/* ============ tokens ============ */
:root{
  --bg:#f7f8fa;
  --surface:#ffffff;
  --surface-2:#f2f4f7;
  --fg:#15181d;
  --fg-soft:#4b5462;
  --muted:#7a8494;
  --line:#e4e7ec;
  --line-soft:#eef0f4;
  --accent:#2f6fd0;
  --accent-fg:#ffffff;
  --accent-soft:#e8f0fc;
  --ok:#1a7f4b;
  --ok-soft:#e4f4ec;
  --warn:#b0651a;
  --warn-soft:#fdf0e3;
  --shadow:0 1px 2px rgba(16,24,40,.05), 0 4px 16px rgba(16,24,40,.05);
  --shadow-lg:0 2px 4px rgba(16,24,40,.06), 0 12px 32px rgba(16,24,40,.09);
  --r:14px;
  --font:"Microsoft JhengHei","微軟正黑體","Noto Sans TC",system-ui,-apple-system,sans-serif;
}
:root[data-theme="dark"], :root:not([data-theme="light"]) {
  color-scheme: light;
}
@media (prefers-color-scheme: dark){
  :root:not([data-theme="light"]){
    --bg:#0e1015;
    --surface:#161a21;
    --surface-2:#1c2129;
    --fg:#e9ecf1;
    --fg-soft:#bcc4d0;
    --muted:#8b95a5;
    --line:#262c36;
    --line-soft:#1f242c;
    --accent:#7aa9f0;
    --accent-fg:#0e1015;
    --accent-soft:#1b2634;
    --ok:#5cc48d;
    --ok-soft:#16281f;
    --warn:#e0a468;
    --warn-soft:#2a2015;
    --shadow:0 1px 2px rgba(0,0,0,.3), 0 4px 16px rgba(0,0,0,.25);
    --shadow-lg:0 2px 4px rgba(0,0,0,.35), 0 12px 32px rgba(0,0,0,.4);
    color-scheme: dark;
  }
}
:root[data-theme="dark"]{
  --bg:#0e1015; --surface:#161a21; --surface-2:#1c2129;
  --fg:#e9ecf1; --fg-soft:#bcc4d0; --muted:#8b95a5;
  --line:#262c36; --line-soft:#1f242c;
  --accent:#7aa9f0; --accent-fg:#0e1015; --accent-soft:#1b2634;
  --ok:#5cc48d; --ok-soft:#16281f; --warn:#e0a468; --warn-soft:#2a2015;
  --shadow:0 1px 2px rgba(0,0,0,.3), 0 4px 16px rgba(0,0,0,.25);
  --shadow-lg:0 2px 4px rgba(0,0,0,.35), 0 12px 32px rgba(0,0,0,.4);
  color-scheme: dark;
}

*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{
  margin:0;background:var(--bg);color:var(--fg);
  font-family:var(--font);font-size:16px;line-height:1.7;
  letter-spacing:.005em;
}
.wrap{max-width:960px;margin:0 auto;padding:0 22px}
.state{color:var(--muted);padding:60px 0;text-align:center}
button{font:inherit;color:inherit}

/* ============ topbar ============ */
.topbar{
  position:sticky;top:0;z-index:50;
  background:color-mix(in srgb, var(--surface) 88%, transparent);
  backdrop-filter:saturate(1.6) blur(12px);
  border-bottom:1px solid var(--line);
}
.topbar-in{display:flex;align-items:center;justify-content:space-between;height:58px}
.brand{display:flex;align-items:center;gap:11px;text-decoration:none;color:inherit}
.brand-mark{
  width:26px;height:26px;border-radius:8px;flex:none;
  background:linear-gradient(135deg,var(--accent),color-mix(in srgb,var(--accent) 55%, #9b6ef0));
  box-shadow:0 2px 8px color-mix(in srgb,var(--accent) 35%, transparent);
}
.brand-text{font-weight:800;letter-spacing:.02em;font-size:1.02rem}
.topbar-actions{display:flex;gap:6px}
.icon-btn{
  width:36px;height:36px;border-radius:10px;border:1px solid var(--line);
  background:var(--surface);cursor:pointer;font-size:1rem;line-height:1;
  display:grid;place-items:center;transition:background .15s,border-color .15s;
}
.icon-btn:hover{background:var(--surface-2);border-color:var(--muted)}

