:root {
  --bg: #f4f6fb;
  --card: #ffffff;
  --border: #e3e8f2;
  --text: #1e2433;
  --muted: #6b7688;
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --primary-soft: #eef4ff;
  --green: #16a34a;
  --green-soft: #eafaf0;
  --red: #dc2626;
  --red-soft: #fdeeee;
  --amber: #d97706;
  --amber-soft: #fff7e8;
  --radius: 12px;
  --shadow: 0 1px 2px rgba(16, 24, 40, .04), 0 8px 24px -12px rgba(16, 24, 40, .18);
}

* { box-sizing: border-box; }

html, body { margin: 0; padding: 0; }

body {
  background: var(--bg);
  color: var(--text);
  font-family: "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", system-ui, -apple-system,
    "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  font-size: 15px;
  line-height: 1.65;
}

a { color: var(--primary); text-decoration: none; }
a:hover { text-decoration: underline; }

.wrap { width: min(1080px, 100% - 32px); margin: 0 auto; }
.wrap-narrow { width: min(720px, 100% - 32px); margin: 0 auto; }

/* ---------------- 顶栏 ---------------- */
.topbar {
  background: #fff;
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 30;
}
.topbar .wrap { display: flex; align-items: center; justify-content: space-between; height: 58px; gap: 16px; }
.brand { display: flex; align-items: center; gap: 9px; font-weight: 700; font-size: 16px; color: var(--text); }
.brand:hover { text-decoration: none; }
.brand .logo {
  display: inline-grid; place-items: center;
  width: 28px; height: 28px; border-radius: 8px;
  background: linear-gradient(135deg, #2563eb, #7c3aed);
  color: #fff; font-size: 13px; font-weight: 800; letter-spacing: -.5px;
}
.topbar nav { display: flex; align-items: center; gap: 6px; flex-wrap: wrap; }
.topbar nav a, .topbar nav button {
  color: var(--muted); font-size: 14px; padding: 6px 10px; border-radius: 8px;
  border: 0; background: none; cursor: pointer; font-family: inherit;
}
.topbar nav a:hover, .topbar nav button:hover { background: var(--primary-soft); color: var(--primary); text-decoration: none; }
.topbar nav a.active { color: var(--primary); background: var(--primary-soft); }
.inline { display: inline; }

main { padding: 26px 0 60px; }

/* ---------------- 通用块 ---------------- */
.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 22px 24px;
}
.card + .card { margin-top: 18px; }
.card h2 { margin: 0 0 14px; font-size: 17px; }
.card h3 { margin: 0 0 10px; font-size: 15px; }
.muted { color: var(--muted); }
.small { font-size: 13px; }
.center { text-align: center; }
.mt-0 { margin-top: 0; }
.mb-0 { margin-bottom: 0; }
.row { display: flex; gap: 10px; align-items: center; flex-wrap: wrap; }
.spread { display: flex; align-items: center; justify-content: space-between; gap: 14px; flex-wrap: wrap; }
.grow { flex: 1 1 auto; }

.page-head { margin-bottom: 18px; }
.page-head h1 { margin: 0 0 4px; font-size: 24px; letter-spacing: -.3px; }
.page-head p { margin: 0; color: var(--muted); font-size: 14px; }

/* ---------------- 表单控件 ---------------- */
label.field { display: block; margin-bottom: 14px; }
label.field > span.lbl { display: block; font-size: 13px; font-weight: 600; color: #3c4658; margin-bottom: 6px; }
label.field .hint { font-size: 12px; color: var(--muted); font-weight: 400; margin-left: 6px; }

input[type="text"], input[type="password"], input[type="number"], select, textarea {
  width: 100%;
  padding: 9px 12px;
  border: 1px solid var(--border);
  border-radius: 9px;
  font-family: inherit;
  font-size: 14px;
  color: var(--text);
  background: #fff;
  transition: border-color .15s, box-shadow .15s;
}
input:focus, select:focus, textarea:focus {
  outline: none; border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, .14);
}
textarea { resize: vertical; min-height: 76px; line-height: 1.7; }
textarea.mono, input.mono { font-family: "Cascadia Mono", Consolas, "Courier New", monospace; font-size: 13px; }

