:root {
  --bg: #f4f6f9;
  --surface: #ffffff;
  --surface-2: #f8fafc;
  --border: #e2e8f0;
  --text: #0f172a;
  --text-2: #475569;
  --text-3: #94a3b8;
  --brand: #0d9488;
  --brand-dark: #0f766e;
  --brand-soft: #ccfbf1;
  --accent: #2563eb;
  --accent-soft: #dbeafe;
  --amber: #d97706;
  --amber-soft: #fef3c7;
  --red: #dc2626;
  --red-soft: #fee2e2;
  --green: #16a34a;
  --green-soft: #dcfce7;
  --shadow: 0 1px 3px rgba(15, 23, 42, .08), 0 4px 16px rgba(15, 23, 42, .06);
  --radius: 14px;
  --radius-sm: 9px;
  --sidebar-w: 250px;
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }
html, body { margin: 0; padding: 0; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "PingFang SC", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
  font-size: 15px;
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
}

#app { display: flex; min-height: 100vh; }

/* ---------- Sidebar ---------- */
#sidebar {
  width: var(--sidebar-w);
  background: #0b1220;
  color: #cbd5e1;
  display: flex;
  flex-direction: column;
  position: fixed;
  top: 0; bottom: 0; left: 0;
  padding: 20px 14px;
}
.brand { display: flex; gap: 11px; align-items: center; padding: 4px 8px 20px; }
.brand-mark { font-size: 26px; }
.brand-title { font-weight: 700; color: #fff; font-size: 16px; letter-spacing: .2px; }
.brand-sub { font-size: 11px; color: #64748b; }

#nav { display: flex; flex-direction: column; gap: 4px; }
.nav-item {
  display: flex; align-items: center; gap: 11px;
  width: 100%; padding: 11px 12px; border: 0; border-radius: 10px;
  background: transparent; color: #cbd5e1; font-size: 14.5px; cursor: pointer;
  text-align: left; transition: background .15s, color .15s;
}
.nav-item:hover { background: rgba(255,255,255,.06); color: #fff; }
.nav-item.active { background: var(--brand); color: #fff; }
.nav-ico { font-size: 16px; width: 20px; text-align: center; }
.badge {
  margin-left: auto; background: var(--brand); color: #fff;
  font-size: 11px; font-weight: 700; padding: 2px 8px; border-radius: 99px;
}
.badge-red { background: var(--red); }
.sidebar-footer { margin-top: auto; padding: 12px 8px 0; }
.ai-status { font-size: 12px; color: #64748b; padding: 9px 11px; background: rgba(255,255,255,.04); border-radius: 9px; }

/* ---------- Main ---------- */
#main { flex: 1; margin-left: var(--sidebar-w); min-height: 100vh; }
.view { max-width: 1060px; margin: 0 auto; padding: 30px 34px 60px; }

h1 { font-size: 24px; margin: 0 0 6px; }
h2 { font-size: 19px; margin: 0 0 14px; }
h3 { font-size: 16px; margin: 0 0 10px; }
.muted { color: var(--text-2); }
.sub { color: var(--text-3); font-size: 13px; }
a { color: var(--accent); }

.page-head { display: flex; align-items: flex-start; justify-content: space-between; gap: 16px; margin-bottom: 22px; flex-wrap: wrap; }
.page-head .title-wrap h1 { margin-bottom: 4px; }

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex; align-items: center; gap: 8px;
  border: 1px solid var(--border); background: var(--surface); color: var(--text);
  padding: 9px 15px; border-radius: 10px; font-size: 14px; font-weight: 600;
  cursor: pointer; transition: all .15s; text-decoration: none;
}
.btn:hover { border-color: #cbd5e1; box-shadow: var(--shadow); }
.btn:disabled { opacity: .5; cursor: not-allowed; }
.btn-primary { background: var(--brand); border-color: var(--brand); color: #fff; }
.btn-primary:hover { background: var(--brand-dark); border-color: var(--brand-dark); }
.btn-accent { background: var(--accent); border-color: var(--accent); color: #fff; }
.btn-accent:hover { filter: brightness(1.06); }
.btn-danger { background: var(--red); border-color: var(--red); color: #fff; }
.btn-ghost { background: transparent; }
.btn-sm { padding: 6px 11px; font-size: 13px; border-radius: 8px; }
.btn-lg { padding: 13px 22px; font-size: 15px; border-radius: 12px; }

