:root{
  --bg:#f3f5f9; --card:#fff; --ink:#1c2434; --mute:#667085; --line:#e2e6ee; --pri:#1d4ed8; --pri-d:#1e40af; --pri-l:#eaf0ff;
  --ok:#15803d; --ok-l:#e7f6ec; --bad:#b42318; --bad-l:#fdecea; --warn:#b45309; --warn-l:#fff4e0; --side:#111a2e;
}
*{box-sizing:border-box}
html,body{margin:0;height:100%}
body{font-family:"Leelawadee UI","Segoe UI",Tahoma,"Noto Sans Thai",sans-serif;font-size:15px;line-height:1.55;color:var(--ink);background:var(--bg)}
h1,h2,h3{margin:0 0 .5em;line-height:1.3} h1{font-size:1.45rem} h2{font-size:1.15rem} h3{font-size:1rem}
a{color:var(--pri);text-decoration:none} a:hover{text-decoration:underline}
img{max-width:100%}
.loading{padding:48px;text-align:center;color:var(--mute)}
.mute{color:var(--mute)} .small{font-size:.86rem} .right{text-align:right} .center{text-align:center} .nowrap{white-space:nowrap}
.pre{white-space:pre-wrap;word-break:break-word}

/* layout */
.shell{display:flex;min-height:100vh}
.side{width:226px;flex:none;background:var(--side);color:#cbd5e1;display:flex;flex-direction:column;position:sticky;top:0;height:100vh;overflow:auto}
.brand{padding:18px 18px 14px;font-weight:700;font-size:1.1rem;color:#fff;display:flex;gap:10px;align-items:center}
.brand img{width:28px;height:28px}
.brand small{display:block;font-weight:400;font-size:.74rem;color:#94a3b8}
.nav a{display:block;padding:9px 18px;color:#cbd5e1;border-left:3px solid transparent}
.nav a:hover{background:#1b2742;text-decoration:none;color:#fff}
.nav a.on{background:#1b2742;color:#fff;border-left-color:#60a5fa}
.nav .sep{margin:12px 18px 4px;font-size:.72rem;letter-spacing:.06em;text-transform:uppercase;color:#64748b}
.nav .cnt{float:right;background:#dc2626;color:#fff;border-radius:10px;font-size:.72rem;padding:0 7px}
.main{flex:1;min-width:0;display:flex;flex-direction:column}
.top{background:var(--card);border-bottom:1px solid var(--line);padding:10px 22px;display:flex;align-items:center;gap:12px;flex-wrap:wrap}
.top h1{flex:1;margin:0;font-size:1.15rem}
.top .who{font-size:.9rem;color:var(--mute)}
#view{padding:22px;max-width:1280px;width:100%}
#view.bare{padding:0;max-width:none}
.btn.menu-btn{display:none}

/* blocks */
.card{background:var(--card);border:1px solid var(--line);border-radius:10px;padding:18px;margin-bottom:16px}
.bar{display:flex;gap:8px;align-items:center;flex-wrap:wrap;margin-bottom:14px}
.bar .grow{flex:1}
.grid{display:grid;gap:14px;grid-template-columns:repeat(auto-fit,minmax(170px,1fr));margin-bottom:16px}
.stat{background:var(--card);border:1px solid var(--line);border-radius:10px;padding:14px 16px}
.stat b{display:block;font-size:1.7rem;line-height:1.2}
.stat span{color:var(--mute);font-size:.86rem}
.alert{padding:10px 14px;border-radius:8px;margin-bottom:14px;background:var(--pri-l);color:#1e3a8a}
.alert.err{background:var(--bad-l);color:var(--bad)} .alert.warn{background:var(--warn-l);color:var(--warn)} .alert.ok{background:var(--ok-l);color:var(--ok)}
.badge{display:inline-block;padding:1px 9px;border-radius:999px;font-size:.78rem;font-weight:600;background:#eef1f6;color:#475467;white-space:nowrap}
.badge.ok{background:var(--ok-l);color:var(--ok)} .badge.bad{background:var(--bad-l);color:var(--bad)}
.badge.warn{background:var(--warn-l);color:var(--warn)} .badge.pri{background:var(--pri-l);color:var(--pri)}

/* tables */
.tw{overflow-x:auto}
table{border-collapse:collapse;width:100%}
th,td{padding:8px 10px;text-align:left;border-bottom:1px solid var(--line);vertical-align:top}
th{font-size:.8rem;color:var(--mute);font-weight:600;white-space:nowrap;background:#fafbfd}
tr:hover td{background:#fafbfd}
td.act{white-space:nowrap;text-align:right}
.empty{padding:28px;text-align:center;color:var(--mute)}

