:root {
  --bg: #f4f6fb;
  --surface: #ffffff;
  --surface-2: #f8fafc;
  --border: #e4e9f2;
  --border-strong: #cfd8e8;
  --text: #1e293b;
  --text-2: #475569;
  --muted: #8494ad;
  --primary: #2563eb;
  --primary-soft: #eaf1ff;
  --primary-dark: #1d4ed8;
  --accent: #7c3aed;
  --success: #16a34a;
  --success-soft: #e8f7ee;
  --danger: #dc2626;
  --danger-soft: #fdecec;
  --warn: #d97706;
  --warn-soft: #fef4e6;
  --radius: 12px;
  --radius-sm: 8px;
  --shadow: 0 1px 2px rgba(15, 23, 42, .05), 0 6px 20px rgba(15, 23, 42, .05);
  --mono: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", sans-serif;
  font-size: 15px;
  line-height: 1.7;
  -webkit-text-size-adjust: 100%;
}

button { font: inherit; cursor: pointer; }
input, textarea, select { font: inherit; color: inherit; }

/* ---------- header ---------- */
.app-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(255, 255, 255, .92);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
}
.header-inner {
  max-width: 1120px;
  margin: 0 auto;
  padding: 10px 16px;
  display: flex;
  align-items: center;
  gap: 16px;
}
.brand {
  display: flex;
  align-items: center;
  gap: 9px;
  font-weight: 700;
  font-size: 16px;
  letter-spacing: .2px;
  white-space: nowrap;
}
.brand-badge {
  width: 30px; height: 30px;
  border-radius: 8px;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  color: #fff;
  display: grid; place-items: center;
  font-size: 13px; font-weight: 800;
}
.brand small { color: var(--muted); font-weight: 500; font-size: 12px; }
.main-nav { display: flex; gap: 4px; margin-left: auto; flex-wrap: wrap; }
.main-nav button {
  border: 0;
  background: transparent;
  color: var(--text-2);
  padding: 7px 13px;
  border-radius: 999px;
  font-size: 14px;
  transition: .15s;
}
.main-nav button:hover { background: var(--surface-2); color: var(--primary); }
.main-nav button.active { background: var(--primary); color: #fff; }
.nav-toggle { display: none; margin-left: auto; border: 1px solid var(--border-strong); background: #fff; border-radius: 8px; padding: 6px 10px; }

/* ---------- layout ---------- */
.container { max-width: 1120px; margin: 0 auto; padding: 20px 16px 64px; }
.view { animation: fade .25s ease; }
@keyframes fade { from { opacity: 0; transform: translateY(4px); } to { opacity: 1; transform: none; } }

.page-title { font-size: 22px; font-weight: 700; margin: 0 0 4px; }
.page-desc { color: var(--text-2); font-size: 14px; margin: 0 0 18px; }
.section-title { font-size: 17px; font-weight: 700; margin: 26px 0 12px; display: flex; align-items: center; gap: 8px; }
.section-title::before { content: ""; width: 4px; height: 16px; border-radius: 2px; background: var(--primary); }

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px;
  box-shadow: var(--shadow);
}
.card + .card { margin-top: 14px; }

.grid { display: grid; gap: 14px; }
.grid-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }

/* ---------- buttons ---------- */
.btn {
  border: 1px solid var(--border-strong);
  background: #fff;
  color: var(--text);
  border-radius: var(--radius-sm);
  padding: 9px 16px;
  transition: .15s;
  font-size: 14px;
}
.btn:hover { border-color: var(--primary); color: var(--primary); }
.btn-primary { background: var(--primary); border-color: var(--primary); color: #fff; }
.btn-primary:hover { background: var(--primary-dark); border-color: var(--primary-dark); color: #fff; }
.btn-ghost { background: transparent; border-color: transparent; color: var(--text-2); }
.btn-ghost:hover { background: var(--surface-2); }
.btn-sm { padding: 5px 11px; font-size: 13px; }
.btn-block { display: block; width: 100%; }
.btn:disabled { opacity: .5; cursor: not-allowed; }

/* ---------- chips / tags ---------- */
.chip {
  display: inline-flex; align-items: center; gap: 5px;
  background: var(--surface-2);
  border: 1px solid var(--border);
  color: var(--text-2);
  border-radius: 999px;
  padding: 2px 10px;
  font-size: 12px;
  line-height: 1.8;
}
.chip-primary { background: var(--primary-soft); border-color: #cdddff; color: var(--primary-dark); }
.chip-success { background: var(--success-soft); border-color: #c6e9d3; color: #15803d; }
.chip-danger { background: var(--danger-soft); border-color: #f7cccc; color: #b91c1c; }
.chip-warn { background: var(--warn-soft); border-color: #f7e0b8; color: #b45309; }

