:root{
  --brand:#0050a2; --brand-dark:#003b78; --gold:#f7a81b;
  --ink:#1a1a1a; --muted:#5c6470; --line:#e4e7ec; --bg:#fff; --sidebar:#f4f6f9;
  --radius:14px; --maxw:760px;
}
*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{font-family:"Sarabun","Sukhumvit Set","Thonburi",-apple-system,"Segoe UI",Roboto,sans-serif;
  color:var(--ink);background:var(--bg);line-height:1.7;font-size:17px;-webkit-font-smoothing:antialiased}

/* ===== Top bar ===== */
.topbar{position:sticky;top:0;z-index:50;background:#fff;border-bottom:1px solid var(--line);
  display:flex;align-items:center;gap:14px;padding:12px 22px}
.logo-mark{width:34px;height:34px;border-radius:50%;background:var(--gold);display:flex;align-items:center;
  justify-content:center;color:var(--brand-dark);font-weight:800;font-size:13px;flex-shrink:0}
.logo-word{font-weight:800;color:var(--brand);font-size:20px;letter-spacing:.3px}
.logo-sub{color:var(--muted);font-weight:600;border-left:1px solid var(--line);padding-left:14px;margin-left:2px}
.topbar .spacer{flex:1}
.topbar a{text-decoration:none;color:var(--muted);font-weight:600;font-size:15px}
.topbar a:hover{color:var(--brand)}
.badge-replica{font-size:12px;color:var(--muted);background:#fff7e8;border:1px solid #f3d99a;
  padding:4px 10px;border-radius:999px;font-weight:600}

/* ===== MENU / landing ===== */
.menu-hero{background:linear-gradient(150deg,var(--brand),var(--brand-dark));color:#fff;padding:52px 28px}
.menu-hero .inner{max-width:1000px;margin:0 auto}
.menu-hero .eyebrow{font-size:13px;letter-spacing:2px;font-weight:700;opacity:.85;text-transform:uppercase}
.menu-hero h1{font-size:34px;font-weight:800;margin:10px 0 6px;line-height:1.2}
.menu-hero p{opacity:.9;font-size:17px}
.menu-wrap{max-width:1000px;margin:0 auto;padding:40px 28px 80px}
.menu-wrap h2{font-size:16px;color:var(--muted);letter-spacing:1px;font-weight:800;margin-bottom:18px}
.grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(280px,1fr));gap:20px}
.card{border:1px solid var(--line);border-radius:var(--radius);overflow:hidden;background:#fff;
  text-decoration:none;color:inherit;display:flex;flex-direction:column;transition:.18s;position:relative}
.card:hover{box-shadow:0 8px 26px rgba(0,0,0,.12);transform:translateY(-3px)}
.card.locked{opacity:.62;pointer-events:none}
.card .thumb{height:150px;background:linear-gradient(150deg,var(--brand),var(--brand-dark)) center/cover;position:relative}
.card .thumb .num{position:absolute;top:12px;left:12px;width:30px;height:30px;border-radius:50%;
  background:rgba(255,255,255,.92);color:var(--brand-dark);display:flex;align-items:center;justify-content:center;font-weight:800;font-size:15px}
.card .body{padding:16px 18px;flex:1;display:flex;flex-direction:column;gap:6px}
.card .body h3{font-size:18px;font-weight:800;line-height:1.35}
.card .body .en{font-size:13px;color:var(--muted)}
.card .body .meta{margin-top:auto;font-size:13px;color:var(--muted);display:flex;gap:10px;align-items:center;padding-top:8px}
.pill{font-size:11px;font-weight:700;padding:3px 9px;border-radius:999px}
.pill.ready{background:#eafaf0;color:#2e7d46}
.pill.soon{background:#f1f3f6;color:var(--muted)}