.grid-2 { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 0 16px; }
.grid-3 { display: grid; grid-template-columns: repeat(auto-fit, minmax(170px, 1fr)); gap: 0 16px; }

.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 6px;
  padding: 9px 18px; border-radius: 9px; border: 1px solid var(--border);
  background: #fff; color: var(--text); font-size: 14px; font-weight: 600;
  font-family: inherit; cursor: pointer; text-decoration: none;
  transition: background .15s, border-color .15s, transform .06s;
}
.btn:hover { background: #f7f9fc; text-decoration: none; }
.btn:active { transform: translateY(1px); }
.btn-primary { background: var(--primary); border-color: var(--primary); color: #fff; }
.btn-primary:hover { background: var(--primary-dark); border-color: var(--primary-dark); }
.btn-danger { color: var(--red); border-color: #f3cccc; background: #fff; }
.btn-danger:hover { background: var(--red-soft); }
.btn-lg { padding: 12px 28px; font-size: 15px; border-radius: 10px; }
.btn-sm { padding: 5px 11px; font-size: 13px; border-radius: 7px; }
.btn-ghost { border-color: transparent; background: transparent; color: var(--muted); }
.btn-ghost:hover { background: #f2f5fa; }

.chips { display: flex; gap: 8px; flex-wrap: wrap; }
.chip {
  padding: 5px 12px; border-radius: 999px; border: 1px solid var(--border);
  background: #fff; font-size: 13px; cursor: pointer; color: var(--muted);
  font-family: inherit;
}
.chip:hover { border-color: #c8d4ea; color: var(--text); }
.chip.on { background: var(--primary-soft); border-color: #bcd2fb; color: var(--primary); font-weight: 600; }

/* ---------------- 提示条 ---------------- */
.alert { padding: 11px 14px; border-radius: 10px; font-size: 14px; margin-bottom: 16px; border: 1px solid transparent; }
.alert-info { background: var(--primary-soft); border-color: #cfe0ff; color: #1e40af; }
.alert-ok { background: var(--green-soft); border-color: #c3ecd3; color: #15803d; }
.alert-err { background: var(--red-soft); border-color: #f4cfcf; color: #b91c1c; }
.alert-warn { background: var(--amber-soft); border-color: #f5e0b8; color: #b45309; }

/* ---------------- 首页 ---------------- */
.hero { text-align: center; padding: 14px 0 8px; }
.hero h1 { font-size: 27px; margin: 0 0 8px; letter-spacing: -.5px; }
.hero p { color: var(--muted); margin: 0 auto; max-width: 560px; }
.stat-row { display: grid; grid-template-columns: repeat(auto-fit, minmax(130px, 1fr)); gap: 12px; margin: 22px 0 4px; }
.stat {
  background: #fff; border: 1px solid var(--border); border-radius: var(--radius);
  padding: 14px 16px; text-align: center;
}
.stat .num { font-size: 22px; font-weight: 700; letter-spacing: -.5px; }
.stat .k { font-size: 12px; color: var(--muted); margin-top: 2px; }

/* ---------------- 答题卡 ---------------- */
.exam-bar {
  position: sticky; top: 58px; z-index: 20;
  background: rgba(255, 255, 255, .92);
  backdrop-filter: blur(8px);
  border: 1px solid var(--border); border-radius: var(--radius);
  padding: 10px 16px; margin-bottom: 18px;
  display: flex; align-items: center; justify-content: space-between; gap: 14px; flex-wrap: wrap;
  box-shadow: var(--shadow);
}
.progress { flex: 1 1 200px; height: 8px; border-radius: 999px; background: #e8edf6; overflow: hidden; min-width: 140px; }
.progress > i { display: block; height: 100%; width: 0; background: linear-gradient(90deg, #2563eb, #7c3aed); transition: width .25s; }
.exam-meta { font-size: 13px; color: var(--muted); white-space: nowrap; }