/* ============ subnav ============ */
.subnav{
  position:sticky;top:58px;z-index:40;
  background:var(--bg);border-bottom:1px solid var(--line-soft);
}
.subnav-in{display:flex;gap:6px;overflow-x:auto;padding:10px 22px;scrollbar-width:none}
.subnav-in::-webkit-scrollbar{display:none}
.chip{
  flex:none;padding:6px 14px;border-radius:999px;cursor:pointer;
  border:1px solid var(--line);background:var(--surface);
  font-size:.875rem;white-space:nowrap;transition:all .15s;
}
.chip:hover{border-color:var(--muted)}
.chip[aria-current="true"]{
  background:var(--accent);border-color:var(--accent);color:var(--accent-fg);font-weight:700;
}

/* ============ overview ============ */
.hero{padding:40px 0 26px}
.hero h1{margin:0 0 10px;font-size:1.75rem;line-height:1.35;letter-spacing:-.01em}
.hero p{margin:0;color:var(--fg-soft);max-width:60ch}
.stats{display:flex;flex-wrap:wrap;gap:26px;margin-top:22px;padding-top:20px;border-top:1px solid var(--line)}
.stat b{display:block;font-size:1.5rem;font-weight:800;line-height:1.2}
.stat span{font-size:.8rem;color:var(--muted)}

.grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(268px,1fr));gap:16px;padding-bottom:48px}
.card{
  display:block;text-align:left;width:100%;
  background:var(--surface);border:1px solid var(--line);border-radius:var(--r);
  padding:20px;cursor:pointer;box-shadow:var(--shadow);
  transition:transform .16s cubic-bezier(.2,.7,.3,1), box-shadow .16s, border-color .16s;
}
.card:hover{transform:translateY(-2px);box-shadow:var(--shadow-lg);border-color:color-mix(in srgb,var(--accent) 45%, var(--line))}
.card-top{display:flex;align-items:baseline;justify-content:space-between;gap:12px;margin-bottom:12px}
.card-name{font-size:1.15rem;font-weight:800;display:flex;align-items:center;gap:9px}
.dot{width:9px;height:9px;border-radius:50%;flex:none;background:var(--sc,var(--accent))}
.card-avg{font-size:1.3rem;font-weight:800;font-variant-numeric:tabular-nums}
.card-avg small{font-size:.7rem;font-weight:600;color:var(--muted);margin-left:2px}
.bar{height:6px;border-radius:99px;background:var(--surface-2);overflow:hidden;margin-bottom:14px}
.bar > i{display:block;height:100%;border-radius:99px;background:var(--sc,var(--accent))}
.card-meta{display:flex;gap:14px;font-size:.82rem;color:var(--muted)}
.card-meta b{color:var(--fg-soft);font-weight:700}

/* ============ subject ============ */
.shead{padding:34px 0 18px;display:flex;align-items:flex-end;justify-content:space-between;gap:18px;flex-wrap:wrap}
.shead h2{margin:0;font-size:1.55rem;letter-spacing:-.01em;display:flex;align-items:center;gap:11px}
.shead .dot{width:11px;height:11px}
.papers{display:flex;flex-wrap:wrap;gap:7px;padding-bottom:22px}
.paper{
  font-size:.78rem;padding:4px 11px;border-radius:8px;
  background:var(--surface-2);color:var(--fg-soft);border:1px solid var(--line-soft);
}
.paper b{font-variant-numeric:tabular-nums}

.weak{
  background:var(--surface);border:1px solid var(--line);border-radius:var(--r);
  margin-bottom:18px;box-shadow:var(--shadow);overflow:hidden;
}
.weak-head{padding:20px 22px 0}
.weak-title{margin:0;font-size:1.12rem;font-weight:800;display:flex;align-items:center;gap:10px;flex-wrap:wrap}
.tag{
  font-size:.72rem;font-weight:800;letter-spacing:.05em;padding:3px 9px;border-radius:6px;
  background:var(--sc-soft,var(--accent-soft));color:var(--sc,var(--accent));
}
.evi{
  margin:12px 0 0;padding:12px 15px;border-radius:10px;
  background:var(--surface-2);color:var(--fg-soft);font-size:.875rem;line-height:1.7;
}
.evi::before{content:"錯題依據　";font-weight:800;color:var(--muted);font-size:.78rem;letter-spacing:.04em}

