/* Math House · cổng phụ huynh & quản trị. Cùng bảng màu với trang chủ. */
:root{
  --paper:#FBF7EE;--surface:#FFFFFF;--ink:#16243A;--muted:#5B6678;--line:#E4DCCB;
  --navy:#1E3A5F;--navy-ink:#FFFFFF;--amber:#F5B400;--amber-ink:#1A1300;
  --leaf:#3F8A2C;--leaf-bg:#E6F2DF;--warn:#B4551B;--warn-bg:#FBE9DC;--chip:#EFE7D4;
  --display:"Noto Serif",Georgia,"Times New Roman",serif;
  --body:"Be Vietnam Pro",system-ui,-apple-system,"Segoe UI",Roboto,sans-serif;
}
@media (prefers-color-scheme:dark){:root:not([data-theme="light"]){
  --paper:#111A27;--surface:#18243A;--ink:#EEF1F6;--muted:#A3AEC0;--line:#2A3A55;
  --navy:#0B1626;--navy-ink:#EEF1F6;--amber:#F7C232;--leaf:#7CC466;--leaf-bg:#1E3324;--warn:#F0A070;--warn-bg:#3A2418;--chip:#223250;color-scheme:dark}}
:root[data-theme="dark"]{
  --paper:#111A27;--surface:#18243A;--ink:#EEF1F6;--muted:#A3AEC0;--line:#2A3A55;
  --navy:#0B1626;--navy-ink:#EEF1F6;--amber:#F7C232;--leaf:#7CC466;--leaf-bg:#1E3324;--warn:#F0A070;--warn-bg:#3A2418;--chip:#223250;color-scheme:dark}

*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;background:var(--paper);color:var(--ink);font:16px/1.6 var(--body);min-height:100vh;display:flex;flex-direction:column}
.wrap{max-width:1080px;margin:0 auto;padding-left:max(16px,env(safe-area-inset-left));padding-right:max(16px,env(safe-area-inset-right));width:100%}
h1,h2,h3{font-family:var(--display);font-weight:700;line-height:1.15;margin:0;letter-spacing:.01em}
p{margin:0}
a{color:inherit}
:focus-visible{outline:3px solid var(--amber);outline-offset:2px;border-radius:4px}

/* Thanh trên */
.top{background:var(--navy);color:var(--navy-ink);position:sticky;top:0;z-index:5}
.bar{display:flex;align-items:center;gap:20px;padding-block:10px;flex-wrap:wrap}
.brand{display:flex;align-items:center;gap:10px;text-decoration:none}
.brand svg{width:34px;height:34px}
.brand b{font:700 19px/1 var(--display);letter-spacing:.06em}
.top nav{display:flex;gap:4px 16px;margin-left:auto;flex-wrap:wrap}
.top nav a{text-decoration:none;font-size:15px;opacity:.85;padding:4px 0}
.top nav a:hover{opacity:1;text-decoration:underline;text-underline-offset:4px}
@media (max-width:560px){.top nav{margin-left:0;width:100%;gap:4px 14px}.top nav a{font-size:14px}}

.page{flex:1;padding-block:28px 56px;display:grid;gap:24px;align-content:start}
.foot{background:var(--navy);color:var(--navy-ink);font-size:13px;opacity:.95}
.foot .wrap{display:flex;justify-content:space-between;gap:12px;flex-wrap:wrap;padding-block:16px}