.section-head {
  display: flex; align-items: baseline; gap: 10px;
  margin: 26px 0 12px; padding-left: 11px; border-left: 4px solid var(--primary);
}
.section-head h2 { margin: 0; font-size: 17px; }
.section-head span { font-size: 13px; color: var(--muted); }

.q {
  background: #fff; border: 1px solid var(--border); border-radius: var(--radius);
  padding: 18px 20px; margin-bottom: 14px; box-shadow: var(--shadow);
}
.q.answered { border-color: #cfe0ff; }
.q-head { display: flex; gap: 10px; align-items: flex-start; margin-bottom: 10px; }
.q-no {
  flex: 0 0 auto; min-width: 30px; height: 26px; padding: 0 8px;
  display: inline-grid; place-items: center; border-radius: 8px;
  background: var(--primary-soft); color: var(--primary); font-weight: 700; font-size: 13px;
}
.q.answered .q-no { background: var(--primary); color: #fff; }
.q-stem { flex: 1 1 auto; font-size: 15px; line-height: 1.8; }
.q-tags { margin-top: 6px; }
.tag {
  display: inline-block; font-size: 12px; color: var(--muted);
  background: #f3f5fa; border-radius: 6px; padding: 1px 8px; margin-right: 6px;
}
pre.code {
  background: #0f172a; color: #e2e8f0; border-radius: 10px;
  padding: 14px 16px; overflow-x: auto; font-size: 13px; line-height: 1.65;
  font-family: "Cascadia Mono", Consolas, "Courier New", monospace; margin: 0 0 14px;
}
pre.code code { font-family: inherit; }

.opts { display: grid; gap: 8px; margin-top: 12px; }
.opts.judge { grid-template-columns: repeat(auto-fit, minmax(140px, 1fr)); max-width: 420px; }
.opt {
  display: flex; align-items: flex-start; gap: 10px;
  border: 1px solid var(--border); border-radius: 10px;
  padding: 9px 13px; cursor: pointer; background: #fff;
  transition: border-color .12s, background .12s;
}
.opt:hover { border-color: #c3d3f0; background: #fafcff; }
.opt input { margin: 0; position: absolute; opacity: 0; pointer-events: none; }
.opt .opt-key {
  flex: 0 0 auto; width: 24px; height: 24px; border-radius: 50%;
  display: inline-grid; place-items: center; font-size: 13px; font-weight: 700;
  background: #f1f4fa; color: var(--muted);
}
.opt .opt-text { flex: 1 1 auto; }
.opt:has(input:checked) { border-color: var(--primary); background: var(--primary-soft); }
.opt:has(input:checked) .opt-key { background: var(--primary); color: #fff; }
.opt:has(input:focus-visible) { box-shadow: 0 0 0 3px rgba(37, 99, 235, .18); }

/* ---------------- 结果页 ---------------- */
.score-hero {
  background: linear-gradient(135deg, #1e3a8a, #4c1d95);
  color: #fff; border-radius: 16px; padding: 28px 30px; text-align: center;
  box-shadow: 0 18px 40px -22px rgba(30, 58, 138, .8);
}
.score-hero .big { font-size: 52px; font-weight: 800; line-height: 1.05; letter-spacing: -2px; }
.score-hero .big small { font-size: 20px; font-weight: 600; opacity: .7; letter-spacing: 0; }
.score-hero .sub { opacity: .85; margin-top: 6px; font-size: 14px; }
.score-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(120px, 1fr)); gap: 12px; margin-top: 22px; }
.score-grid .item { background: rgba(255, 255, 255, .12); border-radius: 12px; padding: 11px 12px; }
.score-grid .item b { display: block; font-size: 19px; }
.score-grid .item span { font-size: 12px; opacity: .8; }

.bar { height: 8px; border-radius: 999px; background: #e8edf6; overflow: hidden; }
.bar > i { display: block; height: 100%; background: var(--green); }
.bar.low > i { background: var(--amber); }
.bar.bad > i { background: var(--red); }

