:root{
  --pri:#0E7C66; --pri-d:#0A5C4C; --pri-l:#E3F4EE; --pri-xl:#F2FAF7;
  --acc:#E8A21C; --acc-l:#FDF3DC;
  --ink:#1D2B2F; --ink-s:#55656A; --line:#DCE6E2; --bg:#F4F8F6; --card:#fff;
  --ok:#168A52; --ok-bg:#E4F6EC; --bad:#C0392B; --bad-bg:#FCEBE9; --warn:#9A6A00; --warn-bg:#FFF4D6;
  --r:16px; --sh:0 4px 18px rgba(14,60,50,.08);
}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;font-family:'Sarabun',-apple-system,'Helvetica Neue',sans-serif;background:var(--bg);color:var(--ink);font-size:17px;line-height:1.75}
img{max-width:100%;display:block}
a{color:var(--pri-d)}
h1,h2,h3,h4{line-height:1.4;margin:0 0 10px}
h1{font-size:28px} h2{font-size:22px} h3{font-size:19px}
p{margin:0 0 12px}
.wrap{max-width:860px;margin:0 auto;padding:16px 14px 80px}
.muted{color:var(--ink-s)} .small{font-size:15px} .center{text-align:center}

/* แถบบน */
.topbar{position:sticky;top:0;z-index:20;background:rgba(255,255,255,.96);backdrop-filter:blur(8px);border-bottom:1px solid var(--line)}
.topbar-in{max-width:860px;margin:0 auto;padding:8px 14px;display:flex;align-items:center;justify-content:space-between;gap:10px}
.brand{display:flex;align-items:center;gap:10px;text-decoration:none;color:var(--ink);font-weight:800;line-height:1.2}
.brand-mark{display:inline-flex;align-items:center;justify-content:center;width:38px;height:38px;border-radius:11px;background:var(--pri);color:#fff;font-size:17px}
.brand-t small{display:block;font-weight:500;font-size:12.5px;color:var(--ink-s)}
.who{display:flex;align-items:center;gap:8px;font-size:14px;color:var(--ink-s);min-width:0}
.who b{color:var(--ink);max-width:130px;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;display:inline-block;vertical-align:bottom}
.linkbtn{background:none;border:none;color:var(--pri-d);font:inherit;font-size:14px;cursor:pointer;text-decoration:underline;padding:6px}
.readbar{height:3px;background:transparent} .readbar i{display:block;height:100%;width:0;background:var(--acc);transition:width .1s}

/* การ์ด/ปุ่ม */
.card{background:var(--card);border:1px solid var(--line);border-radius:var(--r);box-shadow:var(--sh);padding:20px 18px;margin-bottom:16px}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;border:none;border-radius:12px;padding:13px 22px;font:inherit;font-weight:700;cursor:pointer;text-decoration:none;min-height:50px;transition:.15s}
.btn-pri{background:var(--pri);color:#fff} .btn-pri:hover{background:var(--pri-d)}
.btn-acc{background:var(--acc);color:#2b1d00} .btn-acc:hover{filter:brightness(.95)}
.btn-ghost{background:#fff;color:var(--pri-d);border:2px solid var(--pri)} .btn-ghost:hover{background:var(--pri-xl)}
.btn-block{display:flex;width:100%}
.btn[disabled]{opacity:.5;cursor:not-allowed}
.row{display:flex;gap:10px;flex-wrap:wrap}
.pill{display:inline-block;border-radius:999px;padding:3px 12px;font-size:13.5px;font-weight:700;background:var(--pri-l);color:var(--pri-d)}
.pill.gray{background:#EDF1F0;color:var(--ink-s)} .pill.ok{background:var(--ok-bg);color:var(--ok)}
.pill.bad{background:var(--bad-bg);color:var(--bad)} .pill.acc{background:var(--acc-l);color:var(--warn)}

/* เข้าสู่ระบบ */
.login{max-width:520px;margin:24px auto}
.login h1{font-size:26px;color:var(--pri-d)}
label.f{display:block;font-weight:700;margin:14px 0 6px}
input[type=text],textarea,select{width:100%;font:inherit;padding:13px 14px;border:2px solid var(--line);border-radius:12px;background:#fff;color:var(--ink)}
input[type=text]:focus,textarea:focus{outline:none;border-color:var(--pri)}
.err{background:var(--bad-bg);color:var(--bad);border-radius:10px;padding:10px 14px;margin-top:12px;font-weight:600}

