/* base.css — Biến màu, bố cục chung, màn hình bắt đầu, khung màn hình thi, câu hỏi, hộp thoại, kết quả
   (tách từ index.html; thứ tự nạp các file CSS phải giữ như trong index.html) */

:root{
  --ink:#1b1f24; --muted:#5b6570; --line:#cfd6dd; --soft:#f3f5f7; --band:#e6ecf2;
  --hdr:#20262c; --accent:#0b57d0; --accent-d:#0842a0; --brand:#d6001c;
  --red:#d0021b; --ok:#1e7e34; --bad:#c62828; --hl:#ffe45c;
}
*{box-sizing:border-box}
[hidden]{display:none !important}
html,body{height:100%;margin:0}
body{font-family:Arial,Helvetica,sans-serif;color:var(--ink);background:#fff;font-size:16px;overflow:hidden}
button{font-family:inherit}
:focus-visible{outline:3px solid #7aa7ff;outline-offset:1px}

/* ---------- Start screen ---------- */
#start{height:100%;overflow:auto;background:var(--soft);display:flex;align-items:flex-start;justify-content:center;padding:32px 16px}
.card{background:#fff;border:1px solid var(--line);border-radius:6px;max-width:680px;width:100%;padding:32px}
.logo{display:inline-block;background:var(--brand);color:#fff;font-weight:700;letter-spacing:.06em;padding:4px 12px;border-radius:2px;font-size:20px}
.card h1{font-size:24px;margin:20px 0 6px}
.card .sub{color:var(--muted);margin:0 0 20px}
.facts{display:flex;gap:24px;flex-wrap:wrap;padding:14px 0;border-top:1px solid var(--line);border-bottom:1px solid var(--line);margin-bottom:20px}
.facts div{font-size:14px;color:var(--muted)}
.facts b{display:block;font-size:20px;color:var(--ink)}
.card ul{padding-left:20px;line-height:1.7;margin:0 0 20px}
.card label{display:block;font-weight:700;margin-bottom:6px}
.card input[type=text]{width:100%;padding:10px 12px;border:1px solid #8a949e;border-radius:3px;font-size:16px;margin-bottom:20px}
.fine{font-size:13px;color:var(--muted);margin-top:16px}
.btn{border:1px solid var(--ink);background:#fff;color:var(--ink);padding:10px 22px;font-size:16px;border-radius:3px;cursor:pointer}
.btn.primary{background:var(--accent);border-color:var(--accent);color:#fff}
.btn.primary:hover{background:var(--accent-d)}
.btn.ghost:hover{background:var(--soft)}

/* ---------- Test screen ---------- */
#test{display:flex;flex-direction:column;height:100%}
.hdr{flex:none;background:var(--hdr);color:#fff;height:52px;padding:0 16px;display:grid;grid-template-columns:1fr auto 1fr;align-items:center}
.hdr .who{font-size:14px;color:#c9d1d9;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;display:flex;align-items:center;gap:14px}
.hdr .logo{font-size:16px;padding:3px 10px}
.timer{font-size:18px;font-weight:700;cursor:pointer;background:none;border:0;color:#fff;padding:6px 12px;border-radius:4px}
.timer:hover{background:rgba(255,255,255,.1)}
.timer.warn{color:#ff8f8f}
.hright{display:flex;justify-content:flex-end;gap:8px}
.hbtn{background:none;border:1px solid #56606a;color:#fff;padding:6px 14px;border-radius:3px;cursor:pointer;font-size:14px}
.hbtn:hover{background:rgba(255,255,255,.1)}
.zoomctl{display:flex;gap:4px}
.zbtn{padding:6px 11px;font-weight:700}
.zbtn:disabled{opacity:.4;cursor:default}
.zbtn:disabled:hover{background:none}
.band{flex:none;background:var(--band);border-bottom:1px solid var(--line);padding:10px 20px;font-size:16px}
.band b{margin-right:10px;font-size:17px}

.split{flex:1;display:flex;min-height:0;zoom:var(--examZoom,1)}
.pane{overflow:auto;min-width:0;min-height:0}
.pane-in{padding:22px 28px 60px}
@media (min-width:801px){
  #paneL{flex:0 0 var(--lw,50%)}
  #paneR{flex:1 1 0}
}
.divider{flex:none;width:10px;background:var(--soft);border-left:1px solid var(--line);border-right:1px solid var(--line);cursor:col-resize;position:relative;touch-action:none}
.divider::after{content:"";position:absolute;left:3px;top:50%;height:36px;width:2px;margin-top:-18px;background:#8a949e;box-shadow:2px 0 0 #8a949e}
.divider:hover,.divider.drag{background:#dfe6ec}
@media (max-width:800px){
  .split{flex-direction:column}
  .divider{display:none}
  .pane{flex:1 1 50%}
  #paneL{border-bottom:3px solid var(--line)}
  .hdr .who span.nm{display:none}
  .pane-in{padding:16px 16px 40px}
}