.review { border: 1px solid var(--border); border-radius: var(--radius); background: #fff; padding: 18px 20px; margin-bottom: 14px; }
.review.wrong { border-left: 4px solid var(--red); }
.review.right { border-left: 4px solid var(--green); }
.ans-line { display: flex; gap: 18px; flex-wrap: wrap; margin: 10px 0 0; font-size: 14px; }
.ans-line .you.bad { color: var(--red); font-weight: 600; }
.ans-line .you.good { color: var(--green); font-weight: 600; }
.ans-line .right { color: var(--green); font-weight: 600; }
.analysis {
  margin-top: 12px; padding: 11px 14px; border-radius: 10px;
  background: #f7f9fc; border: 1px dashed #d7deeb; font-size: 14px; color: #3c4658;
}
.analysis b { color: var(--text); }
.verdict { font-size: 13px; font-weight: 700; padding: 2px 10px; border-radius: 999px; }
.verdict.ok { color: var(--green); background: var(--green-soft); }
.verdict.no { color: var(--red); background: var(--red-soft); }

/* ---------------- 表格 ---------------- */
.table-wrap { overflow-x: auto; }
table.tbl { width: 100%; border-collapse: collapse; font-size: 14px; }
table.tbl th, table.tbl td { padding: 10px 12px; border-bottom: 1px solid var(--border); text-align: left; vertical-align: top; }
table.tbl th { font-size: 12px; color: var(--muted); font-weight: 600; background: #fafbfe; white-space: nowrap; }
table.tbl tr:hover td { background: #fafcff; }
table.tbl td.stem-cell { max-width: 460px; }
table.tbl td.stem-cell .snip { display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; }
table.tbl td.actions { white-space: nowrap; }
.badge { display: inline-block; font-size: 12px; padding: 1px 9px; border-radius: 999px; background: #f1f4fa; color: var(--muted); }
.badge.on { background: var(--green-soft); color: var(--green); }
.badge.off { background: #f2f3f6; color: #98a1b3; }
.badge.type-single { background: var(--primary-soft); color: var(--primary); }
.badge.type-judge { background: #f3ecff; color: #7c3aed; }
.diff { color: var(--amber); letter-spacing: 1px; font-size: 12px; }

.pager { display: flex; gap: 6px; align-items: center; justify-content: center; margin-top: 16px; flex-wrap: wrap; }
.pager a, .pager span {
  min-width: 32px; padding: 5px 10px; border-radius: 8px; border: 1px solid var(--border);
  background: #fff; font-size: 13px; text-align: center; color: var(--text);
}
.pager a:hover { border-color: var(--primary); color: var(--primary); text-decoration: none; }
.pager span.cur { background: var(--primary); border-color: var(--primary); color: #fff; font-weight: 600; }
.pager span.dis { color: #c3cad8; }

details.panel { border: 1px solid var(--border); border-radius: var(--radius); background: #fff; padding: 0; margin-top: 18px; overflow: hidden; }
details.panel > summary { padding: 13px 20px; cursor: pointer; font-weight: 600; font-size: 14px; list-style: none; }
details.panel > summary::-webkit-details-marker { display: none; }
details.panel > summary::before { content: "▸ "; color: var(--muted); }
details.panel[open] > summary::before { content: "▾ "; }
details.panel > summary:hover { background: #fafbfe; }
details.panel .panel-body { padding: 4px 20px 20px; }

footer.site { padding: 26px 0 40px; text-align: center; color: #9aa3b4; font-size: 12px; }

.login-card { margin-top: 6vh; }
.empty { text-align: center; color: var(--muted); padding: 40px 0; }

@media (max-width: 640px) {
  .q { padding: 15px 15px; }
  .card { padding: 18px 16px; }
  .score-hero { padding: 22px 18px; }
  .score-hero .big { font-size: 42px; }
  .topbar .wrap { height: auto; padding: 10px 0; }
}

