:16px}
.review-form-head strong{display:block;font-family:var(--font-display);font-size:17px;color:var(--ink);letter-spacing:-.2px}
.review-form-head span{display:block;margin-top:3px;font-size:13px;color:var(--ink-3)}
.review-form-head label{min-width:132px}
.review-form-head select{width:100%;height:40px;border:1px solid var(--line-2);border-radius:10px;background:#fff;color:var(--ink);padding:0 10px;font-weight:700}
.course-review-form textarea{width:100%;border:1px solid var(--line-2);border-radius:12px;background:#fff;color:var(--ink);padding:12px 14px;resize:vertical;min-height:104px;font:inherit;line-height:1.5}
.course-review-form textarea:focus,.review-form-head select:focus{outline:none;border-color:var(--brand);box-shadow:0 0 0 3px rgba(15,80,26,.12)}
.review-actions{display:flex;justify-content:flex-end}
.rev-submit{border:0;border-radius:12px;padding:11px 18px;background:var(--brand);color:#fff;font-weight:800;box-shadow:0 12px 22px -16px var(--brand-deep);transition:.18s}
.rev-submit:hover{transform:translateY(-1px);background:var(--brand-deep)}
.review-locked{display:flex;align-items:center;gap:10px;color:var(--ink-2);font-size:14px}
.review-locked svg{width:18px;height:18px;color:var(--ink-3)}
.review-locked a{margin-left:auto;color:var(--brand-deep);font-weight:800}
.review{display:flex;gap:14px;padding:18px 0;border-bottom:1px solid var(--line)}
.review:last-child{border-bottom:none;padding-bottom:0}
.review.rev-hidden{display:none}
.review .av{width:44px;height:44px;border-radius:50%;display:grid;place-items:center;color:#fff;font-weight:700;font-size:15px;flex-shrink:0}
.review .top{display:flex;align-items:center;gap:10px;flex-wrap:wrap;margin-bottom:5px}
.review .who{font-weight:600;font-size:14.5px}
.review .when{font-size:12.5px;color:var(--ink-3)}
.review .txt{font-size:14.5px;color:var(--ink-2)}
.rev-more{margin-top:20px;width:100%;border:1.5px solid var(--line-2);border-radius:12px;padding:12px;font-weight:600;font-size:14.5px;color:var(--ink);transition:.18s}
.rev-more:hover{border-color:var(--ink);background:var(--bg)}

.rel-grid{display:grid;grid-template-columns:1fr 1fr;gap:16px}
.rel{display:flex;gap:14px;padding:12px;border:1px solid var(--line);border-radius:var(--radius-sm);transition:.22s}
.rel:hover{border-color:var(--line-2);box-shadow:var(--shadow);transform:translateY(-3px)}
.rel .thumb{width:104px;height:70px;border-radius:11px;flex-shrink:0;position:relative;overflow:hidden;color:#fff}
.rel .thumb .rb{position:absolute;inset:0}
.rel .thumb .rkw{position:absolute;inset:0;display:grid;place-items:center;padding:6px;text-align:center;font-family:var(--font-display);font-weight:800;font-size:12px;line-height:1.1;text-shadow:0 2px 8px rgba(0,0,0,.25)}
.rel .ri{display:flex;flex-direction:column;justify-content:center;gap:5px;min-width:0}
.rel .rt{font-family:var(--font-display);font-weight:700;font-size:14px;line-height:1.25;letter-spacing:-.2px;display:-webkit-box;-webkit-line-clamp:2;-webkit-box-orient:vertical;overflow:hidden}
.rel .rr{display:flex;align-items:center;gap:6px;font-size:12px;color:var(--ink-3)}
.rel .rp{font-family:var(--font-display);font-weight:800;font-size:14.5px}
.rel .rp .rwas{font-size:11.5px;color:var(--ink-3);text-decoration:line-through;font-weight:400;margin-left:6px;font-family:var(--font-body)}
.rel .rfree{color:var(--green);font-family:var(--font-display);font-weight:800;font-size:14px}

