:root {
  --bg: #f6f3ec;
  --card: #ffffff;
  --ink: #1f2328;
  --muted: #6b6f76;
  --line: #e3ddd0;
  --accent: #2f6f5e;
  --accent-soft: #e3f0eb;
  --pre: #8a8f98;
  --ok: #1f8a4c;
  --ok-soft: #e4f4ea;
  --bad: #c0392b;
  --bad-soft: #fbe9e7;
  --sel: #2f6f5e;
  --box: #faf7ef;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #15171a;
    --card: #1e2125;
    --ink: #e7e9ec;
    --muted: #9aa0a8;
    --line: #33373d;
    --accent: #6cc3a6;
    --accent-soft: #1f3530;
    --pre: #7d838c;
    --ok: #5fd08d;
    --ok-soft: #1c3326;
    --bad: #ff7b6b;
    --bad-soft: #3a2220;
    --sel: #6cc3a6;
    --box: #23262b;
  }
}
:root[data-theme="dark"] {
  --bg: #15171a; --card: #1e2125; --ink: #e7e9ec; --muted: #9aa0a8; --line: #33373d;
  --accent: #6cc3a6; --accent-soft: #1f3530; --pre: #7d838c; --ok: #5fd08d; --ok-soft: #1c3326;
  --bad: #ff7b6b; --bad-soft: #3a2220; --sel: #6cc3a6; --box: #23262b;
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0; background: var(--bg); color: var(--ink);
  font: 17px/1.65 -apple-system, BlinkMacSystemFont, "PingFang SC", "Helvetica Neue", "Microsoft YaHei", sans-serif;
}
a { color: var(--accent); }
.topbar {
  position: sticky; top: 0; z-index: 10; display: flex; align-items: center; justify-content: space-between;
  padding: 10px 16px; background: var(--bg); border-bottom: 1px solid var(--line);
}
.brand { font-weight: 700; text-decoration: none; color: var(--ink); }
.topbar nav a { margin-left: 16px; text-decoration: none; font-size: 15px; }
main { max-width: 760px; margin: 0 auto; padding: 16px 16px 120px; }
.muted { color: var(--muted); }
.small { font-size: 14px; }
h1 { font-size: 22px; margin: 8px 0 4px; }
h2 { font-size: 19px; margin: 28px 0 8px; padding-bottom: 6px; border-bottom: 2px solid var(--accent); }
.card { background: var(--card); border: 1px solid var(--line); border-radius: 12px; padding: 14px 16px; margin: 12px 0; }
.set-card { display: block; text-decoration: none; color: inherit; }
.set-card .row { display: flex; justify-content: space-between; align-items: baseline; gap: 8px; }
.set-card .title { font-size: 18px; font-weight: 700; }
.chips { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 6px; }
.chip { font-size: 13px; padding: 1px 8px; border-radius: 99px; background: var(--accent-soft); color: var(--accent); }
.name-row { display: flex; gap: 8px; align-items: center; }
.name-row span { white-space: nowrap; }
.name-row input { flex: 1; }
input[type=text], textarea {
  font: inherit; color: var(--ink); background: var(--card); border: 1px solid var(--line); border-radius: 8px; padding: 6px 10px;
}
textarea { width: 100%; min-height: 84px; }
.directions { font-size: 14px; color: var(--muted); margin: 0 0 8px; }
.unit-head { display: flex; justify-content: space-between; align-items: baseline; gap: 8px; }
.src { font-size: 13px; color: var(--muted); }
.heading { font-weight: 700; text-align: center; margin: 4px 0 8px; }
.passage p { margin: 0 0 10px; text-align: left; }
.passage table { border-collapse: collapse; margin: 6px 0 12px; font-size: 15px; width: 100%; }
.passage td { border: 1px solid var(--line); padding: 4px 6px; }
.passage img, .qimg { max-width: 100%; height: auto; border-radius: 6px; border: 1px solid var(--line); background: #fff; }
.pre { color: var(--pre); border-bottom: 1px dashed var(--pre); }
.pre .num, .blank .num { font-size: 13px; }
.blank { color: var(--accent); font-weight: 600; white-space: nowrap; cursor: pointer; }
.blank .fill { display: inline-block; min-width: 3.5em; border-bottom: 2px solid var(--accent); text-align: center; padding: 0 2px; white-space: normal; }
.blank.ok .fill { color: var(--ok); border-color: var(--ok); }
.blank.bad .fill { color: var(--bad); border-color: var(--bad); }
input.blank-input {
  width: 8.5em; font: inherit; font-weight: 600; color: var(--accent); border: none; border-bottom: 2px solid var(--accent);
  background: var(--accent-soft); border-radius: 4px 4px 0 0; padding: 0 4px; margin: 0 2px;
}
input.blank-input.ok { color: var(--ok); border-color: var(--ok); background: var(--ok-soft); }
input.blank-input.bad { color: var(--bad); border-color: var(--bad); background: var(--bad-soft); }