/* ========================================================================== */
/* 富文本（Markdown / LaTeX / 图片）                                          */
/* ========================================================================== */
.rich { line-height: 1.8; word-wrap: break-word; overflow-wrap: anywhere; }
.rich > *:first-child { margin-top: 0; }
.rich > *:last-child { margin-bottom: 0; }
.rich p { margin: 0 0 8px; }
.rich ul, .rich ol { margin: 6px 0 8px; padding-left: 24px; }
.rich li { margin: 2px 0; }
.rich h1, .rich h2, .rich h3, .rich h4 { margin: 14px 0 8px; font-size: 15px; line-height: 1.5; }
.rich blockquote {
  margin: 8px 0; padding: 6px 12px; border-left: 3px solid var(--border);
  background: #fafbfe; color: var(--muted);
}
.rich code {
  background: #f2f4f9; border-radius: 5px; padding: 1px 5px;
  font-family: "Cascadia Mono", Consolas, "Courier New", monospace; font-size: 13px;
}
.rich pre {
  background: #0f172a; color: #e2e8f0; border-radius: 10px; padding: 12px 14px;
  overflow-x: auto; font-size: 13px; margin: 8px 0;
}
.rich pre code { background: none; color: inherit; padding: 0; font-size: 13px; }
.rich table { border-collapse: collapse; margin: 8px 0; font-size: 13px; }
.rich th, .rich td { border: 1px solid var(--border); padding: 5px 10px; }
.rich th { background: #fafbfe; }
.rich a { word-break: break-all; }
.rich hr { border: 0; border-top: 1px solid var(--border); margin: 12px 0; }

.md-img {
  display: block; max-width: 100%; height: auto; margin: 10px 0;
  border: 1px solid var(--border); border-radius: 10px; background: #fff;
}
.opt-text .md-img, .snip .md-img { display: inline-block; max-height: 120px; margin: 4px 0; }

.md-math { display: inline-block; max-width: 100%; overflow-x: auto; vertical-align: middle; }
.md-math math { font-size: 1.06em; }
.md-math-block {
  display: block; text-align: center; margin: 10px 0; padding: 6px 4px;
  background: #fafbfe; border-radius: 8px; overflow-x: auto;
}
.md-math-block math { font-size: 1.12em; }
.math-fallback {
  background: var(--amber-soft) !important; color: var(--amber);
  border-radius: 5px; padding: 1px 6px;
}

/* ========================================================================== */
/* 大题材料                                                                    */
/* ========================================================================== */
.material {
  background: linear-gradient(180deg, #f7faff, #ffffff);
  border: 1px solid #d9e4f7; border-left: 4px solid var(--primary);
  border-radius: var(--radius); padding: 16px 20px; margin: 18px 0 12px;
  box-shadow: var(--shadow);
}
.material-head { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; margin-bottom: 8px; }
.material-head b { font-size: 15.5px; }
.material-badge {
  font-size: 12px; font-weight: 700; color: #fff; background: var(--primary);
  border-radius: 6px; padding: 1px 8px;
}
.material-desc { font-size: 14px; color: #3c4658; margin-bottom: 10px; }
.material .code, .material pre.code { margin-bottom: 0; }
.q.in-material, .review.in-material { margin-left: 14px; border-left: 3px solid #e2e9f7; }

/* ========================================================================== */
/* 首页：出题方式选择                                                          */
/* ========================================================================== */
.mode-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 12px; margin-bottom: 18px; }
.mode-card {
  text-align: left; background: #fff; border: 2px solid var(--border); border-radius: var(--radius);
  padding: 14px 16px; cursor: pointer; font-family: inherit; color: var(--text); line-height: 1.6;
  transition: border-color .15s, background .15s;
}
.mode-card:hover:not(:disabled) { border-color: #c3d3f0; background: #fafcff; }
.mode-card.on { border-color: var(--primary); background: var(--primary-soft); }
.mode-card:disabled { opacity: .5; cursor: not-allowed; }
.mode-card b { display: block; font-size: 15px; margin-bottom: 4px; }
.mode-card span { font-size: 13px; color: var(--muted); }