/* Thẻ, nút, ô nhập */
.card{background:var(--surface);border:1px solid var(--line);border-radius:14px;padding:22px}
.card h2{font-size:24px}
.narrow{max-width:420px;margin:24px auto 0;width:100%}
.muted{color:var(--muted)}
.small{font-size:14px}
.stack{display:grid;gap:14px}
.row{display:flex;gap:10px;align-items:center;flex-wrap:wrap}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;font:600 15px/1 var(--body);padding:12px 18px;border-radius:9px;border:2px solid transparent;cursor:pointer;text-decoration:none;min-height:44px}
.btn-amber{background:var(--amber);color:var(--amber-ink)}
.btn-navy{background:var(--navy);color:var(--navy-ink)}
.btn-ghost{background:transparent;border-color:var(--line);color:var(--ink)}
.btn-sm{padding:8px 12px;font-size:14px;min-height:36px}
.btn-danger{background:transparent;border-color:var(--warn);color:var(--warn)}
.btn[disabled]{opacity:.5;cursor:default}
label{display:grid;gap:6px;font-size:14px;font-weight:600}
input,select,textarea{font:16px var(--body);color:var(--ink);background:var(--paper);border:1px solid var(--line);border-radius:9px;padding:11px 12px;width:100%}
textarea{min-height:90px;resize:vertical}
input[type=checkbox]{width:20px;height:20px;accent-color:var(--navy)}
.check{display:flex;gap:10px;align-items:center;font-weight:500}
.msg{padding:10px 14px;border-radius:9px;font-size:15px}
.msg.ok{background:var(--leaf-bg);color:var(--leaf)}
.msg.err{background:var(--warn-bg);color:var(--warn)}
.msg.info{background:var(--chip);color:var(--ink)}
.pill{display:inline-block;font-size:12px;font-weight:600;padding:3px 9px;border-radius:999px;background:var(--chip);color:var(--muted);white-space:nowrap}
.pill.ok{background:var(--leaf-bg);color:var(--leaf)}
.pill.warn{background:var(--warn-bg);color:var(--warn)}

/* Trang phụ huynh */
.hello{display:flex;justify-content:space-between;align-items:end;gap:12px;flex-wrap:wrap}
.hello h1{font-size:clamp(28px,5vw,38px)}
.kids{display:flex;gap:8px;flex-wrap:wrap}
.kids a{padding:9px 14px;border-radius:999px;border:1px solid var(--line);background:var(--surface);text-decoration:none;font-weight:600;font-size:15px}
.kids a[aria-current="page"]{background:var(--navy);color:var(--navy-ink);border-color:var(--navy)}
.ai{border-left:4px solid var(--amber);background:var(--surface);border-radius:0 14px 14px 0;padding:18px 20px;display:grid;gap:8px}
.ai .lbl{font:600 12px/1 var(--body);letter-spacing:.08em;text-transform:uppercase;color:var(--muted)}
.ai p.text{font-size:16.5px}
.ai .loading{color:var(--muted);display:flex;gap:10px;align-items:center}
.spin{width:16px;height:16px;border:2px solid var(--line);border-top-color:var(--navy);border-radius:50%;animation:sp 1s linear infinite}
@keyframes sp{to{transform:rotate(360deg)}}
@media (prefers-reduced-motion:reduce){.spin{animation:none}}
.stats{display:grid;grid-template-columns:repeat(3,1fr);gap:10px}
.stat{background:var(--surface);border:1px solid var(--line);border-radius:12px;padding:14px 16px}
.stat b{display:block;font:700 28px/1.1 var(--display);font-variant-numeric:tabular-nums;color:var(--navy)}
.stat span{font-size:13px;color:var(--muted)}
:root[data-theme="dark"] .stat b{color:var(--amber)}
@media (prefers-color-scheme:dark){:root:not([data-theme="light"]) .stat b{color:var(--amber)}}
.month-bar{display:flex;justify-content:space-between;align-items:center;gap:12px;flex-wrap:wrap}
.month-bar select{width:auto;min-width:180px}
.sessions{display:grid;gap:10px}
.session{background:var(--surface);border:1px solid var(--line);border-radius:12px;padding:14px 16px;display:grid;gap:6px}
.session.absent{background:var(--warn-bg);border-color:transparent}
.session .when{display:flex;gap:8px;align-items:center;flex-wrap:wrap;font-size:14px;color:var(--muted)}
.session .when b{color:var(--ink);font-variant-numeric:tabular-nums}
.session .topic{font-weight:600}
.session dl{margin:0;display:grid;grid-template-columns:auto 1fr;gap:4px 12px;font-size:15px}
.session dt{color:var(--muted)}
.session dd{margin:0}
.scores-wrap{overflow-x:auto;border:1px solid var(--line);border-radius:12px;background:var(--surface)}
table{border-collapse:collapse;width:100%;font-size:15px}
th,td{padding:10px 12px;border-bottom:1px solid var(--line);text-align:left;white-space:nowrap}
th{font-size:12px;letter-spacing:.06em;text-transform:uppercase;color:var(--muted);font-weight:600}
td.num,th.num{text-align:center;font-variant-numeric:tabular-nums}
tr:last-child td{border-bottom:0}
.chart{width:100%;height:auto;display:block}
.empty{padding:22px;text-align:center;color:var(--muted);background:var(--surface);border:1px dashed var(--line);border-radius:12px}
@media (max-width:560px){.stats{grid-template-columns:repeat(3,1fr);gap:6px}.stat{padding:10px}.stat b{font-size:22px}}