/* ---------- Cards & grids ---------- */
.card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); box-shadow: var(--shadow); padding: 20px;
}
.grid { display: grid; gap: 16px; }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }
@media (max-width: 900px) { .grid-3, .grid-4 { grid-template-columns: repeat(2, 1fr); } .grid-2 { grid-template-columns: 1fr; } }

.stat { text-align: left; }
.stat .stat-num { font-size: 30px; font-weight: 800; color: var(--text); }
.stat .stat-label { font-size: 13px; color: var(--text-3); }

/* ---------- Lesson list ---------- */
.lesson-item {
  display: flex; align-items: center; gap: 16px;
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 16px 18px; box-shadow: var(--shadow); cursor: pointer; transition: all .15s;
}
.lesson-item:hover { border-color: var(--brand); transform: translateY(-1px); }
.lesson-ico { font-size: 26px; }
.lesson-meta { margin-left: auto; display: flex; gap: 10px; align-items: center; }

.pill { font-size: 12px; font-weight: 600; padding: 3px 10px; border-radius: 99px; }
.pill-brand { background: var(--brand-soft); color: var(--brand-dark); }
.pill-accent { background: var(--accent-soft); color: var(--accent); }
.pill-amber { background: var(--amber-soft); color: var(--amber); }
.pill-red { background: var(--red-soft); color: var(--red); }
.pill-green { background: var(--green-soft); color: var(--green); }
.pill-gray { background: var(--surface-2); color: var(--text-2); border: 1px solid var(--border); }

/* ---------- Tabs ---------- */
.tabs { display: flex; gap: 6px; border-bottom: 1px solid var(--border); margin-bottom: 20px; flex-wrap: wrap; }
.tab {
  padding: 10px 15px; border: 0; background: transparent; cursor: pointer;
  font-size: 14.5px; font-weight: 600; color: var(--text-2);
  border-bottom: 2px solid transparent; margin-bottom: -1px;
}
.tab:hover { color: var(--text); }
.tab.active { color: var(--brand); border-bottom-color: var(--brand); }

/* ---------- Knowledge points ---------- */
.kp {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 18px 20px; box-shadow: var(--shadow); margin-bottom: 14px;
}
.kp-head { display: flex; align-items: center; gap: 10px; margin-bottom: 8px; flex-wrap: wrap; }
.kp-title { font-size: 16px; font-weight: 700; margin: 0; }
.imp { font-size: 11px; font-weight: 700; padding: 2px 9px; border-radius: 99px; text-transform: uppercase; letter-spacing: .3px; }
.imp-high { background: var(--red-soft); color: var(--red); }
.imp-medium { background: var(--amber-soft); color: var(--amber); }
.imp-low { background: var(--green-soft); color: var(--green); }
.kp-body { color: var(--text-2); }
.kp-mnemonic { margin-top: 10px; background: var(--amber-soft); border-left: 3px solid var(--amber); padding: 10px 13px; border-radius: 8px; font-size: 14px; }
.kp-mnemonic b { color: var(--amber); }
.kp-supplement { margin-top: 8px; background: #eff6ff; border-left: 3px solid var(--brand); padding: 9px 12px; border-radius: 8px; font-size: 13.5px; color: var(--text); line-height: 1.5; }
.kp-supplement b { color: var(--brand-dark); }
.kp-fig { margin-top: 12px; border: 1px solid var(--border); border-radius: 10px; overflow: hidden; }
.kp-fig img { max-width: 100%; display: block; }
.kp-fig .fig-cap { padding: 9px 13px; font-size: 13px; color: var(--text-2); background: var(--surface-2); }

/* ---------- Flashcards ---------- */
.flashcard-wrap { max-width: 640px; margin: 0 auto; }
.flashcard {
  background: var(--surface); border: 1px solid var(--border); border-radius: 18px;
  box-shadow: var(--shadow); min-height: 260px; padding: 30px;
  display: flex; flex-direction: column; align-items: center; justify-content: center;
  text-align: center; cursor: pointer; user-select: none; transition: all .2s;
}
.flashcard .card-label { font-size: 12px; text-transform: uppercase; letter-spacing: 1px; color: var(--text-3); margin-bottom: 14px; }
.flashcard .card-text { font-size: 20px; font-weight: 600; line-height: 1.5; }
.flashcard .card-text.answer { font-size: 17px; font-weight: 500; color: var(--brand-dark); }

