:root {
  --brand: #2f6bff;
  --brand-strong: #1f56db;
  --brand-soft: #f0f5ff;
  --ink: #182230;
  --muted: #647184;
  --subtle: #98a2b3;
  --canvas: #f7f8fa;
  --surface: #ffffff;
  --line: #e6eaf0;
  --success: #1f9d68;
  --warning: #b7791f;
  --danger: #d64545;
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 18px;
  --shadow-sm: 0 1px 3px rgba(24, 34, 48, .06);
  --shadow-md: 0 8px 24px rgba(24, 34, 48, .08);
  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 20px;
  --space-6: 24px;
  --space-8: 32px;
}

* { box-sizing: border-box; }
html { background: var(--canvas); }
body { margin: 0; font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", sans-serif; color: var(--ink); background: var(--canvas); line-height: 1.65; }
button, input, textarea, select { font: inherit; }
button { -webkit-tap-highlight-color: transparent; }
.wrap { width: min(100% - 32px, 960px); margin: 0 auto; padding-bottom: 96px; }
header { padding: 28px 4px 20px; }
header h1 { margin: 0; font-size: clamp(24px, 4vw, 32px); line-height: 1.25; letter-spacing: -.02em; }
header p { margin: 8px 0 0; color: var(--muted); font-size: 15px; }
.badge { display: inline-flex; margin-top: 12px; padding: 4px 10px; border-radius: 999px; color: var(--brand-strong); background: var(--brand-soft); font-size: 12px; }
.tabs { display: grid; grid-template-columns: repeat(3, 1fr); gap: 4px; position: sticky; top: 0; z-index: 5; padding: 6px; background: rgba(247,248,250,.94); backdrop-filter: blur(14px); border-bottom: 1px solid var(--line); }
.tab { min-height: 44px; display: grid; place-items: center; padding: 8px 6px; border: 0; border-radius: var(--radius-sm); color: var(--muted); background: transparent; cursor: pointer; font-size: 14px; font-weight: 600; }
.tab:hover { color: var(--brand); background: var(--brand-soft); }
.tab.active { color: var(--brand-strong); background: var(--surface); box-shadow: var(--shadow-sm); }
.pane { padding: var(--space-6) 0; display: none; }
.pane.active { display: block !important; }
.section-head { display: flex; justify-content: space-between; align-items: end; gap: var(--space-4); margin-bottom: var(--space-4); }
.section-head h2 { margin: 0; font-size: 22px; line-height: 1.3; }
.section-head p { margin: 4px 0 0; color: var(--muted); font-size: 14px; }
.card-box, .term-card { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius-lg); box-shadow: var(--shadow-sm); }
.card-box { padding: var(--space-6); margin-bottom: var(--space-4); }
.card-box h2 { margin: 0 0 var(--space-3); font-size: 18px; line-height: 1.35; }
.hero-card { display: grid; grid-template-columns: 1fr auto; gap: var(--space-6); align-items: center; padding: clamp(20px, 4vw, 32px); color: #fff; background: linear-gradient(135deg, #244fc7, var(--brand)); border: 0; box-shadow: var(--shadow-md); }
.hero-card h2 { margin: 0; color: #fff; font-size: clamp(22px, 4vw, 28px); }
.hero-card p { margin: 8px 0 0; color: rgba(255,255,255,.82); }
.hero-card .btn { width: auto; min-width: 132px; color: var(--brand-strong); background: #fff; }
.quick-grid, .stat-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: var(--space-3); }
.quick-action { padding: var(--space-4); text-align: left; border: 1px solid var(--line); border-radius: var(--radius-md); color: var(--ink); background: var(--surface); cursor: pointer; box-shadow: var(--shadow-sm); }
.quick-action:hover { border-color: var(--brand); transform: translateY(-1px); }
.quick-action b { display: block; margin-bottom: 3px; font-size: 15px; }
.quick-action span { color: var(--muted); font-size: 13px; }
label { display: block; margin: 0 0 var(--space-2); color: var(--muted); font-size: 13px; font-weight: 600; }
.grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: var(--space-4); }
input, textarea, select { width: 100%; border: 1px solid var(--line); border-radius: var(--radius-md); padding: 12px 14px; color: var(--ink); background: #fbfcfe; transition: border-color .18s, box-shadow .18s, background .18s; }