/* ===== COURSE layout ===== */
.shell{display:flex;min-height:calc(100vh - 59px)}
.sidebar{width:320px;flex-shrink:0;background:var(--sidebar);border-right:1px solid var(--line);
  padding:26px 18px;position:sticky;top:59px;height:calc(100vh - 59px);overflow-y:auto}
.back-link{display:inline-block;color:var(--muted);text-decoration:none;font-size:14px;font-weight:600;margin-bottom:14px}
.back-link:hover{color:var(--brand)}
.course-hero{border-radius:var(--radius);overflow:hidden;margin-bottom:20px;color:#fff;padding:20px 18px;position:relative;
  background:linear-gradient(180deg,rgba(0,0,0,.28),rgba(0,0,0,.42)),var(--hero,linear-gradient(150deg,var(--brand),var(--brand-dark))) center/cover}
.course-hero h1,.course-hero .progress-label{text-shadow:0 1px 6px rgba(0,0,0,.75)}
.course-hero h1{font-size:20px;line-height:1.3;font-weight:800}
.course-hero .h-en{font-weight:600;opacity:.9;font-size:14px}
.progress-wrap{margin-top:14px}
.progress-label{font-size:12px;letter-spacing:1px;opacity:.95;margin-bottom:6px;font-weight:700}
.progress-track{height:6px;background:rgba(255,255,255,.3);border-radius:999px;overflow:hidden}
.progress-fill{height:100%;width:0;background:var(--gold);transition:width .4s ease}
.nav-title{font-size:12px;font-weight:800;color:var(--muted);letter-spacing:1px;margin:8px 6px 10px}
.lesson-link{display:flex;align-items:center;gap:11px;width:100%;text-align:left;border:0;background:none;
  padding:11px 12px;border-radius:10px;cursor:pointer;color:var(--ink);font-size:15.5px;font-family:inherit;transition:background .15s;line-height:1.35}
.lesson-link:hover{background:#e9edf3}
.lesson-link.active{background:#fff;box-shadow:inset 3px 0 0 var(--brand);font-weight:700}
.lesson-dot{width:22px;height:22px;border-radius:50%;border:2px solid #c3ccd8;flex-shrink:0;display:flex;
  align-items:center;justify-content:center;font-size:12px;color:#9aa5b3;background:#fff}
.lesson-link.done .lesson-dot{background:var(--brand);border-color:var(--brand);color:#fff}
.main{flex:1}
.content{max-width:var(--maxw);margin:0 auto;padding:48px 28px 120px}
.lesson{display:none;animation:fade .35s ease}
.lesson.active{display:block}
@keyframes fade{from{opacity:0;transform:translateY(8px)}to{opacity:1;transform:none}}
.lesson h2{font-size:34px;font-weight:800;line-height:1.2;letter-spacing:-.5px}
.accent{width:56px;height:4px;background:var(--brand);border-radius:2px;margin:14px 0 30px}
.lesson p{margin:0 0 18px;color:#2b2f36}
.lesson h3{font-size:22px;font-weight:800;margin:34px 0 12px}

/* media */
.photo{width:100%;display:block;border-radius:var(--radius);margin:20px 0;box-shadow:0 3px 14px rgba(0,0,0,.10)}
.photo-hero{position:relative;border-radius:var(--radius);overflow:hidden;margin:20px 0;box-shadow:0 3px 14px rgba(0,0,0,.12)}
.photo-hero img{width:100%;display:block}
.photo-hero .overlay{position:absolute;inset:0;background:linear-gradient(180deg,rgba(0,0,0,.05),rgba(0,0,0,.55))}
.photo-hero .cap-lg{position:absolute;left:26px;bottom:22px;color:#fff;font-size:30px;font-weight:800;text-shadow:0 2px 12px rgba(0,0,0,.5);max-width:80%}
.fig{font-size:13px;color:var(--muted);margin:-8px 0 20px;text-align:center}
.gallery{display:grid;grid-template-columns:repeat(3,1fr);gap:12px;margin:20px 0}
.gallery img{width:100%;height:150px;object-fit:cover;border-radius:var(--radius);display:block}
.video-embed{position:relative;width:100%;aspect-ratio:16/9;margin:20px 0;border-radius:var(--radius);overflow:hidden;box-shadow:0 3px 14px rgba(0,0,0,.12);background:#0a2a4d}
.video-embed iframe{position:absolute;inset:0;width:100%;height:100%;border:0}

