:root {
  --ink: #15171c;
  --ink2: #3c414c;
  --ink3: #6b7180;
  --line: #e3e6ec;
  --bg: #fff;
  --soft: #f7f8fa;
  --brand: #0a6fd8;
  --brand-d: #0857ac;
  --brand-s: #e8f1fc;
  --ok: #0a8a4f;
  --ok-s: #e6f6ee;
  --no: #c62a2a;
  --no-s: #fdecec;
  --warn: #b45309;
  --warn-s: #fef4e3;
  --r: 12px;
  --maxw: 860px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, sans-serif;
  color: var(--ink);
  background: var(--soft);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}
h1, h2, h3 { margin: 0; font-weight: 600; line-height: 1.35; }
p { margin: 0; }
ul { margin: 0; padding: 0; list-style: none; }
a { color: inherit; text-decoration: none; }
button { font-family: inherit; }

.wrap { width: 100%; max-width: var(--maxw); margin: 0 auto; padding: 0 20px; }

/* header */
.hd { background: #fff; border-bottom: 1px solid var(--line); }
.hd-in { display: flex; align-items: center; justify-content: space-between; gap: 20px; padding: 14px 20px; flex-wrap: wrap; }
.brand { display: flex; align-items: center; gap: 11px; }
.mark {
  width: 42px; height: 42px; border-radius: 10px;
  background: var(--brand); color: #fff;
  display: flex; align-items: center; justify-content: center;
  font-size: 13px; font-weight: 700;
}
.bt { display: flex; flex-direction: column; line-height: 1.25; }
.bt strong { font-size: 15px; }
.bt span { font-size: 11px; color: var(--ink3); }

.hd-stat { display: flex; gap: 26px; }
.hs { text-align: center; }
.hs b { display: block; font-size: 19px; font-weight: 600; line-height: 1.2; }
.hs span { font-size: 11px; color: var(--ink3); }
.hs:nth-child(1) b { color: var(--ok); }
.hs:nth-child(2) b { color: var(--no); }
.hs:nth-child(3) b { color: var(--ink); }

/* tabs */
.tabs { background: #fff; border-bottom: 1px solid var(--line); position: sticky; top: 0; z-index: 20; }
.tabs-in { display: flex; align-items: center; gap: 8px; padding: 10px 20px; flex-wrap: wrap; }
.tab {
  background: none; border: 0; cursor: pointer;
  padding: 7px 14px; border-radius: 8px; font-size: 14px; color: var(--ink2);
  display: inline-flex; align-items: center; gap: 6px;
}
.tab:hover { background: var(--soft); }
.tab.active { background: var(--brand-s); color: var(--brand-d); font-weight: 500; }
.badge {
  background: var(--no); color: #fff; font-size: 11px;
  min-width: 17px; height: 17px; border-radius: 9px;
  display: inline-flex; align-items: center; justify-content: center; padding: 0 5px;
}
.tab.active .badge { background: var(--no); }
.spacer { flex: 1; }

.sel {
  padding: 7px 11px; border: 1px solid var(--line); border-radius: 8px;
  font-size: 13px; color: var(--ink2); background: #fff; cursor: pointer; font-family: inherit;
}
.sel:focus { outline: none; border-color: var(--brand); }

.btn {
  padding: 9px 18px; border-radius: 9px; border: 1px solid var(--line);
  background: #fff; color: var(--ink2); font-size: 14px; cursor: pointer;
  transition: all .16s;
}
.btn:hover:not(:disabled) { border-color: var(--brand); color: var(--brand); }
.btn:disabled { opacity: .4; cursor: not-allowed; }
.btn-sm { padding: 7px 13px; font-size: 13px; }
.btn-primary { background: var(--brand); border-color: var(--brand); color: #fff; }
.btn-primary:hover:not(:disabled) { background: var(--brand-d); color: #fff; }

/* main */
.main { padding: 22px 20px 60px; }

.progress-row { display: flex; align-items: center; gap: 14px; margin-bottom: 18px; }
.pbar { flex: 1; height: 7px; background: #e6e9ee; border-radius: 4px; overflow: hidden; }
.pfill { height: 100%; width: 0; background: linear-gradient(90deg, var(--brand), var(--ok)); border-radius: 4px; transition: width .3s; }
.ptext { font-size: 13px; color: var(--ink3); white-space: nowrap; }

/* card */
.card-box { min-height: 340px; }

.card {
  background: #fff; border: 1px solid var(--line); border-radius: var(--r);
  padding: 26px 28px; box-shadow: 0 2px 8px rgba(20, 23, 28, .04);
}
.card-top { display: flex; align-items: center; gap: 8px; margin-bottom: 18px; flex-wrap: wrap; }
.chip {
  font-size: 12px; padding: 4px 10px; border-radius: 6px;
  background: var(--brand-s); color: var(--brand-d); font-weight: 500;
}
.chip.t2 { background: var(--warn-s); color: var(--warn); }
.chip.idx { background: var(--soft); color: var(--ink3); font-variant-numeric: tabular-nums; }

