/* Question Bank Styles */
#questionBankSection {
    padding: 2rem 0;
}

.qb-unit-tabs {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
    margin-bottom: 1.5rem;
    padding: 0.5rem;
    background: rgba(255,255,255,0.7);
    border-radius: 12px;
    backdrop-filter: blur(8px);
}
.qb-unit-tab {
    padding: 0.7rem 1.4rem;
    border: 2px solid #16a34a;
    background: white;
    color: #16a34a;
    border-radius: 8px;
    cursor: pointer;
    font-weight: 600;
    font-size: 0.95rem;
    transition: all 0.3s;
    display: flex; align-items: center; gap: 0.4rem;
}
.qb-unit-tab:hover { background: #f0fdf4; transform: translateY(-2px); }
.qb-unit-tab.active {
    background: linear-gradient(135deg, #16a34a 0%, #15803d 100%);
    color: white; border-color: #15803d;
    box-shadow: 0 4px 12px rgba(22,163,74,0.3);
}
.qb-unit-header {
    background: linear-gradient(135deg, #16a34a 0%, #166534 100%);
    color: white; padding: 1.5rem 2rem;
    border-radius: 12px 12px 0 0;
    margin-bottom: 0;
}
.qb-unit-header h3 { font-size: 1.4rem; margin: 0 0 0.5rem; }
.qb-subtitle { opacity: 0.9; font-size: 0.9rem; margin: 0; }
.qb-questions-list {
    background: white;
    border-radius: 0 0 12px 12px;
    box-shadow: 0 4px 16px rgba(0,0,0,0.08);
    overflow: hidden;
}
.qb-question-card {
    border-bottom: 1px solid #e5e7eb;
    transition: box-shadow 0.3s;
}
.qb-question-card:last-child { border-bottom: none; }
.qb-question-card:hover { box-shadow: inset 4px 0 0 #16a34a; }
.qb-question-header {
    display: flex; align-items: flex-start; gap: 1rem;
    padding: 1.2rem 1.5rem; cursor: pointer;
    transition: background 0.2s;
}
.qb-question-header:hover { background: #f0fdf4; }
.qb-q-number {
    background: linear-gradient(135deg, #16a34a 0%, #15803d 100%);
    color: white; font-weight: 700; font-size: 0.85rem;
    min-width: 42px; height: 42px;
    border-radius: 50%; display: flex;
    align-items: center; justify-content: center;
    flex-shrink: 0;
}
.qb-q-content { flex: 1; }
.qb-topic-badge { margin-bottom: 0.5rem; }
.qb-topic-link {
    display: inline-flex; align-items: center; gap: 0.3rem;
    padding: 0.2rem 0.7rem; border-radius: 20px;
    font-size: 0.78rem; font-weight: 600;
    background: #dcfce7; color: #166534;
    text-decoration: none; transition: all 0.2s;
}
.qb-topic-link:hover { background: #16a34a; color: white; }
.qb-question-text {
    font-size: 0.95rem; color: #374151;
    line-height: 1.6; margin: 0 0 0.5rem 0;
}
.qb-marks-total {
    font-size: 0.82rem; font-weight: 600;
    color: #d97706; display: flex; align-items: center; gap: 0.3rem;
}
.qb-expand-icon {
    color: #9ca3af; font-size: 1.1rem;
    padding-top: 0.3rem; transition: transform 0.3s;
}
.qb-answer-section {
    padding: 0 1.5rem 1.5rem 1.5rem;
    background: #f8fafc;
    border-top: 2px dashed #e5e7eb;
    animation: slideDown 0.3s ease;
}
@keyframes slideDown {
    from { opacity: 0; max-height: 0; }
    to   { opacity: 1; max-height: 5000px; }
}
.qb-scheme-section { margin-bottom: 1.5rem; padding-top: 1rem; }
.qb-scheme-section h4, .qb-solution-section h4 {
    color: #166534; font-size: 1.05rem;
    margin: 0 0 0.8rem; display: flex;
    align-items: center; gap: 0.5rem;
}
.qb-scheme-grid {
    display: grid; gap: 0.5rem;
}
.qb-scheme-item {
    display: flex; align-items: center; gap: 0.7rem;
    padding: 0.6rem 1rem; background: white;
    border-radius: 8px; border-left: 4px solid #16a34a;
    font-size: 0.88rem; color: #374151;
}
.qb-marks-badge {
    background: #16a34a; color: white;
    padding: 0.15rem 0.5rem; border-radius: 4px;
    font-weight: 700; font-size: 0.78rem;
    min-width: 30px; text-align: center;
}
.qb-solution-content {
    background: white; padding: 1.5rem;
    border-radius: 10px;
    border: 1px solid #e5e7eb;
    font-size: 0.92rem; line-height: 1.7;
    color: #1f2937;
}
.qb-solution-content h4 {
    color: #166534; margin: 1.2rem 0 0.5rem;
    padding-bottom: 0.3rem;
    border-bottom: 2px solid #dcfce7;
}
.qb-solution-content h4:first-child { margin-top: 0; }
.qb-solution-content table.hot-table {
    width: 100%; border-collapse: collapse;
    margin: 0.8rem 0; font-size: 0.85rem;
}
.qb-solution-content table.hot-table th {
    background: #166534; color: white;
    padding: 0.5rem 0.8rem; text-align: left;
}
.qb-solution-content table.hot-table td {
    padding: 0.5rem 0.8rem;
    border-bottom: 1px solid #e5e7eb;
}
.qb-solution-content table.hot-table tr:nth-child(even) {
    background: #f0fdf4;
}
.qb-solution-content pre {
    background: #1e293b; color: #e2e8f0;
    padding: 1rem; border-radius: 8px;
    overflow-x: auto; font-size: 0.82rem;
    margin: 0.8rem 0;
}
.qb-solution-content code {
    font-family: 'Consolas', 'Monaco', monospace;
}
.qb-solution-content ul, .qb-solution-content ol {
    padding-left: 1.5rem; margin: 0.5rem 0;
}
.qb-solution-content li { margin-bottom: 0.3rem; }

/* Back button for QB section */
.qb-back-btn {
    display: inline-flex; align-items: center; gap: 0.5rem;
    padding: 0.6rem 1.2rem; border-radius: 8px;
    background: linear-gradient(135deg, #16a34a 0%, #15803d 100%);
    color: white; border: none; cursor: pointer;
    font-weight: 600; font-size: 0.95rem;
    margin-bottom: 1.5rem; transition: all 0.3s;
}
.qb-back-btn:hover { transform: translateY(-2px); box-shadow: 0 4px 12px rgba(22,163,74,0.3); }

@media (max-width: 768px) {
    .qb-unit-tabs { flex-direction: column; }
    .qb-question-header { flex-direction: column; }
    .qb-q-number { align-self: flex-start; }
    .qb-solution-content { padding: 1rem; }
}