/* forms */
label.f{display:block;margin-bottom:12px;font-size:.88rem;color:#344054;font-weight:600}
label.f>input,label.f>select,label.f>textarea{margin-top:4px;font-weight:400}
input[type=text],input[type=password],input[type=number],input[type=email],input[type=datetime-local],input[type=search],select,textarea{
  width:100%;padding:8px 10px;border:1px solid #cfd5e0;border-radius:7px;font:inherit;color:inherit;background:#fff}
input:focus,select:focus,textarea:focus{outline:2px solid #93b4ff;outline-offset:0;border-color:var(--pri)}
textarea{min-height:84px;resize:vertical}
.bar input,.bar select{width:auto}
.row{display:grid;gap:12px;grid-template-columns:repeat(auto-fit,minmax(180px,1fr))}
.ck{display:flex;gap:8px;align-items:flex-start;margin-bottom:8px;font-weight:400}
.ck input{margin-top:5px;flex:none}
.checklist{max-height:230px;overflow:auto;border:1px solid var(--line);border-radius:8px;padding:8px 10px}
.hint{font-size:.82rem;color:var(--mute);font-weight:400}
.btn{display:inline-flex;align-items:center;gap:6px;padding:7px 14px;border:1px solid #cfd5e0;border-radius:7px;background:#fff;color:var(--ink);font:inherit;cursor:pointer;white-space:nowrap}
.btn:hover{background:#f4f6fa;text-decoration:none}
.btn.primary{background:var(--pri);border-color:var(--pri);color:#fff} .btn.primary:hover{background:var(--pri-d)}
.btn.danger{color:var(--bad);border-color:#f1b5ae} .btn.danger:hover{background:var(--bad-l)}
.btn.ok{background:var(--ok);border-color:var(--ok);color:#fff}
.btn.sm{padding:3px 9px;font-size:.84rem}
.btn:disabled{opacity:.55;cursor:default}
.link{background:none;border:0;padding:0;color:var(--pri);cursor:pointer;font:inherit}

/* modal + toast */
.overlay{position:fixed;inset:0;background:rgba(15,23,42,.5);display:flex;align-items:flex-start;justify-content:center;padding:5vh 14px;overflow:auto;z-index:50}
.modal{background:#fff;border-radius:12px;width:100%;max-width:520px;box-shadow:0 20px 50px rgba(0,0,0,.25)}
.modal.wide{max-width:860px}
.mh{display:flex;align-items:center;padding:14px 18px;border-bottom:1px solid var(--line)} .mh h3{flex:1;margin:0;font-size:1.05rem}
.mh .x{border:0;background:none;font-size:1.5rem;line-height:1;cursor:pointer;color:var(--mute)}
.mb{padding:18px} .mf{padding:12px 18px;border-top:1px solid var(--line);display:flex;justify-content:flex-end;gap:8px}
#toasts{position:fixed;right:16px;bottom:16px;z-index:99;display:flex;flex-direction:column;gap:8px;max-width:min(420px,92vw)}
.toast{background:#1f2937;color:#fff;padding:10px 14px;border-radius:8px;box-shadow:0 6px 20px rgba(0,0,0,.25)}
.toast.err{background:var(--bad)} .toast.ok{background:var(--ok)}

/* login */
.login{min-height:100vh;display:flex;align-items:center;justify-content:center;padding:20px;background:linear-gradient(135deg,#111a2e,#1d4ed8)}
.login .card{width:100%;max-width:380px;padding:28px;margin:0}
.login h1{text-align:center;margin-bottom:2px} .login .sub{text-align:center;color:var(--mute);margin-bottom:20px}
.login .btn.primary{width:100%;justify-content:center;padding:10px}
.login .foot{display:flex;justify-content:flex-end;margin-top:14px}

/* question editor */
.optrow{display:flex;gap:8px;align-items:center;margin-bottom:8px}
.optrow input[type=text]{flex:1}
.thumb{max-height:90px;border:1px solid var(--line);border-radius:6px;display:block;margin:6px 0}
.thumb.s{max-height:38px;margin:0}