textarea { min-height: 156px; resize: vertical; }
input::placeholder, textarea::placeholder { color: var(--subtle); }
input:focus, textarea:focus, select:focus { outline: none; border-color: var(--brand); background: #fff; box-shadow: 0 0 0 3px rgba(47,107,255,.14); }
.btn, .btn-sm { border: 1px solid transparent; border-radius: var(--radius-md); cursor: pointer; transition: transform .18s, background .18s, border-color .18s; }
.btn { width: 100%; padding: 12px 16px; color: #fff; background: var(--brand); font-weight: 700; }
.btn:hover { background: var(--brand-strong); transform: translateY(-1px); }
.btn:disabled { opacity: .6; cursor: wait; transform: none; }
.btn-sm { display: inline-flex; align-items: center; justify-content: center; min-height: 40px; padding: 8px 14px; color: var(--brand-strong); background: #fff; border-color: #b9caff; font-size: 14px; font-weight: 600; }
.btn-sm:hover { border-color: var(--brand); background: var(--brand-soft); }
.btn-row { display: flex; flex-wrap: wrap; gap: var(--space-3); margin-top: var(--space-4); }
.btn-row > .btn { flex: 1 1 220px; width: auto; }
.btn-know { color: #147a4f; border-color: #a9dfc7; background: #effbf5; }
.btn-half { color: #986515; border-color: #f0d39b; background: #fff9ed; }
.btn-unk { color: #b33333; border-color: #efb4b4; background: #fff3f3; }
.hint { margin: 6px 0 0; color: var(--muted); font-size: 13px; }
.term-card { padding: var(--space-5); margin-bottom: var(--space-3); }
.term-head { display: flex; justify-content: space-between; align-items: start; gap: var(--space-3); }
.term-name { font-size: 20px; font-weight: 750; line-height: 1.35; }
.cat-tag { flex: 0 0 auto; padding: 4px 9px; border-radius: 999px; color: var(--brand-strong); background: var(--brand-soft); font-size: 12px; font-weight: 700; }
.field { margin-top: var(--space-4); font-size: 15px; }
.field .k { display: block; margin-bottom: var(--space-1); color: var(--muted); font-size: 12px; font-weight: 600; }
.plain { padding: 12px 14px; border-radius: var(--radius-md); color: #26364d; background: var(--brand-soft); }
.short-meaning { font-size: 16px; line-height: 1.8; }
.detail-meaning { white-space: pre-wrap; line-height: 1.85; }
.ph { color: var(--subtle); font-size: 14px; font-style: italic; }
.lib-item { display: flex; justify-content: space-between; align-items: center; gap: var(--space-3); padding: 14px 16px; margin-bottom: var(--space-2); border: 1px solid var(--line); border-radius: var(--radius-md); background: var(--surface); cursor: pointer; box-shadow: var(--shadow-sm); }
.lib-item:hover, .lib-item:focus-visible { border-color: var(--brand); background: var(--brand-soft); }
.lib-item .t { font-size: 16px; font-weight: 700; }
.lib-item .c { color: var(--muted); font-size: 12px; }
.loading, .empty, .err { padding: var(--space-6); border-radius: var(--radius-md); text-align: center; }
.loading { color: var(--brand-strong); background: var(--brand-soft); }
.empty { color: var(--muted); background: #f1f3f6; }
.err { color: #a83333; background: #fff1f1; border: 1px solid #f2c4c4; }
.status { min-height: 20px; margin-top: var(--space-3); font-size: 13px; }
.status.success { color: var(--success); }
.status.error { color: var(--danger); }
.stat-grid { grid-template-columns: repeat(3, 1fr); }
.stat { padding: var(--space-4); text-align: center; border: 1px solid var(--line); border-radius: var(--radius-md); background: var(--surface); }
.stat b { display: block; color: var(--brand-strong); font-size: 24px; line-height: 1.2; }
.stat span { color: var(--muted); font-size: 12px; }
.source-row { margin-top: var(--space-2); }
.source-toggle { width: 100%; justify-content: flex-start; text-align: left; }
.source-body { padding: 12px 14px; margin-top: var(--space-2); border-radius: var(--radius-md); color: var(--muted); background: #f8fafc; font-size: 14px; }
.source-body.collapsed { display: none; }
.paper-title { margin: var(--space-3) 0; }
.paper-translation { margin-top: var(--space-3); }