/* หน้าแรก */
.hero{position:relative;border-radius:22px;overflow:hidden;color:#fff;margin-bottom:16px;
  background:linear-gradient(135deg,#0A5C4C,#0E7C66 55%,#2E9E7E);min-height:230px;display:flex;align-items:flex-end}
.hero img.hero-bg{position:absolute;inset:0;width:100%;height:100%;object-fit:cover}
.hero::after{content:"";position:absolute;inset:0;background:linear-gradient(0deg,rgba(6,40,32,.82),rgba(6,40,32,.15) 70%)}
.hero-in{position:relative;z-index:1;padding:22px 20px;width:100%}
.hero .pill{background:rgba(255,255,255,.2);color:#fff}
.hero h1{color:#fff;margin:8px 0 6px;font-size:27px}
.hero p{margin:0;opacity:.95;font-size:16px}
.prog{display:flex;align-items:center;gap:16px}
.ring{--p:0;width:84px;height:84px;border-radius:50%;flex:none;display:grid;place-items:center;
  background:conic-gradient(var(--pri) calc(var(--p)*1%), #E3EBE8 0)}
.ring span{width:66px;height:66px;border-radius:50%;background:#fff;display:grid;place-items:center;font-weight:800;font-size:19px;color:var(--pri-d)}
.stat{display:flex;gap:10px;flex-wrap:wrap;margin-top:6px}
.stat div{background:var(--pri-xl);border:1px solid var(--line);border-radius:12px;padding:8px 14px;font-size:15px}
.stat b{display:block;font-size:19px;color:var(--pri-d)}

.chap{margin:22px 0 10px;display:flex;align-items:center;gap:12px}
.chap .no{background:var(--pri);color:#fff;border-radius:12px;padding:2px 12px;font-weight:800;white-space:nowrap}
.chap h2{margin:0;font-size:20px}
.chap-img{border-radius:16px;overflow:hidden;margin-bottom:10px;max-height:150px}
.chap-img img{width:100%;height:150px;object-fit:cover}
.tcard{display:flex;gap:12px;align-items:stretch;background:#fff;border:1px solid var(--line);border-radius:14px;margin-bottom:10px;overflow:hidden;text-decoration:none;color:inherit;transition:.15s}
.tcard:hover{border-color:var(--pri);box-shadow:var(--sh)}
.tcard .tn{flex:none;width:52px;background:var(--pri-l);color:var(--pri-d);font-weight:800;font-size:22px;display:grid;place-items:center}
.tcard.done .tn{background:var(--ok);color:#fff}
.tcard .tb{padding:11px 4px 11px 0;flex:1;min-width:0}
.tcard .tb b{display:block;line-height:1.45}
.tcard .tm{padding:8px 12px 8px 0;display:flex;flex-direction:column;gap:4px;justify-content:center;align-items:flex-end;font-size:13px}
.special{display:flex;gap:14px;align-items:center;border:2px dashed var(--pri);background:var(--pri-xl)}
.special.locked{opacity:.65;border-color:var(--line);background:#fafafa}
.special .ic{font-size:34px;line-height:1}

/* บทเรียน */
.crumb{font-size:14.5px;color:var(--ink-s);margin-bottom:6px}
.crumb a{color:var(--ink-s)}
.lesson h1{font-size:26px;color:var(--pri-d)}
.obj{background:var(--pri-xl);border-left:5px solid var(--pri);border-radius:10px;padding:12px 16px;margin:14px 0 18px}
.obj b{color:var(--pri-d)} .obj ul{margin:6px 0 0;padding-left:20px}
.lesson h2{margin:26px 0 10px;padding-bottom:6px;border-bottom:2px solid var(--pri-l);color:var(--pri-d);font-size:21px}
.lesson ul,.lesson ol{padding-left:22px;margin:0 0 14px} .lesson li{margin-bottom:6px}
.fig{margin:16px 0}
.fig img{border-radius:14px;width:100%;max-height:420px;object-fit:cover}
.fig figcaption{font-size:14.5px;color:var(--ink-s);text-align:center;margin-top:6px}
.callout{border-radius:12px;padding:13px 16px;margin:14px 0;border-left:5px solid}
.callout b.ct{display:block;margin-bottom:3px}
.callout.key{background:var(--pri-xl);border-color:var(--pri)} .callout.key b.ct{color:var(--pri-d)}
.callout.tip{background:var(--acc-l);border-color:var(--acc)} .callout.tip b.ct{color:var(--warn)}
.callout.warn{background:var(--warn-bg);border-color:#D49A00} .callout.warn b.ct{color:var(--warn)}
.callout.ex{background:#EEF3FB;border-color:#4A78C2} .callout.ex b.ct{color:#2D5497}
.callout p{margin:0}
.tablewrap{overflow-x:auto;margin:12px 0 16px;border:1px solid var(--line);border-radius:12px;background:#fff}
table.t{border-collapse:collapse;width:100%;min-width:480px;font-size:16px}
table.t th{background:var(--pri);color:#fff;text-align:left;padding:10px 12px;font-weight:700}
table.t td{padding:10px 12px;border-top:1px solid var(--line);vertical-align:top}
table.t tr:nth-child(even) td{background:#F9FCFB}
table.t td:first-child{font-weight:600;color:var(--pri-d)}
.cards{display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:12px;margin:12px 0 16px}
.cards .c{background:#fff;border:1px solid var(--line);border-radius:14px;padding:14px 16px;border-top:4px solid var(--pri)}
.cards .c b{display:block;color:var(--pri-d);margin-bottom:4px}
.steps{margin:12px 0 16px;counter-reset:s;display:grid;gap:10px}
.steps .s{background:#fff;border:1px solid var(--line);border-radius:12px;padding:12px 16px 12px 16px;border-left:5px solid var(--acc)}
.steps .s b{display:block;color:var(--ink)}
.kw{display:flex;flex-wrap:wrap;gap:8px;margin:6px 0 4px}
.act{background:var(--acc-l);border:1px dashed var(--acc);border-radius:14px;padding:14px 16px;margin:22px 0}
.act textarea{margin-top:8px;min-height:92px;background:#fff}
.nav2{display:flex;gap:10px;flex-wrap:wrap;margin-top:20px}
.nav2 .btn{flex:1 1 200px}

