:root {
  --paper: #f3eee4;
  --sheet: #fffdf8;
  --ink: #1c2a2b;
  --muted: #5d6b6c;
  --line: #d8cfc0;
  --pine: #1f5a4e;
  --pine-2: #2f7a69;
  --clay: #c45c26;
  --gold: #b0892a;
  --good: #1d6b4a;
  --bad: #a33b2b;
  --serif: "Source Han Serif SC", "Noto Serif SC", "Songti SC", serif;
  --sans: "Noto Sans CJK SC", "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
}
* { box-sizing: border-box; }
html, body { margin: 0; min-height: 100%; }
body {
  font-family: var(--sans);
  color: var(--ink);
  background:
    radial-gradient(900px 420px at 8% -8%, #efe4c8 0%, transparent 45%),
    linear-gradient(180deg, #f7f2e8, var(--paper));
  line-height: 1.65;
}
button, input, textarea, select { font: inherit; color: inherit; }
button { cursor: pointer; }
#app { min-height: 100vh; }

.login {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 24px;
}
.login-card {
  width: min(420px, 100%);
  background: var(--sheet);
  border: 1px solid var(--line);
  border-radius: 18px;
  padding: 32px 28px;
  box-shadow: 0 16px 40px rgba(28,42,43,.08);
}
.login-card h1 { font-family: var(--serif); margin: 0 0 8px; }
.hint { color: var(--muted); font-size: 13px; }
label { display: block; margin: 14px 0 6px; font-size: 13px; color: var(--muted); }
input, textarea, select {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 10px 12px;
  background: #fff;
}
textarea { min-height: 140px; resize: vertical; }

.shell { display: grid; grid-template-columns: 260px 1fr; min-height: 100vh; }
.rail {
  background: #142422;
  color: #e8efe8;
  padding: 22px 16px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}
.brand { font-family: var(--serif); font-size: 26px; letter-spacing: .08em; }
.brand small { display: block; color: #9bb0a8; font-size: 12px; font-family: var(--sans); letter-spacing: 0; margin-top: 6px; }
.rail button {
  border: 0;
  background: transparent;
  color: #d7e4dc;
  text-align: left;
  padding: 9px 10px;
  border-radius: 8px;
}
.rail button.active, .rail button:hover { background: #24463d; }
.rail-foot { margin-top: auto; color: #8ea39a; font-size: 12px; }
.side-subject { margin-bottom: 6px; }
.side-sub, .side-task {
  display: block;
  width: 100%;
  text-align: left;
  border: 0;
  background: transparent;
  color: #d7e4dc;
  padding: 8px 10px;
  border-radius: 8px;
}
.side-sub { font-weight: 650; }
.side-sub.active, .side-task.active, .side-sub:hover, .side-task:hover { background: #24463d; }
.side-kids { padding: 4px 0 8px 10px; border-left: 2px solid #2c5348; margin: 0 8px 8px 14px; }
.side-mod { margin: 6px 0 10px; }
.side-mod-title { font-size: 12px; color: #9bb0a8; padding: 2px 10px 6px; }
.opt.picked { border-color: var(--pine); background: #e8f4ef; }
.task-link {
  display: flex;
  width: 100%;
  justify-content: space-between;
  align-items: center;
  gap: 8px;
  border: 0;
  background: #faf6ec;
  border-radius: 10px;
  padding: 8px 10px;
  margin: 6px 0;
  text-align: left;
}
.task-link:hover { background: #f3ead3; }
.diagnose h2 { margin-top: 0; }
.point { border-top: 1px dashed var(--line); padding-top: 10px; margin-top: 10px; }
.point h3 { margin: 0 0 6px; font-size: 18px; }
.listen-in, .speak-in { min-height: 72px; margin-top: 8px; }

.controls {
  position: sticky;
  top: 0;
  z-index: 4;
  background: #f3eee4f2;
  padding: 10px 0 12px;
  border-bottom: 1px solid var(--line);
  margin-bottom: 12px;
  backdrop-filter: blur(8px);
}
.control-row { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; margin-top: 8px; }
.control-row:first-child { margin-top: 0; }
.controls select, .controls input[type="search"] {
  width: auto;
  min-width: 140px;
}
.chk { display: flex; align-items: center; gap: 6px; color: var(--muted); font-size: 13px; }
.chk input { width: auto; }