/* ---------- Quiz ---------- */
.q-option {
  display: flex; align-items: flex-start; gap: 11px; width: 100%; text-align: left;
  background: var(--surface); border: 1.5px solid var(--border); border-radius: 11px;
  padding: 12px 14px; margin-bottom: 9px; cursor: pointer; font-size: 14.5px; transition: all .12s;
}
.q-option:hover { border-color: var(--accent); background: var(--accent-soft); }
.q-option .letter { font-weight: 800; color: var(--text-3); }
.q-option.correct { border-color: var(--green); background: var(--green-soft); }
.q-option.wrong { border-color: var(--red); background: var(--red-soft); }
.q-option.reveal-correct { border-color: var(--green); background: var(--green-soft); }
.q-expl { margin-top: 12px; background: var(--surface-2); border: 1px solid var(--border); border-radius: 10px; padding: 13px 15px; font-size: 14px; }
.q-expl.correct { background: var(--green-soft); }
.q-expl.wrong { background: var(--red-soft); }

/* ---------- Review ---------- */
.review-stage { max-width: 640px; margin: 0 auto; }
.review-grade { display: grid; grid-template-columns: repeat(4, 1fr); gap: 10px; margin-top: 20px; }
.grade-btn { padding: 13px 8px; border-radius: 11px; border: 1.5px solid var(--border); background: var(--surface); font-weight: 700; cursor: pointer; font-size: 13.5px; }
.grade-0 { color: var(--red); } .grade-0:hover { background: var(--red-soft); border-color: var(--red); }
.grade-1 { color: var(--amber); } .grade-1:hover { background: var(--amber-soft); border-color: var(--amber); }
.grade-2 { color: var(--green); } .grade-2:hover { background: var(--green-soft); border-color: var(--green); }
.grade-3 { color: var(--accent); } .grade-3:hover { background: var(--accent-soft); border-color: var(--accent); }

/* ---------- Mind map ---------- */
.mindmap { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 20px 24px; }
.mindmap ul { list-style: none; padding-left: 20px; margin: 4px 0; border-left: 1px dashed var(--border); }
.mindmap > ul { padding-left: 0; border-left: 0; }
.mindmap li { padding: 4px 0; }
.mindmap .node-title { font-weight: 700; color: var(--brand-dark); }
.mindmap .node-body { color: var(--text-2); font-size: 14px; }
/* ---- mind map v2: root -> branches -> leaf points ---- */
.mindmap2 { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 22px 24px; }
.mm-root { display: flex; align-items: center; gap: 10px; padding: 10px 16px; margin-bottom: 14px; background: linear-gradient(90deg, var(--brand), var(--brand-dark)); color: #fff; border-radius: 12px; font-weight: 700; font-size: 16px; box-shadow: 0 4px 14px rgba(0,0,0,.15); }
.mm-root-ico { font-size: 20px; }
.mm-root-sub { margin-left: auto; font-size: 12px; font-weight: 500; opacity: .9; }
.mindmap2 ul { list-style: none; margin: 0; padding-left: 18px; }
.mindmap2 ul.mm-children { border-left: 2px solid var(--brand); margin-left: 10px; padding-left: 14px; }
.mindmap2 ul.mm-root-pts { border-left: 0; padding-left: 0; margin-left: 0; }
.mm-summary { display: flex; align-items: center; gap: 6px; padding: 5px 8px; margin: 3px 0; border-radius: 6px; cursor: pointer; font-weight: 700; }
.mm-summary:hover { background: var(--surface-2); }
.mm-arrow { font-size: 11px; transition: transform .12s; color: var(--text-3); }
details.mm-details[open] .mm-arrow { transform: rotate(90deg); }
.mm-count { font-size: 11px; color: var(--text-3); background: var(--surface-2); padding: 1px 7px; border-radius: 99px; }
.mm-l1 > .mm-summary { color: var(--brand-dark); font-size: 15px; }
.mm-l2 > .mm-summary { color: var(--text); font-size: 14px; }
.mm-l3 > .mm-summary { color: var(--text-2); font-size: 13px; }
.mm-point { display: flex; align-items: center; gap: 8px; padding: 4px 8px; border-radius: 6px; cursor: pointer; }
.mm-point:hover { background: var(--surface-2); }
.mm-dot { width: 8px; height: 8px; border-radius: 50%; flex-shrink: 0; }
.mm-dot.high { background: var(--red); }
.mm-dot.medium { background: var(--amber); }
.mm-dot.low { background: var(--text-3); }
.mm-point-title { font-weight: 600; color: var(--text); }
.mm-imp { font-size: 10px; font-weight: 700; padding: 1px 6px; border-radius: 99px; }
.mm-imp.high { background: var(--red); color: #fff; }
.mm-imp.medium { background: var(--amber); color: #fff; }
.mm-imp.low { background: var(--text-3); color: #fff; }