/* ---------- filters ---------- */
.filter-bar {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 14px 16px;
  box-shadow: var(--shadow);
}
.filter-row { display: flex; flex-wrap: wrap; gap: 10px 18px; }
.filter-group { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.filter-group > label { font-size: 13px; color: var(--muted); min-width: 44px; }
.filter-opts { display: flex; gap: 6px; flex-wrap: wrap; }
.filter-opts button {
  border: 1px solid var(--border-strong);
  background: #fff;
  border-radius: 999px;
  padding: 4px 12px;
  font-size: 13px;
  color: var(--text-2);
  transition: .15s;
}
.filter-opts button:hover { border-color: var(--primary); color: var(--primary); }
.filter-opts button.active { background: var(--primary); border-color: var(--primary); color: #fff; }
select.control, input.control, textarea.control {
  border: 1px solid var(--border-strong);
  background: #fff;
  border-radius: var(--radius-sm);
  padding: 7px 10px;
  font-size: 14px;
  outline: none;
}
select.control:focus, input.control:focus, textarea.control:focus { border-color: var(--primary); }

/* ---------- quiz ---------- */
.quiz-head {
  display: flex; align-items: center; gap: 12px; flex-wrap: wrap;
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 12px 16px; box-shadow: var(--shadow);
  position: sticky; top: 56px; z-index: 20;
}
.quiz-progress { flex: 1; min-width: 160px; }
.quiz-progress .bar { height: 7px; background: var(--surface-2); border-radius: 999px; overflow: hidden; border: 1px solid var(--border); }
.quiz-progress .bar > i { display: block; height: 100%; background: linear-gradient(90deg, var(--primary), var(--accent)); transition: width .3s; }
.quiz-progress .txt { font-size: 12px; color: var(--muted); margin-top: 4px; }
.timer { font-family: var(--mono); font-size: 15px; font-weight: 700; letter-spacing: .5px; }
.timer.warn { color: var(--danger); }

.passage {
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
  white-space: pre-wrap;
  font-size: 14.5px;
  line-height: 1.85;
  max-height: 340px;
  overflow: auto;
}
.passage-label { font-size: 12px; color: var(--muted); margin-bottom: 8px; font-weight: 600; }

.q-meta { display: flex; gap: 6px; flex-wrap: wrap; margin-bottom: 10px; }
.q-prompt { font-size: 16px; font-weight: 600; line-height: 1.7; margin: 0 0 14px; }

.options { display: grid; gap: 9px; }
.opt {
  display: flex; gap: 11px; align-items: flex-start;
  border: 1px solid var(--border-strong);
  background: #fff;
  border-radius: var(--radius-sm);
  padding: 11px 14px;
  text-align: left;
  width: 100%;
  transition: .15s;
  line-height: 1.6;
}
.opt:hover:not(:disabled) { border-color: var(--primary); background: #fbfdff; }
.opt .key {
  flex: 0 0 24px; height: 24px; border-radius: 6px;
  background: var(--surface-2); border: 1px solid var(--border);
  display: grid; place-items: center; font-weight: 700; font-size: 13px;
}
.opt.selected { border-color: var(--primary); background: var(--primary-soft); }
.opt.selected .key { background: var(--primary); color: #fff; border-color: var(--primary); }
.opt.correct { border-color: var(--success); background: var(--success-soft); }
.opt.correct .key { background: var(--success); color: #fff; border-color: var(--success); }
.opt.wrong { border-color: var(--danger); background: var(--danger-soft); }
.opt.wrong .key { background: var(--danger); color: #fff; border-color: var(--danger); }
.opt:disabled { cursor: default; }

.feedback { margin-top: 16px; border-top: 1px dashed var(--border-strong); padding-top: 14px; }
.fb-head { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; margin-bottom: 10px; }
.fb-verdict { font-weight: 700; font-size: 15px; }
.fb-verdict.ok { color: var(--success); }
.fb-verdict.no { color: var(--danger); }
.fb-block { margin-top: 12px; }
.fb-block h4 { margin: 0 0 6px; font-size: 13px; color: var(--muted); font-weight: 700; letter-spacing: .5px; }
.fb-block p { margin: 0; font-size: 14.5px; color: var(--text-2); }

.vocab-table { width: 100%; border-collapse: collapse; font-size: 14px; }
.vocab-table td, .vocab-table th { border: 1px solid var(--border); padding: 6px 10px; text-align: left; }
.vocab-table th { background: var(--surface-2); font-size: 12px; color: var(--muted); }
.vocab-table td.pos { color: var(--accent); font-style: italic; white-space: nowrap; }
.vocab-table td.en { font-weight: 600; }

ul.plain { margin: 0; padding-left: 20px; }
ul.plain li { margin: 3px 0; font-size: 14.5px; color: var(--text-2); }

.answer-input { display: flex; gap: 10px; flex-wrap: wrap; align-items: center; }
.answer-input input { flex: 1; min-width: 180px; }