.qcard {
  background: var(--sheet);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 16px 18px;
  margin: 14px 0;
}
.qcard h3 { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; margin: 0 0 10px; }
.qnumber { font-weight: 700; }
.tag { font-size: 12px; padding: 2px 8px; border-radius: 999px; background: #edf2f7; }
.tag.level { background: #e8f5ef; color: #1d6852; }
.tag.discuss { background: #f3e6c4; color: #7a5a10; }
.tag.wrong-reason { background: #f4ddd8; color: #8a3226; }
.reason-box { display: flex; align-items: center; gap: 6px; font-size: 13px; color: var(--muted); }
.reason-box[hidden] { display: none; }
.reason-box select { width: auto; min-width: 110px; padding: 5px 8px; }
.qcard .prompt { margin: 8px 0 12px; }
.qcard svg { display: block; max-width: 100%; height: auto; margin: 12px auto; }
.answer { border-top: 1px dashed var(--line); padding-top: 8px; }
.answer summary { color: var(--pine); cursor: pointer; }
.answer-body { background: #f2f8f6; padding: 8px 12px; margin-top: 8px; border-radius: 8px; }
.q-actions { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 12px; }
.mark {
  border: 1px solid var(--line);
  background: #fff;
  border-radius: 999px;
  padding: 5px 12px;
}
.mark.on-right { background: #dceee4; border-color: #1d6b4a; color: #1d5a3e; }
.mark.on-wrong { background: #f4ddd8; border-color: #a33b2b; color: #8a3226; }
.mark.on-discuss { background: #f3e6c4; border-color: #b0892a; color: #7a5a10; }
.mark:disabled { opacity: .7; cursor: default; }

.stage { padding: 28px 36px 48px; max-width: 1180px; }
.eyebrow { font-size: 12px; letter-spacing: .16em; color: var(--muted); margin: 0 0 6px; }
h1, h2, h3 { font-family: var(--serif); font-weight: 650; }
h1 { font-size: clamp(26px, 4vw, 36px); margin: 0; }
h2 { font-size: 22px; margin: 0 0 10px; }
.sub { color: var(--muted); margin: 8px 0 0; }

.row { display: flex; gap: 10px; flex-wrap: wrap; align-items: center; }
.btn, .btn-ghost, .btn-bad {
  border: 1px solid var(--line);
  background: var(--sheet);
  border-radius: 10px;
  padding: 8px 14px;
}
.btn { background: var(--pine); color: #fff; border-color: var(--pine); }
.btn-bad { color: var(--bad); border-color: #e3b8b2; }
.pills { display: flex; flex-wrap: wrap; gap: 8px; }
.pill {
  border: 1px solid var(--line);
  background: var(--sheet);
  border-radius: 999px;
  padding: 4px 10px;
  font-size: 13px;
}

.grid-3, .grid-2 { display: grid; gap: 14px; }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-2 { grid-template-columns: 1fr 1fr; }
.card {
  background: var(--sheet);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 16px 18px;
  box-shadow: 0 10px 28px rgba(28,42,43,.06);
}
.card.tap { cursor: pointer; }
.card.tap:hover { border-color: #c4b59a; }

.tree-branch { margin-top: 8px; }
.tree-node {
  border-left: 2px solid #c9ddd4;
  margin-left: 10px;
  padding: 4px 0 4px 12px;
}
.task {
  display: flex;
  justify-content: space-between;
  gap: 10px;
  align-items: center;
  padding: 8px 10px;
  border-radius: 10px;
  background: #faf6ec;
  margin: 6px 0;
}
.task:hover { background: #f3ead3; }
.st { font-size: 12px; padding: 2px 8px; border-radius: 999px; background: #efe7d6; }
.st.passed { background: #dceee4; color: #1d5a3e; }
.st.failed { background: #f4ddd8; color: #8a3226; }
.st.needs_review { background: #f3e6c4; color: #7a5a10; }
.st.in_progress { background: #d7ebe4; color: #1f5a4e; }

.timer { font-variant-numeric: tabular-nums; font-size: 22px; color: var(--pine); }
.quiz-word { font-family: var(--serif); font-size: 40px; margin: 8px 0; }
.options { display: grid; gap: 8px; margin: 12px 0; }
.opt {
  text-align: left;
  border: 1px solid var(--line);
  background: #fff;
  border-radius: 12px;
  padding: 10px 12px;
}
.opt.correct { border-color: var(--good); background: #e8f6ee; }
.opt.wrong { border-color: var(--bad); background: #fbecea; }
.feedback { background: #f6f1e6; border-radius: 12px; padding: 12px; margin-top: 12px; }
.passage { background: #faf6ec; border-left: 3px solid var(--gold); padding: 12px 14px; white-space: pre-wrap; border-radius: 0 12px 12px 0; }
.knowledge-html h2, .knowledge-html h3, .knowledge-html h4 { font-family: var(--serif); }
.knowledge-html table { border-collapse: collapse; width: 100%; margin: 14px 0; font-size: 14px; }
.knowledge-html th, .knowledge-html td { border: 1px solid var(--line); padding: 8px 10px; text-align: left; }
.knowledge-html th { background: #edf6f4; }
.knowledge-html svg { display: block; max-width: 100%; height: auto; margin: 12px auto; }
.knowledge-html ul { padding-left: 1.2em; }
.err { color: var(--bad); font-size: 13px; }
.bar { height: 8px; background: #e8e0d2; border-radius: 99px; overflow: hidden; }
.bar > i { display: block; height: 100%; background: var(--pine); }

@media (max-width: 900px) {
  .shell { grid-template-columns: 1fr; }
  .grid-3, .grid-2 { grid-template-columns: 1fr; }
  .stage { padding: 18px 16px 36px; }
}