/* ---------- Upload dropzone ---------- */
.dropzone {
  border: 2px dashed #cbd5e1; border-radius: 16px; padding: 52px 24px;
  text-align: center; cursor: pointer; background: var(--surface); transition: all .15s;
}
.dropzone:hover, .dropzone.drag { border-color: var(--brand); background: var(--brand-soft); }
.dropzone .dz-ico { font-size: 40px; }
.dropzone input { display: none; }

/* ---------- Slides preview ---------- */
.slide-card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 16px; margin-bottom: 12px; }
.slide-head { display: flex; align-items: center; justify-content: space-between; margin-bottom: 8px; }
.slide-num { font-weight: 700; color: var(--brand); }
.slide-text { white-space: pre-wrap; color: var(--text-2); font-size: 13.5px; max-height: 160px; overflow: auto; }
.slide-images { display: flex; gap: 10px; flex-wrap: wrap; margin-top: 10px; }
.slide-images img { max-height: 120px; border-radius: 8px; border: 1px solid var(--border); }
.slide-notes { margin-top: 8px; font-size: 13px; color: var(--amber); background: var(--amber-soft); padding: 8px 11px; border-radius: 8px; white-space: pre-wrap; }

/* ---------- Progress ---------- */
.progress-bar { height: 10px; background: var(--border); border-radius: 99px; overflow: hidden; }
.progress-fill { height: 100%; background: var(--brand); border-radius: 99px; transition: width .3s; }
.step-row { display: flex; align-items: center; gap: 12px; padding: 10px 0; border-bottom: 1px solid var(--border); font-size: 14px; }
.step-row:last-child { border-bottom: 0; }
.step-ico { width: 22px; text-align: center; }

/* ---------- Mistake ---------- */
.mistake-item { border-left: 4px solid var(--red); }

/* ---------- Settings ---------- */
.field { margin-bottom: 18px; }
.field label { display: block; font-size: 13.5px; font-weight: 600; margin-bottom: 6px; color: var(--text-2); }
.field input, .field select, .field textarea {
  width: 100%; padding: 10px 12px; border: 1.5px solid var(--border); border-radius: 9px;
  font-size: 14px; font-family: inherit; background: var(--surface); color: var(--text);
}
.field input:focus, .field select:focus { outline: none; border-color: var(--brand); }
.field .hint { font-size: 12px; color: var(--text-3); margin-top: 5px; }

/* ---------- Modal ---------- */
.modal-backdrop {
  position: fixed; inset: 0; background: rgba(15,23,42,.5); display: flex;
  align-items: center; justify-content: center; z-index: 100; padding: 20px;
}
.modal {
  background: var(--surface); border-radius: 18px; box-shadow: 0 20px 60px rgba(0,0,0,.25);
  width: 100%; max-width: 720px; max-height: 90vh; overflow: auto; padding: 28px;
}
.modal h2 { margin-bottom: 16px; }

/* ---------- Toast ---------- */
#toast-wrap { position: fixed; bottom: 22px; right: 22px; display: flex; flex-direction: column; gap: 10px; z-index: 200; }
.toast {
  background: #0f172a; color: #fff; padding: 13px 18px; border-radius: 11px;
  box-shadow: var(--shadow); font-size: 14px; max-width: 360px; animation: slideIn .2s ease;
}
.toast.error { background: var(--red); }
.toast.success { background: var(--green); }
@keyframes slideIn { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: none; } }