/* passage */
.passage h2{font-size:24px;margin:0 0 6px;line-height:1.3}
.passage .lead{font-style:italic;color:var(--muted);margin:0 0 20px;font-size:15px}
.para{display:grid;grid-template-columns:30px 1fr;margin:0 0 16px;font-size:17px;line-height:1.7}
.para .pl{font-weight:700}
.para p{margin:0}

/* questions */
.group{margin-bottom:30px}
.ghead{background:var(--soft);border:1px solid var(--line);border-radius:3px;padding:12px 16px;margin-bottom:10px}
.ghead h3{margin:0 0 6px;font-size:17px}
.ghead p{margin:4px 0;font-size:15px;line-height:1.5}
.ghead ul{margin:6px 0 0;padding-left:18px;font-size:14px;line-height:1.6}
.q{padding:14px 4px;border-bottom:1px solid #eceff2}
.qhead{display:flex;align-items:flex-start;gap:10px}
.qtext{flex:1;line-height:1.55}
.qnum{display:inline-flex;flex:none;min-width:28px;height:28px;padding:0 4px;align-items:center;justify-content:center;border:1px solid var(--ink);border-radius:2px;font-weight:700;font-size:14px;background:#fff}
.qnum.sm{min-width:24px;height:24px;font-size:13px}
.cur > .qhead .qnum, .gap.cur .qnum{background:var(--ink);color:#fff}
.opts{margin:10px 0 0 38px;display:flex;flex-direction:column;gap:8px}
.opts.row{flex-direction:row;flex-wrap:wrap;gap:8px 22px}
.opts label{display:flex;align-items:flex-start;gap:8px;cursor:pointer;line-height:1.45}
.opts input{margin-top:3px;width:16px;height:16px;flex:none}
.opts label b{display:inline-block;min-width:16px}
select{padding:7px 10px;font-size:15px;border:1px solid #8a949e;border-radius:3px;background:#fff;min-width:130px}
.selrow{margin:10px 0 0 38px}
.flag{flex:none;border:0;background:none;color:#a3acb5;cursor:pointer;font-size:18px;line-height:1;padding:2px 4px}
.flag:hover{color:#6c7680}
.flag.on{color:var(--red)}
.notes{border:1px solid var(--ink);border-radius:3px;padding:14px 18px;margin-top:6px}
.notes h4{margin:0 0 10px;font-size:16px}
.notes ul{margin:0;padding-left:20px}
.notes li{margin:0 0 14px;line-height:2.1}
.gap{display:inline-flex;align-items:center;gap:6px;vertical-align:middle;white-space:nowrap}
.gap input[type=text]{width:150px;padding:5px 8px;font-size:15px;border:1px solid #8a949e;border-radius:3px}

.listbox{border:1px solid var(--ink);border-radius:3px;padding:12px 16px;margin:0 0 10px;background:#fff}
.listbox h4{margin:0 0 8px;font-size:15px}
.listbox ul{list-style:none;margin:0;padding:0}
.listbox li{display:grid;grid-template-columns:34px 1fr;gap:4px;padding:3px 0;line-height:1.45;font-size:15px}

.qimg{max-width:50%;margin:0 auto 12px;text-align:center}
.qimg img{width:100%;height:auto;display:block;margin:0 auto;border:1px solid #c6ccd2;border-radius:4px;background:#fff}
.wfig .qimg{max-width:100%;margin:10px 0 14px}
.qimg .cap{margin:6px 0 0;font-size:12.5px;color:#5a6570;font-style:italic}
.qimgwrap{position:relative;display:block;line-height:0}
.imgfield{position:absolute;box-sizing:border-box}
.imgfield input[type=text]{width:100%;height:100%;box-sizing:border-box;text-align:center;padding:0 2px;font:700 12px Arial,sans-serif;color:#0a4a70;background:#eaf3fa;border:1px solid #7fa8c2;border-radius:2px}
.imgfield input[type=text]::placeholder{color:#7a95a8;font-weight:700}
.imgfield input[type=text]:focus{background:#fff;border-color:#0a9bd8;outline:0}
.imgfield.cur input{border-color:#0a9bd8;box-shadow:0 0 0 2px rgba(10,155,216,.25)}
.imgflags{display:flex;flex-wrap:wrap;justify-content:center;gap:8px;margin:8px 0 0}
.imgflags .imgflag{display:inline-flex;align-items:center;gap:2px;padding:2px 4px 2px 8px;border:1px solid #dde3e8;border-radius:14px;background:#f7f9fa;font-size:12px;color:#5a6570}
.imgflags .imgflag b{color:#0a4a70}
.listbox li b{font-weight:700}

