/* Layout concept: an exchange-style board. Sticky top bar with search, text tabs by subject,
   a large mastery chart then topic cards grouped by area that each
   show a big mastery number, a sparkline and two actions. The quiz is a focused single column. */
:root{
  --bg:#F3F7F8;
  --surface:#FFFFFF;
  --line:#E1E8EB;
  --line-strong:#C3CFD5;
  --fg:#0D1A23;
  --muted:#5B6F7C;
  --pos:#087A56;
  --pos-fill:#28CC95;
  --pos-tint:#E0F6EC;
  --pos-ink:#04271D;
  --alt:#1F55C9;
  --alt-tint:#E4ECFC;
  --neg:#CF2F4A;
  --neg-tint:#FCE8EC;
  --shadow:0 1px 2px rgba(13,26,35,.05),0 6px 20px rgba(13,26,35,.05);
  --font:'Figtree','Noto Sans SC','PingFang SC','Microsoft YaHei',system-ui,-apple-system,'Segoe UI',sans-serif;
}
@media (prefers-color-scheme: dark){
  :root:not([data-theme="light"]){
    --bg:#091117;--surface:#101B23;--line:#1F2E39;--line-strong:#33485A;--fg:#E7EEF2;--muted:#8CA0AD;
    --pos:#2FD6A0;--pos-fill:#28CC95;--pos-tint:rgba(40,204,149,.14);--pos-ink:#04271D;
    --alt:#7FA6FF;--alt-tint:rgba(127,166,255,.14);--neg:#FF7389;--neg-tint:rgba(255,115,137,.14);
    --shadow:0 1px 2px rgba(0,0,0,.3);color-scheme:dark;
  }
}
:root[data-theme="dark"]{
  --bg:#091117;--surface:#101B23;--line:#1F2E39;--line-strong:#33485A;--fg:#E7EEF2;--muted:#8CA0AD;
  --pos:#2FD6A0;--pos-fill:#28CC95;--pos-tint:rgba(40,204,149,.14);--pos-ink:#04271D;
  --alt:#7FA6FF;--alt-tint:rgba(127,166,255,.14);--neg:#FF7389;--neg-tint:rgba(255,115,137,.14);
  --shadow:0 1px 2px rgba(0,0,0,.3);color-scheme:dark;
}

*{box-sizing:border-box}
body{background:var(--bg);color:var(--fg);font-family:var(--font);font-size:15px;line-height:1.5;-webkit-font-smoothing:antialiased}
body::before{content:"";position:fixed;inset:0 0 auto;height:env(safe-area-inset-top,0px);z-index:30;background:var(--surface)}
button,input{font-family:inherit}
:focus-visible{outline:2px solid var(--alt);outline-offset:2px}
.sr{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap}
.wrap{max-width:1180px;margin:0 auto;padding-left:max(16px,env(safe-area-inset-left,0px));padding-right:max(16px,env(safe-area-inset-right,0px))}
.pad{padding-block:24px 8px}