.qtype-tag { font-size: 12px; padding: 4px 10px; border-radius: 6px; background: #eef1f5; color: var(--ink3); }
.qtype-tag.tfill { background: #eaf6ee; color: var(--ok); }
.qtype-tag.ttf { background: #fdf0e6; color: var(--warn); }

.stem { font-size: 19px; line-height: 1.75; margin-bottom: 22px; letter-spacing: .01em; }
.stem .blank {
  display: inline-block; min-width: 84px; border-bottom: 2px solid var(--brand);
  margin: 0 4px; vertical-align: baseline;
}

.answer-box {
  background: var(--ok-s); border: 1px solid #bfe6d0; border-radius: 10px;
  padding: 18px 20px; margin-bottom: 18px;
}
.answer-box.tf { background: var(--brand-s); border-color: #c3ddf7; }
.answer-box.wrong { background: var(--no-s); border-color: #f5c2c2; }
.ab-label { font-size: 12px; color: var(--ink3); margin-bottom: 6px; }
.ab-text { font-size: 17px; font-weight: 600; color: var(--ok); line-height: 1.6; word-break: break-word; }
.answer-box.tf .ab-text { color: var(--brand-d); }
.answer-box.wrong .ab-text { color: var(--no); }
.ab-hint { font-size: 12px; color: var(--ink3); margin-top: 8px; }

.self-rate { display: flex; gap: 10px; flex-wrap: wrap; margin-top: 6px; }
.sr {
  flex: 1; min-width: 120px; padding: 13px 14px; border-radius: 10px;
  border: 1.5px solid var(--line); background: #fff; cursor: pointer;
  display: flex; flex-direction: column; align-items: center; gap: 2px;
  transition: all .16s; font-size: 14px;
}
.sr small { font-size: 11px; color: var(--ink3); }
.sr.know:hover { border-color: var(--ok); background: var(--ok-s); color: var(--ok); }
.sr.vague:hover { border-color: var(--warn); background: var(--warn-s); color: var(--warn); }
.sr.dun:hover { border-color: var(--no); background: var(--no-s); color: var(--no); }
.sr .em { font-size: 18px; }

.card-nav { display: flex; justify-content: space-between; gap: 12px; margin-top: 20px; padding-top: 18px; border-top: 1px solid var(--line); }
.iconbtn {
  background: none; border: 0; cursor: pointer; font-size: 19px;
  padding: 6px 10px; border-radius: 8px; color: #d0d5dd;
}
.iconbtn:hover { background: var(--soft); color: var(--warn); }
.iconbtn.on { color: var(--warn); }

/* pager */
.pager { display: flex; align-items: center; justify-content: center; gap: 16px; margin: 20px 0 34px; }
.pinfo { font-size: 14px; color: var(--ink3); font-variant-numeric: tabular-nums; }

/* cat panel */
.cat-panel { background: #fff; border: 1px solid var(--line); border-radius: var(--r); padding: 24px 26px; }
.cat-panel h2 { font-size: 17px; margin-bottom: 4px; }
.cp-hint { font-size: 13px; color: var(--ink3); margin-bottom: 18px; }
.cat-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(210px, 1fr)); gap: 12px; }
.cat-item { background: var(--soft); border: 1px solid var(--line); border-radius: 10px; padding: 14px 16px; cursor: pointer; transition: all .16s; }
.cat-item:hover { border-color: var(--brand); background: var(--brand-s); }
.cat-item.active { border-color: var(--brand); background: var(--brand-s); }
.ci-name { font-size: 14px; font-weight: 500; margin-bottom: 6px; }
.ci-bar { height: 5px; background: #e2e5ea; border-radius: 3px; overflow: hidden; margin-bottom: 5px; }
.ci-fill { height: 100%; background: var(--ok); border-radius: 3px; transition: width .3s; }
.ci-num { font-size: 12px; color: var(--ink3); }

/* toast */
.toast {
  position: fixed; bottom: 28px; left: 50%; transform: translateX(-50%) translateY(20px);
  background: var(--ink); color: #fff; padding: 11px 20px; border-radius: 9px;
  font-size: 14px; opacity: 0; pointer-events: none; transition: all .24s; z-index: 100;
  max-width: 90vw; text-align: center;
}
.toast.show { opacity: 1; transform: translateX(-50%) translateY(0); }

/* responsive */
@media (max-width: 640px) {
  .hd-in { gap: 12px; }
  .hd-stat { gap: 18px; }
  .hs b { font-size: 16px; }
  .tabs-in { gap: 6px; }
  .tab { padding: 6px 11px; font-size: 13px; }
  .spacer { display: none; }
  .sel { flex: 1; min-width: 0; }
  .card { padding: 20px 18px; }
  .stem { font-size: 17px; }
  .self-rate { flex-direction: column; }
  .sr { flex-direction: row; justify-content: center; gap: 8px; align-items: baseline; }
  .main { padding: 16px 14px 44px; }
  .wrap { padding: 0 14px; }
}