.empty {
  text-align: center; padding: 60px 20px; color: var(--text-3);
}
.empty .empty-ico { font-size: 46px; margin-bottom: 12px; }
.loading { text-align: center; padding: 30px; color: var(--text-3); }
.spinner {
  width: 26px; height: 26px; border: 3px solid var(--border); border-top-color: var(--brand);
  border-radius: 50%; animation: spin .7s linear infinite; margin: 0 auto 12px;
}
@keyframes spin { to { transform: rotate(360deg); } }

/* ---------- Progress / time stats ---------- */
.chart { display: flex; gap: 10px; align-items: flex-end; height: 170px; padding-top: 8px; }
.chart-col { flex: 1; display: flex; flex-direction: column; align-items: center; justify-content: flex-end; height: 100%; }
.chart-bar { width: 72%; max-width: 46px; background: linear-gradient(180deg, var(--brand), var(--brand-dark)); border-radius: 6px 6px 2px 2px; min-height: 3px; transition: height .3s; }
.chart-label { font-size: 11px; color: var(--text-3); margin-top: 6px; }
.chart-label.chart-today { color: var(--brand); font-weight: 700; }
.chart-val { font-size: 10px; color: var(--text-3); min-height: 13px; }
.break-row { display: flex; align-items: center; gap: 12px; margin-bottom: 10px; }
.break-label { width: 130px; font-size: 13.5px; color: var(--text-2); }
.lp-row { padding: 13px 2px; border-bottom: 1px solid var(--border); cursor: pointer; }
.lp-row:last-child { border-bottom: 0; }
.lp-row:hover .lp-title { color: var(--brand); }
.lp-top { display: flex; justify-content: space-between; align-items: center; margin-bottom: 7px; }
.lp-title { font-weight: 600; }
.lp-pct { font-weight: 800; color: var(--brand-dark); }
.lp-meta { font-size: 12.5px; }
.stat-click { cursor: pointer; transition: all .15s; }
.stat-click:hover { border-color: var(--brand); transform: translateY(-1px); }

/* ---------- Search ---------- */
.search-select { padding: 9px 12px; border: 1.5px solid var(--border); border-radius: 9px; font-size: 14px; background: var(--surface); color: var(--text); font-family: inherit; }
.search-select:focus { outline: none; border-color: var(--brand); }
.search-row { display: flex; align-items: center; gap: 12px; padding: 11px 4px; border-bottom: 1px solid var(--border); cursor: pointer; }
.search-row:last-child { border-bottom: 0; }
.search-row:hover { background: var(--surface-2); }
.search-ico { font-size: 18px; width: 24px; text-align: center; }

