:root {
  --ink: #17231c;
  --muted: #68736b;
  --paper: #fbfaf5;
  --line: #d9ddd4;
  --accent: #2f6849;
  --soft: #e9f0e8;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  font: 15px/1.75 "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
}
a { color: inherit; }
.mast {
  min-height: 58svh;
  padding: 34px clamp(22px, 6vw, 88px) 54px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  background: linear-gradient(120deg, #173f2d, #285e43 60%, #426d54);
  color: #f7f5eb;
}
.brand { font: 600 18px/1 "Avenir Next", system-ui; letter-spacing: .03em; }
.hero { max-width: 900px; padding: 80px 0 22px; }
.eyebrow { font-size: 12px; letter-spacing: .16em; opacity: .75; }
.hero h1 {
  font: 500 clamp(42px, 8vw, 86px)/1.08 "Songti SC", "STSong", serif;
  margin: 18px 0 24px;
  letter-spacing: -.03em;
}
.hero p { max-width: 590px; font-size: 17px; opacity: .82; margin: 0; }
main { max-width: 1120px; margin: auto; padding: 70px clamp(20px, 5vw, 58px) 100px; }
.intro {
  display: grid;
  grid-template-columns: minmax(180px, .7fr) minmax(0, 1.6fr);
  gap: 56px;
  padding-bottom: 48px;
  border-bottom: 1px solid var(--line);
}
h2 { font: 500 30px/1.25 "Songti SC", "STSong", serif; margin: 0; }
.intro p { margin: 0; color: var(--muted); max-width: 680px; }
.weakness {
  padding: 64px 0 56px;
  border-bottom: 1px solid var(--line);
}
.weakness-head {
  display: grid;
  grid-template-columns: minmax(220px, .8fr) minmax(0, 1.4fr);
  gap: 56px;
  align-items: end;
  margin-bottom: 30px;
}
.section-kicker {
  margin: 0 0 8px;
  color: var(--accent);
  font-size: 11px;
  letter-spacing: .14em;
}
.weakness-head > p { margin: 0; color: var(--muted); max-width: 600px; }
.weak-list { list-style: none; margin: 0; padding: 0; border-top: 1px solid var(--line); }
.weak-row { border-bottom: 1px solid var(--line); }
.weak-row.has-material { background: linear-gradient(90deg, var(--soft), transparent 72%); }
.weak-row a {
  display: grid;
  grid-template-columns: 54px minmax(0, 1fr) minmax(170px, .45fr);
  gap: 24px;
  align-items: center;
  min-height: 102px;
  padding: 18px 0;
  text-decoration: none;
}
.weak-rank { color: #8b948d; font: 500 13px/1 "Avenir Next", system-ui; }
.weak-copy { display: grid; gap: 5px; }
.weak-copy strong { font-size: 17px; font-weight: 550; }
.weak-copy small { color: var(--muted); font-size: 12px; }
.weak-evidence { position: relative; padding-bottom: 14px; color: var(--muted); font-size: 11px; }
.weak-evidence b { color: var(--ink); font: 500 24px/1 "Avenir Next", system-ui; }
.weak-evidence i {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 2px;
  background: linear-gradient(to right, var(--accent) calc(var(--strength) * 100%), var(--line) 0);
}
.weak-row a:hover .weak-copy strong { color: var(--accent); }
.item { scroll-margin-top: 20px; }
.tools { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; margin: 32px 0; }
.filter {
  border: 1px solid var(--line);
  background: transparent;
  color: var(--ink);
  border-radius: 999px;
  padding: 8px 15px;
  cursor: pointer;
}
.filter[aria-pressed="true"] { background: var(--ink); border-color: var(--ink); color: white; }
.lesson-filter { border-color: #7da48c; color: var(--accent); }
.paper { padding: 42px 0 10px; }
.paper-head { display: flex; align-items: baseline; justify-content: space-between; gap: 20px; margin-bottom: 8px; }
.paper-head h2 { font-size: 26px; }
.paper-head span { font-size: 12px; color: var(--muted); }
.item { border-top: 1px solid var(--line); }
.item.has-lesson {
  margin: 0 -16px;
  padding: 0 16px;
  border-top-color: #9bb7a4;
  background: linear-gradient(90deg, #e8f0e7 0, rgba(232, 240, 231, .42) 60%, transparent 100%);
  transition: background .18s ease;
}
.item.has-lesson:hover { background-color: #e3ece2; }
.item:last-child { border-bottom: 1px solid var(--line); }
.item summary, .direct-lesson {
  list-style: none;
  display: grid;
  grid-template-columns: 80px minmax(0, 1fr) auto;
  gap: 24px;
  align-items: start;
  padding: 25px 0;
  cursor: pointer;
}
.direct-lesson { color: inherit; text-decoration: none; }
.direct-lesson:hover .stem { color: var(--accent); }
.item summary::-webkit-details-marker { display: none; }
.number { font: 500 18px/1.5 "Avenir Next", system-ui; }
.stem { font-size: 16px; line-height: 1.7; }
.tag {
  font-size: 11px;
  color: var(--accent);
  background: var(--soft);
  border-radius: 999px;
  padding: 4px 10px;
  white-space: nowrap;
}
.tags { display: flex; justify-content: flex-end; gap: 7px; flex-wrap: wrap; }