.q{padding:22px;border-top:1px solid var(--line-soft);margin-top:20px}
.q:first-of-type{margin-top:18px}
.qhead{display:flex;align-items:center;gap:9px;flex-wrap:wrap;margin-bottom:12px}
.qno{
  width:25px;height:25px;border-radius:7px;flex:none;display:grid;place-items:center;
  background:var(--sc,var(--accent));color:var(--accent-fg);font-size:.8rem;font-weight:800;
}
.src{font-size:.83rem;font-weight:700}
.pill{
  font-size:.73rem;padding:2px 8px;border-radius:6px;
  border:1px solid var(--line);color:var(--muted);
}
.pill.d-易{color:var(--ok);border-color:color-mix(in srgb,var(--ok) 35%,transparent);background:var(--ok-soft)}
.pill.d-中{color:var(--warn);border-color:color-mix(in srgb,var(--warn) 35%,transparent);background:var(--warn-soft)}
.pill.d-難{color:#c2415a;border-color:#c2415a55;background:color-mix(in srgb,#c2415a 10%,transparent)}

.qbody{font-size:1rem;line-height:1.95;overflow-x:auto}
.qbody p{margin:0 0 .6em}
.qbody p:last-child{margin-bottom:0}
.qbody img{max-width:100%;height:auto;display:block;margin:12px 0;border-radius:8px;background:#fff}
.qbody math{font-size:1.05em}

/* ---- 作答選項 ---- */
.part + .part{margin-top:20px;padding-top:18px;border-top:1px dashed var(--line)}
.sub-no{
  font-size:.78rem;font-weight:800;letter-spacing:.05em;color:var(--sc,var(--accent));
  margin-bottom:8px;
}
.opts{display:grid;gap:8px;margin-top:14px}
.opt{
  display:flex;align-items:flex-start;gap:11px;width:100%;text-align:left;
  padding:11px 14px;border-radius:11px;cursor:pointer;
  border:1.5px solid var(--line);background:var(--surface);
  font-size:.96rem;line-height:1.7;
  transition:border-color .13s, background .13s, transform .08s;
}
.opt:hover:not(:disabled){border-color:var(--sc,var(--accent));background:var(--surface-2)}
.opt:active:not(:disabled){transform:scale(.995)}
.opt:disabled{cursor:default}
.opt-k{
  width:24px;height:24px;border-radius:7px;flex:none;margin-top:1px;
  display:grid;place-items:center;font-size:.8rem;font-weight:800;
  background:var(--surface-2);color:var(--muted);border:1px solid var(--line);
}
.opt-t{flex:1;min-width:0}
.opt-t img{max-width:100%;height:auto;border-radius:6px;background:#fff;margin:4px 0}
.opt.is-picked{border-color:var(--sc,var(--accent));background:var(--surface-2)}
.opt.is-picked .opt-k{background:var(--sc,var(--accent));color:#fff;border-color:transparent}
.opt.is-right{border-color:var(--ok);background:var(--ok-soft)}
.opt.is-right .opt-k{background:var(--ok);color:#fff;border-color:transparent}
.opt.is-wrong{border-color:#c2415a;background:color-mix(in srgb,#c2415a 10%,transparent)}
.opt.is-wrong .opt-k{background:#c2415a;color:#fff;border-color:transparent}
.opt-plain{display:inline-flex;width:auto;padding:9px 16px}
.opts:has(.opt-plain){grid-auto-flow:column;justify-content:start;gap:10px}
.hint{margin:9px 0 0;font-size:.8rem;color:var(--muted)}

.verdict{font-size:.79rem;font-weight:800;padding:2px 10px;border-radius:6px;margin-left:auto}
.verdict.ok{background:var(--ok-soft);color:var(--ok)}
.verdict.no{background:color-mix(in srgb,#c2415a 12%,transparent);color:#c2415a}

.freebox{margin-top:14px}
.freebox label{display:block;font-size:.8rem;font-weight:700;color:var(--muted);margin-bottom:6px}
.free{
  width:100%;padding:11px 13px;border-radius:11px;resize:vertical;
  border:1.5px solid var(--line);background:var(--surface-2);color:var(--fg);
  font-family:inherit;font-size:.94rem;line-height:1.7;
}
.free:focus{outline:none;border-color:var(--accent)}

.again{
  padding:7px 14px;border-radius:9px;cursor:pointer;font-size:.84rem;
  border:1px solid var(--line);background:var(--surface);color:var(--muted);
}
.again:hover{border-color:var(--muted)}