/* top bar */
.top{position:sticky;top:env(safe-area-inset-top,0px);z-index:20;background:var(--surface);border-bottom:1px solid var(--line)}
.bar{display:flex;align-items:center;flex-wrap:wrap;gap:12px 16px;padding-block:12px 4px}
.brand{display:flex;align-items:center;gap:9px;color:var(--fg);text-decoration:none;font-weight:800;font-size:19px;letter-spacing:-.02em;margin-right:auto}
.search{order:3;flex:1 1 100%;position:relative;min-width:0}
.search svg{position:absolute;left:13px;top:50%;transform:translateY(-50%);color:var(--muted)}
.search input{width:100%;height:42px;border-radius:999px;border:1px solid transparent;background:var(--bg);padding:0 16px 0 40px;font-size:15px;color:var(--fg)}
.search input::placeholder{color:var(--muted)}
.search input:focus{border-color:var(--alt);outline:none}
.icon-btn{width:40px;height:40px;border-radius:999px;border:1px solid var(--line);background:var(--surface);color:var(--fg);display:grid;place-items:center;cursor:pointer}
.icon-btn:hover{border-color:var(--line-strong)}
@media (min-width:700px){
  .search{order:0;flex:0 1 460px;margin-right:auto}
  .brand{margin-right:0}
  .bar{flex-wrap:nowrap;padding-block:12px 0}
}
.tabs{display:flex;gap:2px;overflow-x:auto;scrollbar-width:none}
.tabs::-webkit-scrollbar{display:none}
.tab{background:none;border:0;border-bottom:2px solid transparent;padding:12px 12px 10px;font-weight:600;font-size:15px;color:var(--muted);white-space:nowrap;cursor:pointer}
.tab:hover{color:var(--fg)}
.tab[aria-pressed="true"]{color:var(--fg);border-bottom-color:var(--fg)}

/* shared bits */
.card{background:var(--surface);border:1px solid var(--line);border-radius:12px}
.eyebrow{font-size:12px;font-weight:700;letter-spacing:.06em;text-transform:uppercase;color:var(--muted)}
.chip{display:inline-flex;align-items:center;padding:2px 8px;border-radius:999px;background:var(--bg);color:var(--muted);font-size:11px;font-weight:700;letter-spacing:.04em;text-transform:uppercase}
.chip.sample{background:var(--alt-tint);color:var(--alt)}
.pct{font-size:.55em;font-weight:700;margin-left:2px;color:var(--muted)}
.delta{display:inline-flex;align-items:center;gap:3px;font-weight:700;font-size:14px;font-variant-numeric:tabular-nums}
.delta.up{color:var(--pos)}.delta.down{color:var(--neg)}.delta.flat{color:var(--muted)}
.btn{height:40px;padding:0 16px;border-radius:8px;border:0;font-weight:700;font-size:14px;cursor:pointer;transition:background .15s,color .15s}
.btn.go{background:var(--pos-tint);color:var(--pos)}
.btn.go:hover{background:var(--pos-fill);color:var(--pos-ink)}
.btn.quick{background:var(--alt-tint);color:var(--alt)}
.btn.quick:hover{background:var(--alt);color:var(--surface)}
.btn.solid{background:var(--pos-fill);color:var(--pos-ink)}
.btn.solid:hover{filter:brightness(.95)}
.btn:disabled{opacity:.45;cursor:not-allowed}
.btn.wide{width:100%}
.link{background:none;border:0;padding:4px 0;color:var(--alt);font-weight:600;font-size:14px;cursor:pointer}
.link:hover{text-decoration:underline}