.paper-list { display: grid; gap: 10px; }
.paper-card {
  display: flex; gap: 12px; align-items: flex-start;
  border: 1px solid var(--border); border-radius: var(--radius); padding: 13px 15px;
  cursor: pointer; background: #fff;
}
.paper-card:hover { border-color: #c3d3f0; background: #fafcff; }
.paper-card:has(input:checked) { border-color: var(--primary); background: var(--primary-soft); }
.paper-card input { margin-top: 4px; width: auto; flex: 0 0 auto; }
.paper-body { flex: 1 1 auto; }
.paper-body .spread { gap: 8px; }
.paper-body p { margin: 6px 0; }
.paper-body .chips { margin-top: 8px; }

/* ========================================================================== */
/* 结果页：选项对错标记                                                        */
/* ========================================================================== */
.opt-right { border-color: var(--green) !important; background: var(--green-soft) !important; cursor: default; }
.opt-wrong { border-color: var(--red) !important; background: var(--red-soft) !important; cursor: default; }
.mark-right { color: var(--green); font-size: 12px; margin-left: 4px; }
.mark-wrong { color: var(--red); font-size: 12px; margin-left: 4px; }

/* ========================================================================== */
/* 管理端：选择列表与预览                                                      */
/* ========================================================================== */
.pick-list { display: grid; gap: 6px; max-height: 420px; overflow-y: auto; padding-right: 4px; }
.pick {
  display: flex; gap: 10px; align-items: flex-start;
  border: 1px solid var(--border); border-radius: 9px; padding: 8px 12px; background: #fff;
  font-size: 14px; cursor: pointer;
}
.pick:hover { border-color: #c3d3f0; background: #fafcff; }
.pick:has(input:checked) { border-color: var(--primary); background: var(--primary-soft); }
.pick.used { background: #fbfcfe; }
.pick input { margin-top: 3px; width: auto; flex: 0 0 auto; }
.pick .badge { margin-left: 4px; }

.preview-box {
  margin-top: 12px; padding: 14px 16px; border: 1px dashed #d7deeb;
  border-radius: var(--radius); background: #fbfcfe; min-height: 60px;
}

/* ========================================================================== */
/* 组卷编辑器                                                                  */
/* ========================================================================== */
.compose-panel > summary { font-size: 14.5px; }
.nowrap { white-space: nowrap; }
.rich-inline p { display: inline; margin: 0; }

.paper-section {
  border: 1px solid var(--border); border-radius: var(--radius);
  padding: 12px 14px; margin: 14px 0; background: #fcfdff;
}
.paper-section-head {
  display: flex; align-items: baseline; gap: 10px;
  margin-bottom: 10px; padding-left: 9px; border-left: 4px solid var(--primary);
}
.paper-item {
  background: #fff; border: 1px solid var(--border); border-radius: 10px;
  padding: 10px 12px; margin-bottom: 8px;
}
.paper-item.is-group { border-left: 3px solid #7c3aed; }
.paper-item-head { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.paper-item-no {
  font-weight: 700; color: var(--muted); font-size: 12px;
  min-width: 22px; text-align: center;
}
.paper-item-title { flex: 1 1 auto; min-width: 180px; }
.paper-item-actions { display: flex; gap: 6px; flex-wrap: wrap; margin-top: 8px; }
.code-mini { max-height: 190px; font-size: 12px; padding: 10px 12px; margin: 4px 0 6px; }
.sub-list { margin: 8px 0 0; padding-left: 22px; font-size: 13.5px; }
.sub-list li { margin: 3px 0; }

.sub-head {
  display: flex; align-items: center; gap: 10px; flex-wrap: wrap;
  margin: 18px 0 10px; padding-top: 12px; border-top: 1px dashed var(--border);
}
.sub-head .btn { margin-left: auto; }
.sub-row {
  border: 1px solid var(--border); border-radius: 10px;
  padding: 12px 14px; margin-bottom: 10px; background: #fbfcfe;
}
.sub-row-head {
  display: flex; align-items: center; justify-content: space-between;
  gap: 10px; flex-wrap: wrap; margin-bottom: 8px;
}
.sub-row-head .row { gap: 12px; }
.sub-row textarea { min-height: 56px; }