/* accordion */
.hint{display:inline-flex;align-items:center;gap:8px;background:#eef4fb;color:var(--brand-dark);font-weight:600;font-size:14.5px;padding:8px 14px;border-radius:999px;margin:6px 0 18px}
.acc{border:1px solid var(--line);border-radius:12px;overflow:hidden;margin-bottom:12px;background:#fff}
.acc summary{list-style:none;cursor:pointer;padding:16px 18px;display:flex;align-items:center;gap:14px;font-weight:700;font-size:17px;transition:background .15s}
.acc summary::-webkit-details-marker{display:none}
.acc summary:hover{background:#f7f9fc}
.acc .plus{width:28px;height:28px;flex-shrink:0;border-radius:50%;background:var(--brand);color:#fff;display:flex;align-items:center;justify-content:center;font-size:20px;font-weight:400;transition:transform .25s}
.acc[open] .plus{transform:rotate(45deg)}
.acc .body{padding:2px 18px 18px 60px;color:#2b2f36}
.acc .body ul{padding-left:20px;margin:8px 0}
.acc .body li{margin-bottom:8px}

/* quiz */
.quiz{border:1px solid var(--line);border-left:4px solid var(--gold);border-radius:12px;padding:20px 22px;margin:24px 0;background:#fffdf7}
.quiz .q{font-weight:800;margin-bottom:14px;font-size:18px}
.quiz .opt{display:block;width:100%;text-align:left;border:1px solid var(--line);background:#fff;padding:13px 16px;border-radius:10px;margin-bottom:10px;cursor:pointer;font-family:inherit;font-size:16px;transition:.15s}
.quiz .opt:hover{border-color:var(--brand);background:#f5f9ff}
.quiz .opt.correct{border-color:#2e9e5b;background:#eafaf0;font-weight:700}
.quiz .opt.wrong{border-color:#d64545;background:#fdeeee;opacity:.75}
.quiz .explain{display:none;margin-top:6px;padding:14px 16px;border-radius:10px;background:#eef4fb;color:var(--brand-dark);font-size:15.5px}
.quiz .explain.show{display:block}

ul.clean{margin:0 0 18px;padding-left:22px}
ul.clean li{margin-bottom:10px}
.callout{background:#f4f6f9;border-radius:12px;padding:18px 20px;margin:20px 0;color:#2b2f36}
.callout.center{text-align:center;font-weight:700;color:var(--brand-dark)}
.quote{background:#f4f6f9;border-left:4px solid var(--brand);border-radius:12px;padding:18px 20px;margin:20px 0;color:#2b2f36;font-style:italic}

.lesson-foot{margin-top:44px;padding-top:26px;border-top:1px solid var(--line);display:flex;justify-content:space-between;align-items:center;gap:12px}
.btn{border:0;border-radius:999px;padding:13px 30px;font-size:16px;font-weight:700;cursor:pointer;font-family:inherit;transition:.15s}
.btn-primary{background:var(--brand);color:#fff}
.btn-primary:hover{background:var(--brand-dark)}
.btn-ghost{background:none;color:var(--muted)}
.btn-ghost:hover{color:var(--ink)}
.btn-ghost[disabled]{opacity:.35;cursor:default}

footer{border-top:1px solid var(--line);padding:22px 28px;color:var(--muted);font-size:13.5px;text-align:center;background:var(--sidebar)}
footer a{color:var(--brand)}

.mnav{display:none}
@media(max-width:900px){
  .sidebar{display:none}
  .content{padding:30px 20px 100px}
  .lesson h2{font-size:27px}
  .mnav{display:flex;gap:8px;overflow-x:auto;padding:12px 16px;border-bottom:1px solid var(--line);background:var(--sidebar)}
  .mnav button{white-space:nowrap;border:1px solid var(--line);background:#fff;border-radius:999px;padding:8px 14px;font-family:inherit;font-size:14px;cursor:pointer}
  .mnav button.active{background:var(--brand);color:#fff;border-color:var(--brand)}
}