/* hero */
.chartcard{padding:20px}
.chead{display:flex;justify-content:space-between;align-items:flex-start;flex-wrap:wrap;gap:12px}
.eyebrow-row{display:flex;align-items:center;flex-wrap:wrap;gap:8px}
.bignum{display:flex;align-items:baseline;flex-wrap:wrap;gap:4px 12px;font-size:46px;font-weight:800;letter-spacing:-.03em;line-height:1.1;font-variant-numeric:tabular-nums;margin-top:6px}
.bignum .delta{font-size:15px;letter-spacing:0}
.sub{color:var(--muted);font-size:14px;margin-top:2px}
.ranges{display:flex;gap:2px;background:var(--bg);padding:3px;border-radius:10px}
.rbtn{border:0;background:none;padding:6px 12px;border-radius:8px;font-weight:700;font-size:13px;color:var(--muted);cursor:pointer}
.rbtn[aria-pressed="true"]{background:var(--surface);color:var(--fg);box-shadow:var(--shadow)}
.chartwrap{position:relative;margin-top:14px;min-height:200px}
.chart{display:block;touch-action:pan-y;overflow:visible}
.chart .grid{stroke:var(--line);stroke-dasharray:3 4;stroke-width:1}
.chart .ax{fill:var(--muted);font-size:11px;font-family:var(--font)}
.chart .ln{stroke:var(--pos-fill);stroke-width:2.5;stroke-linejoin:round;stroke-linecap:round;fill:none}
.chart .s0{stop-color:var(--pos-fill);stop-opacity:.26}
.chart .s1{stop-color:var(--pos-fill);stop-opacity:0}
.chart .dot{fill:var(--pos-fill);stroke:var(--surface);stroke-width:2}
.chart .halo{fill:var(--pos-fill);opacity:.22}
.chart .cross{stroke:var(--muted);stroke-dasharray:3 3}
.chart.down .ln{stroke:var(--neg)}
.chart.down .s0,.chart.down .s1{stop-color:var(--neg)}
.chart.down .dot,.chart.down .halo{fill:var(--neg)}
.tip{position:absolute;pointer-events:none;transform:translate(-50%,-100%);background:var(--fg);color:var(--surface);padding:7px 10px;border-radius:8px;font-size:12px;line-height:1.35;white-space:nowrap;z-index:2}
.tip span{opacity:.75}
.empty{display:grid;place-items:center;min-height:200px;text-align:center;color:var(--muted);border:1px dashed var(--line-strong);border-radius:10px;padding:16px}

/* topic grid */
.sec-head{display:flex;align-items:baseline;justify-content:space-between;gap:12px;margin:28px 0 12px}
.sec-head h2{margin:0;font-size:20px;font-weight:800;letter-spacing:-.02em}
.sec-head span{color:var(--muted);font-size:14px}
.areas{display:grid;gap:32px}
.area-head{display:flex;align-items:baseline;gap:10px;margin-bottom:12px}
.area-head h3{margin:0;font-size:17px;font-weight:800;letter-spacing:-.01em}
.area-head span{color:var(--muted);font-size:13px}
.cards{display:grid;grid-template-columns:repeat(auto-fill,minmax(min(100%,290px),1fr));gap:16px}
.tcard{padding:16px;display:flex;flex-direction:column;gap:12px;min-width:0;transition:border-color .15s,box-shadow .15s}
.tcard:hover{border-color:var(--line-strong);box-shadow:var(--shadow)}
.trow{display:flex;align-items:center;justify-content:space-between;gap:8px;min-height:22px}
.tq{margin:0;font-size:17px;line-height:1.3;font-weight:700;letter-spacing:-.01em;text-wrap:balance}
.tmid{display:flex;align-items:flex-end;justify-content:space-between;gap:12px}
.tnum{font-size:34px;font-weight:800;letter-spacing:-.03em;line-height:1.1;font-variant-numeric:tabular-nums}
.tlabel{display:flex;align-items:center;gap:8px;color:var(--muted);font-size:13px;font-weight:600}
.spark{flex:none;width:110px;height:40px}
.spark .ln{stroke:var(--pos-fill);stroke-width:2;fill:none;stroke-linejoin:round;stroke-linecap:round}
.spark .end{fill:var(--pos-fill)}
.spark.down .ln{stroke:var(--neg)}.spark.down .end{fill:var(--neg)}
.spark .none{stroke:var(--line-strong);stroke-width:2;stroke-dasharray:3 4;fill:none}
.tmeta{color:var(--muted);font-size:13px}
.tact{display:grid;grid-template-columns:1fr 1fr;gap:8px;margin-top:auto}

/* Quiz / Downloads sub-tabs */
.levels,#levels{margin-top:24px}
.subtabs{display:inline-flex;gap:2px;background:var(--surface);border:1px solid var(--line);padding:3px;border-radius:10px}
.subtab{border:0;background:none;padding:7px 16px;border-radius:8px;font-weight:700;font-size:14px;color:var(--muted);cursor:pointer}
.subtab:hover{color:var(--fg)}
.subtab[aria-pressed="true"]{background:var(--bg);color:var(--fg);box-shadow:var(--shadow)}