/* highlight + menu */
.hl{background:var(--hl);color:#000;border-radius:2px}
.ctx{position:fixed;z-index:60;background:var(--hdr);border-radius:6px;padding:4px;box-shadow:0 4px 14px rgba(0,0,0,.3)}
.ctx button{background:none;border:0;color:#fff;font-size:14px;padding:8px 14px;cursor:pointer;border-radius:4px}
.ctx button:hover{background:rgba(255,255,255,.15)}

/* footer */
.foot{flex:none;border-top:1px solid var(--line);background:#fff;display:flex;align-items:center;justify-content:space-between;gap:16px;padding:8px 16px;min-height:64px}
.parts{display:flex;flex-wrap:wrap;gap:8px 18px;align-items:center;min-width:0}
.part{display:flex;align-items:center;gap:10px}
.part .pname{font-weight:700}
.part.off{background:none;border:1px solid var(--line);border-radius:3px;padding:8px 12px;cursor:pointer;font-size:14px;gap:12px}
.part.off:hover{background:var(--soft)}
.nums{display:flex;flex-wrap:wrap;gap:4px}
.nb{position:relative;width:34px;height:34px;background:#fff;border:1px solid transparent;border-radius:3px;font-size:15px;cursor:pointer;color:var(--ink)}
.nb:hover{background:var(--soft)}
.nb.ans{border-bottom:4px solid var(--ink);font-weight:700}
.nb.cur{border:2px solid var(--accent);background:#eaf1fe}
.nb.cur.ans{border-bottom:4px solid var(--accent)}
.nb.fl::after{content:"";position:absolute;top:0;right:0;border-style:solid;border-width:0 10px 10px 0;border-color:transparent var(--red) transparent transparent}
.fbtns{display:flex;gap:8px;flex:none}
.nav{width:46px;height:42px;background:var(--hdr);color:#fff;border:0;border-radius:3px;font-size:26px;line-height:1;cursor:pointer}
.nav:hover{background:#39424b}
.nav:disabled{background:#b8c0c8;cursor:default}
.submit{height:42px;padding:0 18px;background:var(--accent);color:#fff;border:0;border-radius:3px;font-size:15px;font-weight:700;cursor:pointer}
.submit:hover{background:var(--accent-d)}

/* modal */
.overlay{position:fixed;inset:0;background:rgba(15,20,25,.55);z-index:80;display:flex;align-items:center;justify-content:center;padding:16px}
.modal{background:#fff;border-radius:6px;max-width:520px;width:100%;padding:24px 26px;box-shadow:0 12px 40px rgba(0,0,0,.35)}
.modal h3{margin:0 0 12px;font-size:20px}
.modal .mbody{line-height:1.6;font-size:15px}
.modal .mbody ul{padding-left:20px;margin:8px 0}
.mbtns{display:flex;justify-content:flex-end;gap:10px;margin-top:20px}

/* ---------- Result ---------- */
#result{height:100%;overflow:auto;background:var(--soft)}
.rwrap{max-width:900px;margin:0 auto;padding:28px 16px 60px}
.rwrap h1{font-size:26px;margin:18px 0 4px}
.cards{display:grid;grid-template-columns:repeat(auto-fit,minmax(180px,1fr));gap:12px;margin:18px 0 24px}
.stat{background:#fff;border:1px solid var(--line);border-radius:6px;padding:16px}
.stat span{color:var(--muted);font-size:14px}
.stat b{display:block;font-size:30px;margin-top:4px}
table{width:100%;border-collapse:collapse;background:#fff;border:1px solid var(--line);font-size:15px}
th,td{text-align:left;padding:10px 12px;border-bottom:1px solid #eceff2;vertical-align:top}
th{background:#f7f9fa;font-size:14px}
td.ok{color:var(--ok);font-weight:700}
td.no{color:var(--bad);font-weight:700}
.exp{color:var(--muted);font-size:14px}
.note{font-size:13px;color:var(--muted);margin:12px 0 22px;line-height:1.5}
@media (max-width:640px){ .exp-col{display:none} }