/* exam taking */
.exam{min-height:100vh;display:flex;flex-direction:column;user-select:none;-webkit-user-select:none}
.exam textarea,.exam input[type=text]{user-select:text;-webkit-user-select:text}
.ehead{position:sticky;top:0;z-index:5;background:var(--side);color:#fff;padding:10px 18px;display:flex;gap:14px;align-items:center;flex-wrap:wrap}
.ehead .t{flex:1;min-width:140px;font-weight:600}
.timer{font-variant-numeric:tabular-nums;font-size:1.35rem;font-weight:700;background:#1b2742;padding:2px 14px;border-radius:8px}
.timer.low{background:#b42318;animation:pulse 1s infinite}
@keyframes pulse{50%{opacity:.65}}
.savest{font-size:.82rem;color:#cbd5e1;min-width:92px}
.savest.off{color:#fca5a5;font-weight:600}
.ebody{flex:1;display:grid;grid-template-columns:minmax(0,1fr) 250px;gap:18px;padding:18px;max-width:1180px;width:100%;margin:0 auto;align-items:start}
.qpane{background:#fff;border:1px solid var(--line);border-radius:10px;padding:22px}
.qhead{display:flex;gap:12px;align-items:center;margin-bottom:12px;flex-wrap:wrap}
.qhead .no{font-weight:700;font-size:1.05rem} .qhead .sp{flex:1}
.qtext{font-size:1.06rem;white-space:pre-wrap;word-break:break-word;margin-bottom:14px}
.qimg{max-height:340px;border-radius:8px;border:1px solid var(--line);display:block;margin-bottom:14px}
.opt{display:flex;gap:10px;align-items:flex-start;padding:11px 13px;border:1px solid var(--line);border-radius:8px;margin-bottom:9px;cursor:pointer}
.opt:hover{background:#f7f9fc} .opt.sel{border-color:var(--pri);background:var(--pri-l)}
.opt input{margin-top:5px;flex:none;width:17px;height:17px}
.opt img{max-height:160px;display:block;margin-top:6px;border-radius:6px}
.qfoot{display:flex;justify-content:space-between;margin-top:18px;gap:8px}
.qnav{background:#fff;border:1px solid var(--line);border-radius:10px;padding:14px;position:sticky;top:70px}
.qgrid{display:grid;grid-template-columns:repeat(5,1fr);gap:6px;margin:10px 0}
.qgrid button{position:relative;border:1px solid #cfd5e0;background:#fff;border-radius:6px;padding:6px 0;cursor:pointer;font:inherit;font-size:.9rem}
.qgrid button.ans{background:#dbeafe;border-color:#93b4ff}
.qgrid button.cur{outline:2px solid var(--pri);outline-offset:1px;font-weight:700}
.qgrid button.flag::after{content:"";position:absolute;top:-3px;right:-3px;width:10px;height:10px;border-radius:50%;background:#f59e0b;border:2px solid #fff}
.legend{font-size:.8rem;color:var(--mute);display:flex;flex-direction:column;gap:3px}
.legend i{display:inline-block;width:12px;height:12px;border-radius:3px;border:1px solid #cfd5e0;margin-right:6px;vertical-align:-1px}
.legend i.a{background:#dbeafe;border-color:#93b4ff} .legend i.f{background:#f59e0b;border-color:#f59e0b;border-radius:50%}

/* my exams / results */
.xcard{display:flex;gap:16px;align-items:flex-start;flex-wrap:wrap}
.xcard .info{flex:1;min-width:230px}
.meta{display:flex;gap:6px 18px;flex-wrap:wrap;color:var(--mute);font-size:.9rem;margin:4px 0 8px}
.score{text-align:center;padding:10px}
.score b{font-size:3rem;line-height:1.1;display:block}
.qcard{border:1px solid var(--line);border-left:5px solid #cbd5e1;border-radius:8px;padding:14px 16px;margin-bottom:12px;background:#fff;break-inside:avoid}
.qcard.ok{border-left-color:var(--ok)} .qcard.bad{border-left-color:var(--bad)} .qcard.pend{border-left-color:#f59e0b} .qcard.part{border-left-color:#f59e0b}
.ropt{padding:5px 10px;border-radius:6px;margin-bottom:4px;border:1px solid transparent}
.ropt.correct{background:var(--ok-l);border-color:#b7e3c4} .ropt.wrong{background:var(--bad-l);border-color:#f5c2bc}
.ansbox{background:#f7f9fc;border:1px solid var(--line);border-radius:6px;padding:8px 12px;white-space:pre-wrap;word-break:break-word;margin:6px 0}
.grade{display:flex;gap:8px;align-items:center;flex-wrap:wrap;margin-top:10px;padding-top:10px;border-top:1px dashed var(--line)}
.grade input[type=number]{width:84px} .grade input[type=text]{flex:1;min-width:160px}
.hist{display:flex;align-items:flex-end;gap:6px;height:130px;padding-top:18px}
.hist div{flex:1;background:#93b4ff;border-radius:4px 4px 0 0;position:relative;min-height:2px}
.hist div.pass{background:#4ade80}
.hist div span{position:absolute;top:-18px;left:0;right:0;text-align:center;font-size:.76rem;color:var(--mute)}
.histx{display:flex;gap:6px;font-size:.72rem;color:var(--mute)} .histx span{flex:1;text-align:center}
.pbar{height:8px;background:#e8ecf3;border-radius:5px;overflow:hidden;min-width:80px}
.pbar i{display:block;height:100%;background:var(--pri)}

@media (max-width:860px){
  .side{position:fixed;z-index:40;left:-240px;transition:left .2s} .side.open{left:0;box-shadow:0 0 0 100vw rgba(0,0,0,.4)}
  .btn.menu-btn{display:inline-flex}
  #view{padding:14px}
  .ebody{grid-template-columns:1fr;padding:12px}
  .qnav{position:static}
  .qgrid{grid-template-columns:repeat(8,1fr)}
  .qpane{padding:16px}
}
@media print{
  .side,.top,.noprint,#toasts{display:none!important}
  body{background:#fff;font-size:12px} #view{padding:0;max-width:none}
  .card,.stat,.qcard{box-shadow:none;break-inside:avoid}
  a{color:inherit}
}