.qfoot{display:flex;align-items:center;gap:10px;margin-top:16px;flex-wrap:wrap}
.reveal{
  padding:7px 15px;border-radius:9px;cursor:pointer;font-size:.86rem;font-weight:700;
  border:1px solid var(--accent);background:transparent;color:var(--accent);
  transition:background .15s,color .15s;
}
.reveal:hover{background:var(--accent);color:var(--accent-fg)}
.mark{
  padding:7px 13px;border-radius:9px;cursor:pointer;font-size:.83rem;
  border:1px solid var(--line);background:var(--surface);color:var(--muted);transition:all .15s;
}
.mark:hover{border-color:var(--muted)}
.mark[aria-pressed="true"]{
  background:var(--ok-soft);border-color:color-mix(in srgb,var(--ok) 40%,transparent);
  color:var(--ok);font-weight:700;
}

.ans{margin-top:14px;border-radius:11px;overflow:hidden;border:1px solid var(--line)}
.ans-key{
  padding:9px 15px;background:var(--ok-soft);color:var(--ok);
  font-weight:800;font-size:.92rem;border-bottom:1px solid var(--line);
}
.ans-body{padding:15px;font-size:.93rem;line-height:1.9;background:var(--surface-2)}
.ans-body b{color:var(--fg)}
.q:not(.open) .ans{display:none}

/* ============ foot ============ */
.foot{border-top:1px solid var(--line);margin-top:30px;padding:22px 0 44px}
.foot p{margin:0 0 4px;color:var(--muted);font-size:.79rem}

/* ============ print ============ */
.print-only{display:none}
@media print{
  @page{ size:A4; margin:16mm 15mm; }
  html,body{background:#fff;color:#000}
  body{
    font-family:"微軟正黑體","Microsoft JhengHei",sans-serif;
    font-size:14pt;font-weight:700;line-height:1.85;
  }
  .no-print{display:none !important}
  .print-only{display:block}
  .print-head{margin-bottom:8mm;border-bottom:2pt solid #000;padding-bottom:3mm}
  .print-head h1{margin:0;font-size:18pt}
  .print-head p{margin:2mm 0 0;font-size:11pt;font-weight:400}
  .wrap{max-width:none;padding:0}
  .hero,.stats,.grid,.papers{display:none}
  .shead{padding:0 0 4mm}
  .shead h2{font-size:16pt}
  .weak{border:0;border-radius:0;box-shadow:none;margin:0 0 8mm;break-inside:auto}
  .weak-head{padding:0}
  .weak-title{font-size:14pt;border-bottom:1.5pt solid #000;padding-bottom:2mm}
  .tag{border:1pt solid #000;background:transparent;color:#000}
  .evi{background:transparent;border-left:2pt solid #000;border-radius:0;font-size:11pt;font-weight:400;padding:2mm 0 2mm 4mm}
  .q{break-inside:avoid;border-top:0;padding:5mm 0 0;margin:0}
  .qno{background:#000;color:#fff}
  .pill{border:1pt solid #000;color:#000;background:transparent}
  .qbody{font-size:14pt}
  .qbody img{max-width:70%}
  .qfoot,.hint,.verdict{display:none}
  /* 列印時選項印成純文字清單，不要按鈕外框 */
  .opts{display:block;margin-top:2mm}
  .opt{
    display:block;width:auto;border:0 !important;background:transparent !important;
    padding:0 0 1mm;font-size:14pt;font-weight:700;
  }
  .opt-k{
    display:inline;width:auto;height:auto;border:0;background:transparent !important;
    color:#000 !important;font-size:14pt;
  }
  .opt-k::before{content:"("}
  .opt-k::after{content:") "}
  .opt-t{display:inline}
  .part + .part{border-top:1pt dashed #000;margin-top:4mm;padding-top:3mm}
  .sub-no{color:#000;font-size:12pt}
  .freebox label{color:#000;font-size:12pt}
  .free{border:1pt solid #000;background:transparent;min-height:28mm}
  .q .ans{display:block !important;border:1pt dashed #000;margin-top:4mm}
  .ans-key{background:transparent;color:#000;border-bottom:1pt dashed #000}
  .ans-body{background:transparent;font-size:12pt;font-weight:400}
  body.print-no-ans .ans{display:none !important}
}