/* ---------- Key-point highlight & figures ---------- */
mark.hl { background: #fde68a; color: #1f2937; font-weight: 700; padding: 0 2px; border-radius: 3px; }
mark.hl.cloze-hidden { background: #e2e8f0; color: #64748b; border-bottom: 2px solid var(--brand); cursor: pointer; }
mark.hl.cloze-revealed { background: #bbf7d0; border-bottom: 2px solid var(--green); }
mark.hl.cloze-wrong { background: #fecaca; border-bottom: 2px solid var(--red); }
.kp-section.recalling .kp-subtitle { text-decoration: underline; text-underline-offset: 3px; }
.recall-tip { font-size: 13px; color: var(--text-2); background: var(--surface-2); padding: 8px 12px; border-radius: 8px; margin-bottom: 8px; }
.recall-rate .btn { padding: 4px 10px; font-size: 13px; }
.recall-btn[data-state="active"] { color: var(--red); }
.kp-figs { display: flex; gap: 12px; flex-wrap: wrap; margin-top: 12px; }
.kp-fig { margin: 0; max-width: 680px; border: 1px solid var(--border); border-radius: 10px; overflow: hidden; background: var(--surface-2); }
.kp-fig img { width: 100%; max-height: 520px; object-fit: contain; display: block; cursor: zoom-in; background: #fff; }
.kp-fig-wrap { position: relative; }
.kp-crop-badge { position: absolute; top: 8px; left: 8px; background: rgba(37,99,235,.85); color: #fff; font-size: 10.5px; padding: 2px 8px; border-radius: 99px; }
.kp-crop-btn { padding: 1px 6px; font-size: 11px; margin-left: 6px; }
/* crop picker overlay */
.crop-mask { position: absolute; border: 2px solid var(--brand); background: rgba(37,99,235,.12); cursor: move; box-shadow: 0 0 0 9999px rgba(0,0,0,.35); }
.crop-mask .crop-handle { position: absolute; width: 14px; height: 14px; background: #fff; border: 2px solid var(--brand); border-radius: 3px; }
.crop-mask .crop-handle.se { right: -7px; bottom: -7px; cursor: nwse-resize; }
.crop-mask .crop-handle.nw { left: -7px; top: -7px; cursor: nwse-resize; }
.kp-fig figcaption { padding: 7px 11px; font-size: 12px; color: var(--text-2); line-height: 1.4; }
.kp-filters { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 14px; }
.chip { padding: 7px 14px; border: 1.5px solid var(--border); border-radius: 99px; background: var(--surface); color: var(--text-2); font-size: 13.5px; font-weight: 600; cursor: pointer; transition: all .12s; }
.chip:hover { border-color: var(--brand); color: var(--brand); }
.chip.active { background: var(--brand); border-color: var(--brand); color: #fff; }
.kp-group { margin-bottom: 20px; }
.kp-group-title { font-size: 16px; font-weight: 800; margin: 0 0 8px; color: var(--text); }
.kp-section { padding: 14px 0; border-bottom: 1px solid var(--border); }
.kp-section:last-child { border-bottom: 0; padding-bottom: 2px; }
.kp-section:first-child { padding-top: 8px; }
.kp-subhead { display: flex; align-items: center; gap: 10px; margin-bottom: 8px; flex-wrap: wrap; }
.kp-subtitle { font-size: 15px; font-weight: 700; color: var(--text); }
.tree-l1 { font-size: 17px; font-weight: 800; margin: 22px 0 10px; color: var(--text); }
.tree-l2 { font-size: 15px; font-weight: 700; margin: 16px 0 6px; color: var(--brand-dark); padding-left: 12px; border-left: 3px solid var(--brand); }
.tree-l3 { font-size: 13px; font-weight: 600; margin: 12px 0 4px; color: var(--text-2); padding-left: 12px; }
/* Collapsible key-point groups (default hidden) */
details.kp-group { margin: 4px 0; }
details.kp-group summary.kp-summary { cursor: pointer; list-style: none; user-select: none; }
details.kp-group summary.kp-summary::-webkit-details-marker { display: none; }
details.kp-group[open] > summary .kp-arrow { transform: rotate(90deg); }
.kp-arrow { display: inline-block; transition: transform .15s; color: var(--text-3); font-size: 13px; width: 14px; }
details.kp-group > summary.tree-l1 { margin: 16px 0 8px; padding: 6px 10px; border-radius: 8px; }
details.kp-group > summary.tree-l1:hover { background: var(--surface-2); }
details.kp-group > summary.tree-l2 { margin: 8px 0 4px; padding: 4px 8px; border-radius: 6px; }
details.kp-group > summary.tree-l2:hover { background: var(--surface-2); }
details.kp-group > summary.tree-l3 { margin: 6px 0 3px; padding: 3px 8px; border-radius: 6px; }
details.kp-group > summary.tree-l3:hover { background: var(--surface-2); }
details.kp-group > .tree-l2, details.kp-group > .tree-l3, details.kp-group > .card { margin-left: 10px; }
.r-q { font-size: 15px; color: var(--text-2); font-weight: 500; margin-bottom: 12px; text-align: left; }
.r-divider { border-top: 1px dashed var(--border); margin: 12px 0; }
.r-a { font-size: 17px; color: var(--brand-dark); font-weight: 600; text-align: left; }
/* Knowledge navigator */
.nav-l1 { font-size: 14px; font-weight: 800; margin: 12px 0 4px; color: var(--text); }
.nav-l2 { font-size: 13px; font-weight: 700; margin: 8px 0 2px; color: var(--brand-dark); }
.nav-l3 { font-size: 12px; font-weight: 600; margin: 6px 0 2px; color: var(--text-2); }
.nav-children { margin-left: 12px; }
.nav-points { margin-left: 12px; }
.nav-point { display: flex; align-items: center; gap: 8px; padding: 5px 8px; border-radius: 6px; cursor: pointer; }
.nav-point:hover { background: var(--surface-2); }
.nav-point-title { font-size: 13px; }
.nav-arrow { color: var(--text-3); font-size: 13px; width: 14px; }
.kp-flash { animation: kpFlash 2s ease; border-radius: 8px; }
@keyframes kpFlash { 0% { background: var(--brand-soft); } 100% { background: transparent; } }
.kp-fig-toggle { margin-top: 10px; }
.grade-btn { display: flex; flex-direction: column; align-items: center; gap: 3px; line-height: 1.3; }
.g-int { font-weight: 400; font-size: 11.5px; opacity: .85; }
.g-key { font-size: 10px; font-weight: 700; opacity: .5; border: 1px solid currentColor; border-radius: 4px; padding: 0 5px; }