.tag.material { color: white; background: var(--accent); }
.workbook-paper { scroll-margin-top: 16px; }
.workbook-topics { color: var(--muted); margin: 6px 0 15px; }
.workbook-focus { display: block; color: var(--muted); margin-top: 4px; font-size: 13px; }
.hero a { display: inline-block; margin-top: 8px; text-underline-offset: 4px; }
.item[open] summary { padding-bottom: 16px; }
.analysis { margin: 0 0 30px 104px; max-width: 760px; animation: reveal .18s ease-out; }
.analysis h3 { font-size: 12px; color: var(--muted); font-weight: 500; margin: 20px 0 4px; letter-spacing: .04em; }
.analysis p { margin: 0; }
.skills { color: var(--muted); }
.lesson {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  margin-top: 24px;
  padding: 12px 18px;
  background: var(--accent);
  color: white;
  text-decoration: none;
  border-radius: 4px;
  transition: transform .18s ease, background .18s ease;
}
.lesson:hover { transform: translateY(-2px); background: #24563b; }
.lesson::after { content: "→"; font-size: 18px; }
.pending { margin-top: 20px; color: var(--muted); font-size: 13px; }
.student-review { margin-top: 76px; padding-top: 58px; border-top: 1px solid var(--line); }
.student-review-head {
  display: grid;
  grid-template-columns: minmax(220px, .8fr) minmax(0, 1.4fr);
  gap: 56px;
  align-items: end;
  margin-bottom: 30px;
}
.student-review-head > p { margin: 0; color: var(--muted); max-width: 650px; }
.review-item { border-top: 1px solid var(--line); }
.review-item:last-child { border-bottom: 1px solid var(--line); }
.review-item summary {
  list-style: none;
  display: grid;
  grid-template-columns: minmax(210px, .62fr) minmax(0, 1.38fr) auto;
  gap: 24px;
  align-items: start;
  padding: 24px 0;
  cursor: pointer;
}
.review-item summary::-webkit-details-marker { display: none; }
.review-source { display: grid; gap: 5px; padding-top: 2px; }
.review-source b { font-size: 13px; line-height: 1.45; font-weight: 550; }
.review-source em {
  color: var(--accent);
  font: 500 18px/1.25 "Avenir Next", system-ui;
  font-style: normal;
}
.review-tag { color: #7a5934; background: #f2e9dc; }
.review-body { margin: 0 0 32px calc(31% + 24px); max-width: 760px; }
.review-body > p { color: var(--muted); margin: 12px 0; }
.review-body strong { display: block; color: var(--ink); font-size: 12px; font-weight: 550; }
.review-form { display: grid; gap: 12px; margin-top: 20px; }
.review-form label { display: grid; gap: 7px; font-size: 12px; color: var(--muted); }
.review-form input {
  width: 100%;
  border: 1px solid #b8c3b9;
  border-radius: 4px;
  background: white;
  color: var(--ink);
  padding: 11px 12px;
  font: inherit;
}
.review-form div { display: flex; gap: 8px; flex-wrap: wrap; }
.review-form button { border: 0; border-radius: 4px; padding: 9px 13px; cursor: pointer; }
.confirm-review { background: var(--accent); color: white; }
.unknown-review { background: var(--soft); color: var(--ink); }
.review-status { min-height: 24px; color: var(--accent) !important; font-size: 12px; }
.foot { max-width: 1120px; margin: auto; padding: 26px clamp(20px, 5vw, 58px) 50px; border-top: 1px solid var(--line); font-size: 12px; color: var(--muted); }
[hidden] { display: none !important; }
@keyframes reveal { from { opacity: 0; transform: translateY(-4px); } }
@media (max-width: 700px) {
  .mast { min-height: 50svh; }
  .hero { padding: 56px 0 36px; }
  .hero p { font-size: 15px; }
  .intro { display: block; }
  .intro h2 { margin-bottom: 16px; }
  .weakness { padding: 48px 0 40px; }
  .weakness-head { display: block; margin-bottom: 24px; }
  .weakness-head h2 { margin-bottom: 14px; }
  .weak-row a { grid-template-columns: 38px 1fr; gap: 12px; min-height: 0; padding: 19px 0; }
  .weak-evidence { grid-column: 2; }
  .paper { padding-top: 32px; }
  .item summary, .direct-lesson { grid-template-columns: 56px 1fr; gap: 12px; }
  .tags { grid-column: 2; justify-self: start; justify-content: flex-start; }
  .analysis { margin-left: 68px; }
  .stem { font-size: 15px; }
  .student-review { margin-top: 56px; padding-top: 42px; }
  .student-review-head { display: block; margin-bottom: 24px; }
  .student-review-head h2 { margin-bottom: 14px; }
  .review-item summary { grid-template-columns: 1fr auto; gap: 12px 16px; }
  .review-source { grid-column: 1; }
  .review-item .stem { grid-column: 1 / -1; }
  .review-item .tag { grid-column: 2; grid-row: 1; justify-self: end; }
  .review-body { margin-left: 0; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .analysis, .lesson, .item.has-lesson { animation: none; transition: none; }
}