/* section menu (Quiz / Downloads) in a column on the left, content on the right */
.split{margin-top:24px;display:flex;flex-direction:column}
.content{min-width:0}
#quizView>.sec-head,#downloads>.sec-head{margin-top:0}
.sidenav{order:-1;display:flex;gap:8px;overflow-x:auto;scrollbar-width:none;margin-bottom:16px}
.sidenav::-webkit-scrollbar{display:none}
.navitem{display:flex;align-items:center;justify-content:space-between;gap:12px;flex:none;padding:10px 14px;border:1px solid var(--line);border-radius:10px;background:var(--surface);color:var(--muted);font-weight:700;font-size:15px;cursor:pointer;text-align:left}
.navitem:hover{color:var(--fg);border-color:var(--line-strong)}
.navitem[aria-pressed="true"]{background:var(--alt-tint);border-color:transparent;color:var(--alt)}
.navcount{min-width:22px;padding:1px 7px;border-radius:999px;background:var(--bg);color:var(--muted);font-size:12px;font-weight:700;text-align:center;font-variant-numeric:tabular-nums}
.navitem[aria-pressed="true"] .navcount{background:var(--surface);color:var(--alt)}
@media (min-width:900px){
  .split.has-side{display:grid;grid-template-columns:220px minmax(0,1fr);gap:32px;align-items:start}
  .split.has-side .sidenav{order:-1;flex-direction:column;overflow:visible;margin:0;position:sticky;top:120px;padding:8px;background:var(--surface);border:1px solid var(--line);border-radius:12px;gap:2px}
  .split.has-side .navitem{border:0;background:none;width:100%;border-radius:8px}
  .split.has-side .navitem:hover{background:var(--bg)}
  .split.has-side .navitem[aria-pressed="true"]{background:var(--alt-tint)}
}

/* downloads: one table per level */
.dl-group{padding:16px}
.dl-scroll{overflow-x:auto}
.dl-table{width:100%;border-collapse:collapse;font-size:14px}
.dl-table th,.dl-table td{padding:10px 8px;text-align:left;vertical-align:middle;border-top:1px solid var(--line)}
.dl-table thead th{border-top:0;padding-top:0;font-size:12px;font-weight:700;letter-spacing:.06em;text-transform:uppercase;color:var(--muted);white-space:nowrap}
.dl-table tbody th{font-weight:800;white-space:nowrap;border-right:1px solid var(--line)}
.dl-table tbody td{width:38%}
.dl-link{display:inline-flex;align-items:center;gap:6px;color:var(--alt);font-weight:600;text-decoration:none;line-height:1.3}
.dl-link:hover{text-decoration:underline}
.dl-link svg{flex:none}
.dl-none{color:var(--muted)}
}
.nores{grid-column:1/-1;text-align:center;color:var(--muted);padding:40px 16px}