/* Bảng tin */
.posts{display:grid;gap:18px}
.post{background:var(--surface);border:1px solid var(--line);border-radius:14px;overflow:hidden}
.post header{padding:16px 18px 10px;display:grid;gap:4px}
.post h3{font-size:21px}
.post .body{padding:0 18px 12px;color:var(--muted)}
.grid-photos{display:grid;grid-template-columns:repeat(auto-fill,minmax(150px,1fr));gap:4px;padding:0 4px 4px}
.grid-photos a{display:block;aspect-ratio:1;overflow:hidden;background:var(--chip)}
.grid-photos img{width:100%;height:100%;object-fit:cover;display:block}

/* Quản trị */
.toolbar{display:flex;gap:10px;align-items:center;flex-wrap:wrap;justify-content:space-between}
.search{max-width:320px}
.acc-list{display:grid;gap:8px}
.acc{display:grid;grid-template-columns:1fr auto;gap:8px 14px;align-items:center;background:var(--surface);border:1px solid var(--line);border-radius:12px;padding:12px 14px}
.acc .who b{font-variant-numeric:tabular-nums}
.acc .who small{display:block;color:var(--muted);font-size:13px}
.acc .act{display:flex;gap:6px;flex-wrap:wrap;justify-content:end}
@media (max-width:560px){.acc{grid-template-columns:1fr}.acc .act{justify-content:start}}
.issued{border:2px solid var(--amber);background:var(--surface);border-radius:14px;padding:18px;display:grid;gap:10px}
.issued .pw{font:700 34px/1 var(--display);letter-spacing:.18em;font-variant-numeric:tabular-nums}
.issued textarea{min-height:110px;font-size:15px}
.tabs{display:flex;gap:6px;flex-wrap:wrap}
.tabs a{padding:8px 12px;border-radius:9px;text-decoration:none;font-weight:600;font-size:14px;border:1px solid var(--line);background:var(--surface)}
.tabs a[aria-current="page"]{background:var(--navy);color:var(--navy-ink);border-color:var(--navy)}
.badge{display:inline-grid;place-items:center;min-width:20px;height:20px;padding:0 6px;border-radius:999px;background:var(--warn);color:#fff;font-size:12px;font-weight:700;margin-left:4px}
.previews{display:grid;grid-template-columns:repeat(auto-fill,minmax(90px,1fr));gap:6px}
.previews img{width:100%;aspect-ratio:1;object-fit:cover;border-radius:8px;display:block}
.problems{max-height:420px;overflow:auto;border:1px solid var(--line);border-radius:12px;background:var(--surface)}
.print-list{display:none}
@media print{
  .top,.foot,.no-print{display:none!important}
  body{background:#fff;color:#000}
  .print-list{display:block}
}

