/* ===== 基础变量 ===== */
:root {
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --primary-light: #dbeafe;
  --success: #16a34a;
  --warning: #d97706;
  --danger: #dc2626;
  --bg: #f8fafc;
  --surface: #ffffff;
  --text: #0f172a;
  --text-secondary: #475569;
  --border: #e2e8f0;
  --shadow: 0 1px 3px rgba(0,0,0,0.08), 0 1px 2px rgba(0,0,0,0.06);
  --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.08), 0 4px 6px -2px rgba(0,0,0,0.04);
  --radius: 10px;
  --radius-sm: 6px;
  --transition: 0.2s ease;
  --sidebar-width: 260px;
  --top-height: 64px;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
html, body { height: 100%; font-family: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif; background: var(--bg); color: var(--text); }

.app-container { display: flex; height: 100vh; overflow: hidden; }

/* ===== Sidebar ===== */
.sidebar {
  width: var(--sidebar-width);
  background: var(--surface);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  flex-shrink: 0;
  z-index: 20;
}
.sidebar-header { padding: 20px 18px 14px; border-bottom: 1px solid var(--border); }
.sidebar-header h1 { font-size: 18px; font-weight: 700; color: var(--primary); display: flex; align-items: center; gap: 8px; }
.subtitle { font-size: 12px; color: var(--text-secondary); margin-top: 4px; letter-spacing: 0.5px; }

.nav-menu { flex: 1; overflow-y: auto; padding: 10px 0; }
.nav-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 18px;
  cursor: pointer;
  transition: background var(--transition), color var(--transition);
  border-left: 3px solid transparent;
  font-size: 14px;
}
.nav-item:hover { background: var(--primary-light); color: var(--primary); }
.nav-item.active { background: var(--primary-light); color: var(--primary); border-left-color: var(--primary); font-weight: 600; }
.nav-item .count { font-size: 12px; color: var(--text-secondary); background: var(--bg); padding: 2px 8px; border-radius: 999px; }
.nav-item.active .count { background: var(--primary); color: #fff; }

.sidebar-footer { padding: 14px 18px; border-top: 1px solid var(--border); font-size: 12px; color: var(--text-secondary); }

/* ===== Main Content ===== */
.main-content { flex: 1; display: flex; flex-direction: column; min-width: 0; overflow: hidden; }

/* Top Bar - 两行布局 */
.top-bar {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  padding: 14px 24px 10px;
  flex-shrink: 0;
  gap: 10px;
}
.top-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 28px;
}
.breadcrumb { font-size: 18px; font-weight: 700; color: var(--text); }
.result-count { font-size: 13px; color: var(--text-secondary); font-weight: 500; }

/* Filter Bar */
.filter-bar { display: flex; flex-wrap: wrap; gap: 16px 24px; align-items: flex-start; }
.filter-group {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
}
.filter-group-label {
  font-size: 12px;
  font-weight: 600;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  white-space: nowrap;
  padding: 4px 0;
}
.filter-chip {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 5px 12px; font-size: 13px; border-radius: var(--radius-sm);
  border: 1px solid var(--border); background: var(--bg); cursor: pointer; transition: var(--transition);
  color: var(--text-secondary);
  white-space: nowrap;
}
.filter-chip:hover { border-color: var(--primary); color: var(--primary); background: var(--primary-light); }
.filter-chip.active { background: var(--primary); color: #fff; border-color: var(--primary); font-weight: 500; }
.filter-chip .clear { display: none; font-weight: 700; margin-left: 2px; }
.filter-chip.active .clear { display: inline; }

/* ===== Content Area ===== */
.content-area { flex: 1; overflow-y: auto; padding: 20px 24px; }
.loading { display: flex; flex-direction: column; align-items: center; justify-content: center; height: 60vh; gap: 16px; color: var(--text-secondary); }
.spinner { width: 40px; height: 40px; border: 3px solid var(--border); border-top-color: var(--primary); border-radius: 50%; animation: spin 0.8s linear infinite; }
@keyframes spin { to { transform: rotate(360deg); } }

/* ===== Question Card ===== */
.question-list { display: flex; flex-direction: column; gap: 16px; max-width: 960px; }
.question-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  overflow: hidden;
  transition: box-shadow var(--transition), transform var(--transition);
}
.question-card:hover { box-shadow: var(--shadow-lg); transform: translateY(-1px); }

.card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 16px;
  background: linear-gradient(90deg, var(--primary-light), transparent);
  border-bottom: 1px solid var(--border);
}
.card-meta { display: flex; gap: 8px; align-items: center; }
.badge {
  font-size: 11px; font-weight: 600; padding: 3px 8px; border-radius: var(--radius-sm); text-transform: uppercase; letter-spacing: 0.4px;
}
.badge-year { background: #e0e7ff; color: #3730a3; }
.badge-type { background: #dcfce7; color: #166534; }
.badge-paper { background: #fef9c3; color: #854d0e; }
.badge-score { background: #fee2e2; color: #991b1b; }

.card-body { padding: 16px; font-size: 15px; line-height: 1.75; }
.card-body .q-index { font-weight: 700; color: var(--primary); margin-right: 6px; }

.card-actions { display: flex; gap: 10px; padding: 10px 16px; border-top: 1px solid var(--border); background: #fafafa; }
.btn {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 6px 14px; font-size: 13px; border-radius: var(--radius-sm); border: 1px solid var(--border);
  background: #fff; cursor: pointer; transition: var(--transition); color: var(--text-secondary);
}
.btn:hover { border-color: var(--primary); color: var(--primary); background: var(--primary-light); }
.btn-primary { background: var(--primary); color: #fff; border-color: var(--primary); }
.btn-primary:hover { background: var(--primary-dark); color: #fff; }

/* ===== Answer / Analysis ===== */
.card-detail {
  padding: 0 16px 16px;
  border-top: 1px dashed var(--border);
  display: none;
}
.card-detail.open { display: block; }
.detail-section { margin-top: 14px; }
.detail-section h4 { font-size: 13px; color: var(--text-secondary); margin-bottom: 6px; text-transform: uppercase; letter-spacing: 0.5px; }
.detail-section .content { background: #f8fafc; border-radius: var(--radius-sm); padding: 12px; font-size: 14px; line-height: 1.7; }
.detail-section .answer { color: var(--success); font-weight: 700; }

/* ===== Scrollbar ===== */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: #cbd5e1; border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: #94a3b8; }

/* ===== Responsive ===== */
@media (max-width: 860px) {
  .sidebar { position: absolute; transform: translateX(-100%); transition: transform 0.3s ease; }
  .sidebar.open { transform: translateX(0); }
  .top-bar { padding: 12px 16px 8px; }
  .filter-bar { gap: 12px 16px; }
  .content-area { padding: 16px; }
}