/* quiz */
.qwrap{max-width:680px;margin:0 auto}
.qtop{display:flex;justify-content:space-between;align-items:center;gap:12px;margin-bottom:12px}
.segs{display:flex;gap:4px;margin-bottom:22px}
.seg{flex:1;height:4px;border-radius:2px;background:var(--line)}
.seg.cur{background:var(--fg)}
.seg.done-ok{background:var(--pos-fill)}
.seg.done-bad{background:var(--neg)}
.qtext{margin:0 0 18px;font-size:24px;line-height:1.3;font-weight:700;letter-spacing:-.015em;text-wrap:pretty}
.qtext:focus{outline:none}
.blank{display:inline-block;width:3.2em;border-bottom:2px solid var(--fg);vertical-align:baseline;margin:0 2px}
.opts{display:grid;gap:10px}
.opt{display:flex;gap:12px;align-items:flex-start;width:100%;text-align:left;padding:14px 16px;background:var(--surface);border:1px solid var(--line);border-radius:12px;font-size:16px;font-weight:500;color:var(--fg);cursor:pointer;transition:border-color .12s,background .12s}
.opt:hover:not(:disabled){border-color:var(--alt)}
.opt:disabled{cursor:default;color:var(--fg)}
.opt .key{flex:none;width:26px;height:26px;border-radius:8px;background:var(--bg);display:grid;place-items:center;font-size:12px;font-weight:700;color:var(--muted)}
.opt.ok{border-color:var(--pos);background:var(--pos-tint)}
.opt.bad{border-color:var(--neg);background:var(--neg-tint)}
.opt.ok .key{background:var(--pos-fill);color:var(--pos-ink)}
.opt.bad .key{background:var(--neg);color:var(--surface)}
.opt>span:last-child{min-width:0;padding-top:2px}
.fb{border-radius:12px;padding:14px 16px;margin-top:14px;line-height:1.5}
.fb.ok{background:var(--pos-tint)}.fb.bad{background:var(--neg-tint)}
.fb strong{font-weight:800}
.qfoot{display:flex;justify-content:space-between;align-items:center;gap:12px;flex-wrap:wrap;margin-top:18px}
.hint{color:var(--muted);font-size:13px}

.res{padding:28px 24px;text-align:center}
.res h2{margin:6px 0 0;font-size:22px;font-weight:800;letter-spacing:-.02em}
.score{font-size:68px;font-weight:800;letter-spacing:-.04em;line-height:1.05;font-variant-numeric:tabular-nums;margin-top:8px}
.score small{font-size:.35em;color:var(--muted);font-weight:700;letter-spacing:0;margin-left:6px}
.mline{display:inline-flex;flex-wrap:wrap;justify-content:center;gap:4px 10px;align-items:center;color:var(--muted);font-weight:600;margin-top:6px}
.mline b{color:var(--fg);font-variant-numeric:tabular-nums}
.res-act{display:grid;grid-template-columns:1fr 1fr;gap:10px;margin-top:22px}
.miss{margin-top:16px;display:grid;gap:12px}
.miss article{padding:16px;text-align:left}
.miss h3{margin:0 0 8px;font-size:16px;line-height:1.35;font-weight:700}
.miss p{margin:2px 0;font-size:14px}
.miss .yours{color:var(--neg)}.miss .right{color:var(--pos);font-weight:600}
.miss .why{color:var(--muted)}

.foot{color:var(--muted);font-size:13px;padding-block:28px 40px}
.foot p{margin:0 0 8px}
.reset-confirm{display:flex;flex-wrap:wrap;align-items:center;gap:8px 12px;color:var(--fg);font-weight:600}
.btn.sm{height:34px;padding:0 14px}
.btn.danger{background:var(--neg-tint);color:var(--neg)}
.btn.danger:hover{background:var(--neg);color:var(--surface)}
.note{color:var(--muted);margin-left:10px}

@media (max-width:480px){
  .bignum{font-size:40px}
  .qtext{font-size:21px}
  .res-act{grid-template-columns:1fr}
}
@media (prefers-reduced-motion:reduce){*{transition:none!important;animation:none!important}}

/* Oral (Paper 4) intro */
#oral>.sec-head{margin-top:0}
.oral{padding:22px}
.oral-lead{margin:0 0 18px;line-height:1.6}
.oral-parts{display:grid;gap:14px}
.oral-part{border:1px solid var(--line,#e3e8ea);border-radius:12px;padding:16px}
.oral-part h3{margin:4px 0 6px;font-size:16px}
.oral-part p{margin:0;line-height:1.55}
.oral-marks{font-size:12px;font-weight:700;letter-spacing:.04em;text-transform:uppercase;opacity:.7}
@media (min-width:700px){.oral-parts{grid-template-columns:1fr 1fr}}
.navnote{display:block;font-size:12px;font-weight:500;opacity:.8;margin-top:2px}