/* ข้อสอบ */
.qhead{display:flex;justify-content:space-between;align-items:center;gap:10px;margin-bottom:10px}
.bar{height:10px;border-radius:999px;background:#E3EBE8;overflow:hidden;margin-bottom:16px}
.bar i{display:block;height:100%;background:var(--pri);border-radius:999px;transition:width .25s}
.qtext{font-size:20px;font-weight:700;line-height:1.55;margin-bottom:16px}
.opt{display:flex;gap:12px;align-items:flex-start;width:100%;text-align:left;font:inherit;background:#fff;border:2px solid var(--line);border-radius:14px;padding:13px 14px;margin-bottom:10px;cursor:pointer;color:var(--ink);min-height:56px}
.opt:hover:not([disabled]){border-color:var(--pri);background:var(--pri-xl)}
.opt .k{flex:none;width:32px;height:32px;border-radius:50%;background:var(--pri-l);color:var(--pri-d);display:grid;place-items:center;font-weight:800;font-size:15px}
.opt.sel{border-color:var(--pri);background:var(--pri-l)}
.opt.right{border-color:var(--ok);background:var(--ok-bg)} .opt.right .k{background:var(--ok);color:#fff}
.opt.wrong{border-color:var(--bad);background:var(--bad-bg)} .opt.wrong .k{background:var(--bad);color:#fff}
.opt[disabled]{cursor:default}
.explain{border-radius:12px;padding:12px 16px;margin:6px 0 14px;font-size:16.5px}
.explain.ok{background:var(--ok-bg);border-left:5px solid var(--ok)}
.explain.bad{background:var(--bad-bg);border-left:5px solid var(--bad)}
.score-big{font-size:46px;font-weight:800;line-height:1.1}
.res{text-align:center}
.res .ring{width:130px;height:130px;margin:10px auto} .res .ring span{width:104px;height:104px;font-size:32px}
.rev{border:1px solid var(--line);border-radius:12px;padding:12px 14px;margin-bottom:10px;background:#fff}
.rev .qq{font-weight:700} .rev .your{color:var(--bad)} .rev .ans{color:var(--ok);font-weight:700}

.compare{display:grid;grid-template-columns:1fr 1fr;gap:12px;margin:12px 0}
.compare div{background:var(--pri-xl);border:1px solid var(--line);border-radius:12px;padding:12px;text-align:center}
.compare b{font-size:30px;display:block;color:var(--pri-d)}
table.plain{width:100%;border-collapse:collapse;font-size:16px}
table.plain td,table.plain th{padding:8px 6px;border-bottom:1px solid var(--line);text-align:left}

.toast{position:fixed;left:50%;bottom:22px;transform:translateX(-50%);background:#1D2B2F;color:#fff;padding:11px 18px;border-radius:12px;font-size:15px;z-index:50;max-width:90vw;box-shadow:0 8px 24px rgba(0,0,0,.25)}
.foot{font-size:14px;color:var(--ink-s);text-align:center;margin-top:30px}

@media (max-width:560px){
  body{font-size:16.5px} h1{font-size:24px}
  .who b{max-width:90px} .brand-t small{display:none}
  .compare{grid-template-columns:1fr 1fr}
  .tcard .tm{display:none}
}
@media print{
  .topbar,.btn,.nav2,.toast,.noprint{display:none!important}
  body{background:#fff} .card{box-shadow:none;border:1px solid #bbb}
}