/* ---------- Sidebar ---------- */
.side{position:sticky;top:90px}
.buy{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);overflow:hidden;box-shadow:var(--shadow)}
.buy .cover{position:relative;aspect-ratio:16/10;color:#fff}
.buy .cover .bg{position:absolute;inset:0;background:linear-gradient(135deg,var(--cat-a),var(--cat-b))}
.buy .cover .bg::after{content:"";position:absolute;inset:0;background:radial-gradient(120% 90% at 80% 0%,rgba(255,255,255,.26),transparent 55%)}
.buy .cover .kw{position:absolute;left:18px;right:18px;top:50%;transform:translateY(-50%);font-family:var(--font-display);font-weight:800;font-size:24px;line-height:1.05;letter-spacing:-.5px;text-shadow:0 3px 14px rgba(0,0,0,.22)}
.buy .cover .cover-img{position:absolute;inset:0;width:100%;height:100%;object-fit:cover}
.buy .cover.has-img .kw{display:none}
.buy .cover .off{position:absolute;top:13px;left:13px;background:#fff;color:var(--brand-deep);font-weight:800;font-size:13px;padding:5px 11px;border-radius:9px;box-shadow:0 6px 14px -6px rgba(0,0,0,.4)}
.buy .pad{padding:22px}
.price-row{display:flex;align-items:baseline;gap:12px;flex-wrap:wrap}
.price-now{font-family:var(--font-display);font-weight:800;font-size:34px;letter-spacing:-1px;line-height:1}
.price-was{font-size:16px;color:var(--ink-3);text-decoration:line-through}
.price-save{margin-top:8px;display:inline-flex;align-items:center;gap:7px;font-size:13px;font-weight:600;color:var(--brand-deep);background:var(--brand-soft);padding:5px 11px;border-radius:30px}
.price-save svg{width:15px;height:15px;flex-shrink:0}
.countdown{display:flex;align-items:center;gap:8px;font-size:13px;color:var(--ink-2);margin-top:14px;background:var(--bg);border:1px dashed var(--line-2);border-radius:11px;padding:9px 12px}
.countdown svg{width:16px;height:16px;color:var(--brand)}
.countdown b{font-variant-numeric:tabular-nums;color:var(--ink);font-weight:700}
.single-course .btn{border:0;border-radius:12px;display:inline-flex;align-items:center;justify-content:center;gap:9px;font-weight:700;line-height:1.2;text-align:center;text-decoration:none;white-space:normal;cursor:pointer;transition:transform .18s,box-shadow .18s,background .18s,border-color .18s}
.single-course .btn:disabled{cursor:wait;opacity:.72;transform:none}
.single-course .btn-primary{color:#fff;background:linear-gradient(140deg,var(--brand),var(--brand-2));box-shadow:0 14px 28px -14px rgba(15,80,26,.85)}
.single-course .btn-primary:hover:not(:disabled){transform:translateY(-2px);box-shadow:0 18px 32px -14px rgba(15,80,26,.9)}
.single-course .btn-dark{color:#fff;background:var(--dark);box-shadow:0 12px 24px -16px rgba(0,0,0,.65)}
.single-course .btn-dark:hover:not(:disabled){transform:translateY(-2px);background:#241e18}
.single-course .btn svg{width:18px;height:18px;flex-shrink:0}
.buy .cta{display:flex;flex-direction:column;gap:10px;margin:18px 0 16px}
.buy .cta .btn{width:100%;min-height:52px;padding:14px 18px;font-size:15.5px}
.guarantee{display:flex;align-items:center;gap:9px;justify-content:center;font-size:12.5px;color:var(--ink-3);margin-bottom:18px}
.guarantee svg{width:16px;height:16px;color:var(--green)}
.inc-t{font-size:12.5px;font-weight:700;letter-spacing:.4px;text-transform:uppercase;color:var(--ink-3);margin-bottom:12px}
.inc{list-style:none;display:flex;flex-direction:column;gap:12px}
.inc li{display:flex;align-items:center;gap:12px;font-size:14px;color:var(--ink-2)}
.inc li b{color:var(--ink);font-weight:600}
.inc .ic{width:20px;height:20px;color:var(--ink-3);flex-shrink:0}
.inc .ic svg{width:20px;height:20px}
.share{margin-top:18px;padding-top:18px;border-top:1px solid var(--line);display:flex;align-items:center;gap:10px}
.share .lbl{font-size:13px;color:var(--ink-3);margin-right:auto}
.share a{width:34px;height:34px;border-radius:10px;display:grid;place-items:center;border:1px solid var(--line-2);color:var(--ink-2);transition:.18s}
.share a:hover{border-color:var(--ink);color:var(--ink);transform:translateY(-2px)}
.share svg{width:16px;height:16px}

.mbar{position:fixed;left:0;right:0;bottom:0;z-index:80;background:rgba(255,255,255,.96);backdrop-filter:blur(10px);border-top:1px solid var(--line);box-shadow:0 -10px 30px -20px rgba(0,0,0,.4);padding:11px 16px;display:none;align-items:center;gap:14px}
.mbar .mp .now{font-family:var(--font-display);font-weight:800;font-size:21px;letter-spacing:-.6px;line-height:1}
.mbar .mp .was{font-size:12px;color:var(--ink-3);text-decoration:line-through}
.mbar .btn{margin-left:auto;min-height:46px;padding:12px 22px;font-size:14.5px;white-space:nowrap}

/* ---------- Responsive ---------- */
@media(max-width:1100px){
  .cols{grid-template-columns:1fr;min-width:0}
  .cols>*{min-width:0}
  .side{position:static}
  .buy{display:none}
  .mbar{display:flex}
  .tabs{top:70px}
  .single-course{padding-bottom:74px}
}
@media(max-width:760px){
  .learn{grid-template-columns:1fr}
  .rel-grid{grid-template-columns:1fr}
  .rev-sum{grid-template-columns:1fr;gap:18px;text-align:center}
  .review-form-head{flex-direction:column}
  .review-form-head label{width:100%;min-width:0}
  .review-actions{justify-content:stretch}
  .rev-submit{width:100%}
}
@media(max-width:560px){
  .sec{padding:20px}
  .inst{flex-direction:column}
}