/* Immersive reading mode for Key Points */
body.immersive #sidebar { display: none !important; }
body.immersive #main { margin-left: 0 !important; display: flex; justify-content: center; }
body.immersive #view { width: 100%; max-width: 900px; padding: 26px 24px 60px; }
body.immersive .page-head { margin-bottom: 10px; }
body.immersive .page-head .title-wrap h1 { font-size: 26px; }
body.immersive .kp-group > summary.tree-l1 { font-size: 22px; }

/* ---------------- Interactive desk pet ---------------- */
#pet {
  position: fixed;
  bottom: 16px;
  right: 16px;
  width: 96px;
  z-index: 60;
  cursor: grab;
  user-select: none;
  -webkit-user-select: none;
  touch-action: none;
  opacity: 0;
  transform: translateY(36px);
  transition: opacity .25s ease, transform .25s ease;
  pointer-events: none;
}
#pet.show {
  opacity: 1;
  transform: translateY(0);
  pointer-events: auto;
}
#pet img {
  width: 100%;
  height: auto;
  display: block;
  filter: drop-shadow(0 6px 12px rgba(0,0,0,.22));
  transition: transform .18s ease;
}
#pet:hover img { transform: scale(1.05); }
#pet.dragging { cursor: grabbing; }
#pet.dragging img { transform: scale(1.08); }
#pet.pop img { animation: pet-pop .4s ease; }
@keyframes pet-pop {
  0% { transform: scale(1); }
  35% { transform: scale(1.15) rotate(-6deg); }
  70% { transform: scale(.96) rotate(4deg); }
  100% { transform: scale(1); }
}
#pet-bubble {
  position: absolute;
  bottom: calc(100% + 8px);
  right: 0;
  width: max-content;
  max-width: 220px;
  background: #fff;
  border: 1.5px solid var(--border);
  border-radius: 12px;
  padding: 8px 11px;
  font-size: 12.5px;
  line-height: 1.4;
  color: var(--text);
  box-shadow: 0 4px 16px rgba(0,0,0,.15);
  margin-bottom: 6px;
}
#pet-bubble:after {
  content: "";
  position: absolute;
  bottom: -7px;
  right: 22px;
  width: 12px; height: 12px;
  background: #fff;
  border-right: 1.5px solid var(--border);
  border-bottom: 1.5px solid var(--border);
  transform: rotate(45deg);
}

#pet-timer {
  position: absolute;
  bottom: calc(100% + 6px);
  right: 0;
  background: #fff;
  border: 1.5px solid var(--border);
  border-radius: 10px;
  padding: 6px 9px;
  font-size: 12px;
  color: var(--text);
  box-shadow: 0 4px 14px rgba(0,0,0,.12);
  text-align: right;
  line-height: 1.5;
}
#pet-today { font-weight: 600; color: var(--text-2); white-space: nowrap; }
#pet-pomo-btn { margin-top: 4px; padding: 2px 8px; font-size: 11.5px; }
#pet-pomo-btn.running { color: var(--red); border-color: var(--red); }
#pet-pomo-mini {
  position: fixed;
  bottom: 12px;
  right: 12px;
  z-index: 61;
  background: var(--surface);
  border: 1.5px solid var(--brand);
  border-radius: 20px;
  padding: 5px 12px;
  font-size: 12.5px;
  font-weight: 700;
  color: var(--brand);
  box-shadow: 0 4px 14px rgba(0,0,0,.18);
  cursor: pointer;
}