.paper-group { padding: 14px 16px; margin: var(--space-3) 0; border: 1px solid var(--line); border-radius: var(--radius-md); background: var(--surface); }
.paper-group summary { color: var(--ink); font-size: 16px; font-weight: 750; cursor: pointer; }
.paper-region h3 { margin: var(--space-3) 0 var(--space-2); color: var(--muted); font-size: 13px; }
.paper-text { padding: var(--space-5); border: 1px solid var(--line); border-radius: var(--radius-md); background: #fff; white-space: pre-wrap; line-height: 2; }
.paper-term { padding: 0 3px; border: 0; border-bottom: 2px solid var(--brand); color: var(--brand-strong); background: var(--brand-soft); cursor: pointer; font: inherit; }
.practice-feedback { padding: 12px 14px; margin-top: var(--space-3); border-radius: var(--radius-md); font-weight: 700; }
.practice-feedback.ok { color: #147a4f; background: #effbf5; }
.practice-feedback.no { color: #b33333; background: #fff3f3; }
.writing-tip { padding-top: var(--space-4); margin-top: var(--space-4); border-top: 1px solid var(--line); }
.writing-tip:first-child { padding-top: 0; margin-top: 0; border-top: 0; }
.tip-more { margin-top: var(--space-2); }
.tip-more summary { color: var(--brand-strong); cursor: pointer; font-size: 13px; }
.tip-why { padding: 12px 14px; margin-top: var(--space-2); border-radius: var(--radius-md); background: #f8fafc; }
.tip-why-part + .tip-why-part { padding-top: var(--space-3); margin-top: var(--space-3); border-top: 1px solid var(--line); }
.tip-why-label { color: var(--brand-strong); font-size: 13px; }
.onboarding { position: fixed; inset: 0; z-index: 20; display: flex; align-items: center; justify-content: center; padding: var(--space-5); background: rgba(24,34,48,.45); }
.onboarding.hide { display: none; }
.onboarding-box { width: min(100%, 460px); padding: var(--space-8); border-radius: var(--radius-lg); background: var(--surface); box-shadow: var(--shadow-md); }
.onboarding-box h2 { margin: 0; font-size: 24px; }
.onboarding-box p { color: var(--muted); }
.onboarding-actions { display: flex; gap: var(--space-3); align-items: center; }
.onboarding-actions .btn { flex: 1; }
.toast { position: fixed; left: 50%; bottom: 24px; z-index: 30; max-width: calc(100% - 32px); padding: 10px 16px; border-radius: 999px; color: #fff; background: #182230; box-shadow: var(--shadow-md); transform: translateX(-50%); }
footer { padding: var(--space-6) 0; color: var(--subtle); text-align: center; font-size: 12px; }
footer button { padding: 0; border: 0; color: var(--muted); background: none; cursor: pointer; text-decoration: underline; }
.modal { position: fixed; inset: 0; z-index: 25; display: grid; place-items: center; padding: var(--space-5); background: rgba(24,34,48,.45); }
.modal.hide { display: none; }
.modal-box { width: min(100%, 560px); max-height: min(80vh, 640px); overflow: auto; padding: var(--space-6); border-radius: var(--radius-lg); background: #fff; box-shadow: var(--shadow-md); }
.modal-box h2 { margin-top: 0; }
.modal-close { float: right; border: 0; color: var(--muted); background: none; cursor: pointer; font-size: 20px; }
:focus-visible { outline: 3px solid rgba(47,107,255,.45); outline-offset: 2px; }
@media (min-width: 720px) { .pane { padding: var(--space-8) 4px; } .two-col { display: grid; grid-template-columns: 1.2fr .8fr; gap: var(--space-4); align-items: start; } }
@media (max-width: 600px) { .wrap { width: min(100% - 20px, 960px); } header { padding-top: 20px; } .tabs { grid-template-columns: repeat(3, minmax(0, 1fr)); } .tab { padding: 8px 2px; font-size: 12px; } .grid, .quick-grid { grid-template-columns: 1fr; } .hero-card { grid-template-columns: 1fr; } .hero-card .btn { width: 100%; } .card-box, .term-card { padding: var(--space-4); } .btn, .btn-sm { min-height: 44px; } .onboarding-actions { flex-direction: column; } .onboarding-actions .btn, .onboarding-actions .btn-sm { width: 100%; } }
@media (prefers-reduced-motion: reduce) { *, *::before, *::after { scroll-behavior: auto !important; transition-duration: .01ms !important; animation-duration: .01ms !important; } }