.option-box { border: 1.5px solid var(--line); border-radius: 8px; padding: 10px 14px; margin: 8px 0 14px; background: var(--box); font-size: 15px; }
.option-box .box-title { font-weight: 700; font-size: 13px; color: var(--muted); }
.option-box.words { display: flex; flex-wrap: wrap; gap: 4px 14px; }
.option-box.sentences div { margin: 4px 0; }
.q { border-top: 1px dashed var(--line); padding: 12px 0 4px; }
.q:first-of-type { border-top: none; }
.q-stem { margin-bottom: 8px; }
.q-num { display: inline-block; min-width: 2.4em; font-weight: 700; color: var(--accent); }
.opts { display: grid; gap: 6px; }
.opts.wrap { display: flex; flex-wrap: wrap; }
.opt {
  font: inherit; font-size: 16px; text-align: left; color: var(--ink); background: var(--card);
  border: 1.5px solid var(--line); border-radius: 10px; padding: 8px 12px; cursor: pointer; line-height: 1.4;
}
.opts.wrap .opt { padding: 6px 10px; font-size: 15px; }
.opt .l { font-weight: 700; margin-right: 6px; }
.opt.sel { border-color: var(--sel); background: var(--accent-soft); }
.opt.is-answer { border-color: var(--ok); background: var(--ok-soft); }
.opt.is-wrong { border-color: var(--bad); background: var(--bad-soft); }
.opt:disabled { cursor: default; }
.verdict { margin-top: 8px; font-size: 15px; }
.verdict .ok { color: var(--ok); font-weight: 700; }
.verdict .bad { color: var(--bad); font-weight: 700; }
details.explain { margin-top: 6px; font-size: 15px; background: var(--box); border-radius: 8px; padding: 6px 10px; }
details.explain summary { cursor: pointer; color: var(--accent); }
.ex-item { margin: 8px 0; }
.ex-label { font-weight: 700; font-size: 13px; color: var(--muted); }
.ex-item p { margin: 2px 0; }
.ex-item ol, .ex-item ul { margin: 2px 0; padding-left: 1.4em; }
.ex-item code { font-size: 14px; background: var(--accent-soft); padding: 0 3px; border-radius: 3px; }
.ex-item table { border-collapse: collapse; font-size: 14px; }
.ex-item td, .ex-item th { border: 1px solid var(--line); padding: 2px 6px; }
.zh { font-size: 17px; }
.kw { color: var(--accent); font-weight: 600; }
.submitbar {
  position: fixed; left: 0; right: 0; bottom: 0; z-index: 10; display: flex; gap: 10px; align-items: center; justify-content: space-between;
  padding: 10px 16px calc(10px + env(safe-area-inset-bottom)); background: var(--card); border-top: 1px solid var(--line);
}
.btn {
  font: inherit; font-weight: 700; border: none; border-radius: 10px; padding: 10px 18px; cursor: pointer;
  background: var(--accent); color: #fff; text-decoration: none; display: inline-block;
}
.btn.ghost { background: transparent; color: var(--accent); border: 1.5px solid var(--accent); }
.scorecard { text-align: center; }
.scorecard .big { font-size: 40px; font-weight: 800; color: var(--accent); }
.toggle { display: flex; gap: 8px; justify-content: center; flex-wrap: wrap; margin-top: 8px; }
.hide-correct .unit.all-correct, .hide-correct .q.correct { display: none; }
.toast { position: fixed; left: 50%; bottom: 84px; transform: translateX(-50%); background: var(--ink); color: var(--bg); padding: 8px 14px; border-radius: 8px; font-size: 14px; z-index: 20; }
.res-row { display: flex; justify-content: space-between; gap: 8px; text-decoration: none; color: inherit; }
.ex-note { border-left: 3px solid var(--bad); padding-left: 8px; }
.ex-note .ex-label { color: var(--bad); }
.option-box .used, .opt.used { text-decoration: line-through; opacity: 0.45; }
.report { font-size: 16px; }
.report h2 { font-size: 18px; }
.report h3 { font-size: 16px; margin: 18px 0 6px; }
.report table { border-collapse: collapse; width: 100%; font-size: 14px; display: block; overflow-x: auto; margin: 8px 0 14px; }
.report th, .report td { border: 1px solid var(--line); padding: 4px 6px; text-align: left; vertical-align: top; }
.report th { background: var(--box); }
.report code { font-size: 13px; background: var(--accent-soft); padding: 0 3px; border-radius: 3px; word-break: break-word; }
.report ul, .report ol { padding-left: 1.3em; }
.report td:first-child, .report th:first-child { white-space: nowrap; }
.report li { margin-bottom: 8px; }
.name-row input { min-width: 0; }
.name-row .btn { flex-shrink: 0; }