/* ---------- tables ---------- */
.table-wrap { overflow-x: auto; }
table.data { width: 100%; border-collapse: collapse; font-size: 14px; }
table.data th, table.data td { border: 1px solid var(--border); padding: 9px 12px; text-align: left; vertical-align: top; }
table.data th { background: var(--surface-2); font-size: 13px; color: var(--muted); white-space: nowrap; }
table.data tr:nth-child(even) td { background: #fcfdff; }

/* ---------- stats ---------- */
.stat {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 14px 16px; box-shadow: var(--shadow);
}
.stat .label { font-size: 12px; color: var(--muted); }
.stat .value { font-size: 24px; font-weight: 800; line-height: 1.3; }
.stat .sub { font-size: 12px; color: var(--muted); }

.bar-row { display: grid; grid-template-columns: 130px 1fr 96px; gap: 10px; align-items: center; margin-bottom: 9px; font-size: 13.5px; }
.bar-row .track { height: 9px; background: var(--surface-2); border: 1px solid var(--border); border-radius: 999px; overflow: hidden; }
.bar-row .track > i { display: block; height: 100%; background: var(--primary); border-radius: 999px; }
.bar-row .track > i.low { background: var(--danger); }
.bar-row .track > i.mid { background: var(--warn); }
.bar-row .num { text-align: right; color: var(--text-2); font-family: var(--mono); font-size: 12.5px; }

/* ---------- misc ---------- */
.empty { text-align: center; padding: 46px 16px; color: var(--muted); }
.empty .icon { font-size: 40px; }
.note {
  background: var(--warn-soft); border: 1px solid #f7e0b8; color: #92400e;
  border-radius: var(--radius-sm); padding: 10px 14px; font-size: 13.5px;
}
.note.blue { background: var(--primary-soft); border-color: #cdddff; color: var(--primary-dark); }
.modal-mask {
  position: fixed; inset: 0; background: rgba(15, 23, 42, .45);
  display: grid; place-items: center; z-index: 100; padding: 16px;
}
.modal {
  background: #fff; border-radius: var(--radius); max-width: 620px; width: 100%;
  max-height: 86vh; overflow: auto; padding: 22px; box-shadow: 0 20px 50px rgba(15, 23, 42, .25);
}
.modal h3 { margin: 0 0 10px; }
.paper-card { cursor: pointer; transition: .15s; border: 1px solid var(--border); background: var(--surface); border-radius: var(--radius); padding: 16px; }
.paper-card:hover { border-color: var(--primary); box-shadow: var(--shadow); transform: translateY(-1px); }
.paper-card .ic { font-size: 22px; }
.paper-card .nm { font-weight: 700; margin: 2px 0 4px; }
.paper-card .ds { font-size: 13px; color: var(--text-2); }
.paper-card .mt { font-size: 12px; color: var(--muted); margin-top: 8px; }

.qnav { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 12px; }
.qnav button {
  width: 32px; height: 32px; border-radius: 7px; border: 1px solid var(--border-strong);
  background: #fff; font-size: 12.5px; color: var(--text-2);
}
.qnav button.done { background: var(--primary-soft); border-color: #cdddff; color: var(--primary-dark); }
.qnav button.cur { background: var(--primary); border-color: var(--primary); color: #fff; font-weight: 700; }

.result-score { font-size: 42px; font-weight: 800; line-height: 1.1; }

.toast {
  position: fixed; left: 50%; bottom: 30px; transform: translateX(-50%);
  background: #1e293b; color: #fff; padding: 9px 18px; border-radius: 999px;
  font-size: 14px; z-index: 200; box-shadow: 0 8px 24px rgba(0,0,0,.2);
  animation: fade .2s ease;
}

.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); }

/* ---------- responsive ---------- */
@media (max-width: 860px) {
  .grid-3, .grid-4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .bar-row { grid-template-columns: 96px 1fr 78px; }
}
@media (max-width: 680px) {
  body { font-size: 14.5px; }
  .header-inner { padding: 9px 12px; gap: 8px; }
  .brand span.full { display: none; }
  .main-nav {
    display: none;
    position: absolute; top: 100%; left: 0; right: 0;
    background: #fff; border-bottom: 1px solid var(--border);
    flex-direction: column; gap: 0; padding: 6px; box-shadow: var(--shadow);
  }
  .main-nav.open { display: flex; }
  .main-nav button { text-align: left; border-radius: var(--radius-sm); padding: 10px 12px; }
  .nav-toggle { display: block; }
  .container { padding: 14px 12px 56px; }
  .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
  .quiz-head { top: 52px; padding: 10px 12px; }
  .bar-row { grid-template-columns: 84px 1fr 70px; font-size: 13px; }
  .passage { max-height: 240px; font-size: 14px; }
  .page-title { font-size: 19px; }
  .filter-group > label { min-width: 100%; }
}