/* ---------- Ngân hàng câu hỏi ---------- */
.qbrowse{display:grid;grid-template-columns:minmax(240px,320px) 1fr;gap:18px;align-items:start}
@media (max-width:820px){.qbrowse{grid-template-columns:1fr}}
.qtree{padding:14px;font-size:14px;max-height:80vh;overflow:auto;position:sticky;top:12px}
@media (max-width:820px){.qtree{position:static;max-height:none}}
.qtree details{margin:4px 0}.qtree details details{margin-left:10px}
.qtree summary{cursor:pointer;padding:3px 0}
.qtree ul{list-style:none;margin:2px 0 6px 14px;padding:0}.qtree li{padding:3px 0}
.qtree a{color:var(--ink);text-decoration:none}.qtree a:hover{text-decoration:underline}
.qtree a[aria-current]{font-weight:700;color:var(--navy);text-decoration:underline}
.qtree-sub{margin:8px 0 2px;font-size:12px;text-transform:uppercase;letter-spacing:.04em;color:var(--muted)}
.q{padding:16px 18px}
.qhead{display:flex;flex-wrap:wrap;gap:8px;align-items:center;margin-bottom:8px}
.qhead code{font-size:12px;background:var(--chip);padding:2px 6px;border-radius:6px}
.qstem{line-height:1.65;overflow-x:auto}
.qfig{display:block;max-width:100%;height:auto;margin:10px auto;max-height:340px;background:#fff;border-radius:6px;padding:4px}
.qfig-miss{display:inline-block;margin:6px 0;padding:6px 10px;border:1px dashed var(--warn);color:var(--warn);border-radius:8px;font-size:13px}
.qcenter{text-align:center}
.qtable{overflow-x:auto;margin:8px 0}.qtable table{border-collapse:collapse;margin:0 auto}.qtable td{border:1px solid var(--line);padding:4px 10px;text-align:center}
.qchoices{list-style:none;padding:0;margin:10px 0;display:grid;gap:6px}
.qchoices.tn{grid-template-columns:repeat(auto-fit,minmax(200px,1fr))}
.qchoices li{padding:8px 10px;border:1px solid var(--line);border-radius:10px;background:var(--surface)}
.qchoices li.right{border-color:var(--leaf);background:var(--leaf-bg)}
.qans{margin:10px 0}
.qsol{margin-top:10px;border-top:1px dashed var(--line);padding-top:8px}
.qsol summary{cursor:pointer;font-weight:600;color:var(--navy)}
.qsol>div{margin-top:8px;line-height:1.65;overflow-x:auto}
.qsol ul.plain,.qstem ul.plain{list-style:none;padding-left:4px}

/* ---------- Luyện tập ---------- */
.practice-ch{padding:14px 16px}.practice-ch>summary{cursor:pointer}
.qopts{display:grid;gap:8px;margin:12px 0}
.qopt{display:flex;gap:10px;align-items:flex-start;padding:10px 12px;border:1px solid var(--line);border-radius:10px;background:var(--surface);cursor:pointer;font-weight:400}
.qopt:has(input:checked){border-color:var(--navy);box-shadow:0 0 0 2px color-mix(in srgb,var(--navy) 25%,transparent)}
.qopt input{margin-top:4px;flex:none;width:18px;height:18px}
.qds{display:grid;gap:8px;margin:12px 0}
.qds-row{display:grid;grid-template-columns:1fr auto;gap:10px;align-items:center;padding:8px 12px;border:1px solid var(--line);border-radius:10px;background:var(--surface)}
@media (max-width:560px){.qds-row{grid-template-columns:1fr}}
.qds-btn{display:flex;gap:6px}
.qds-btn label{position:relative;font-weight:600;font-size:14px}
.qds-btn input{position:absolute;opacity:0;pointer-events:none}
.qds-btn span{display:inline-block;padding:7px 14px;border:1px solid var(--line);border-radius:999px;cursor:pointer;background:var(--paper)}
.qds-btn input:checked+span{background:var(--navy);color:var(--navy-ink);border-color:var(--navy)}
.qds-btn input:focus-visible+span{outline:2px solid var(--amber)}
.qkq{display:flex;gap:10px;align-items:center;margin:12px 0;max-width:340px}
.submitbar{position:sticky;bottom:0;display:flex;justify-content:space-between;align-items:center;gap:12px;padding:12px 14px;background:var(--surface);border:1px solid var(--line);border-radius:12px;box-shadow:0 -4px 16px rgba(0,0,0,.06)}
.result{text-align:center;padding:22px}.result .big{font-family:var(--display);font-size:56px;line-height:1;margin:0 0 8px;color:var(--navy)}
.result .big small{font-size:22px;color:var(--muted)}.result.pass .big{color:var(--leaf)}.result .row{justify-content:center}
.qchoices li.mine-ok{border-color:var(--leaf);background:var(--leaf-bg)}
.qchoices li.mine-bad{border-color:var(--warn);background:var(--warn-bg)}
.q.q-ok{border-left:4px solid var(--leaf)}.q.q-bad{border-left:4px solid var(--warn)}.q.q-part{border-left:4px solid var(--amber)}