/* ════════════════════════════════════════════════
   Exercises — Fill-in-the-Blank, True/False, Matching, Short Answer
   ════════════════════════════════════════════════ */

/* ── Exercise Card ── */
.exercises-card { position: relative; }

.ex-gen-row {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 16px;
    flex-wrap: wrap;
}

.ex-gen-btn {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    background: linear-gradient(135deg, #f59e0b, #d97706);
    border: none;
    color: white;
    padding: 9px 18px;
    border-radius: var(--radius-md);
    font-family: var(--font);
    font-size: 13px;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition);
    box-shadow: 0 4px 14px rgba(245, 158, 11, 0.3);
}
.ex-gen-btn:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: 0 8px 20px rgba(245, 158, 11, 0.4);
}
.ex-gen-btn:disabled { opacity: 0.6; cursor: not-allowed; transform: none; }
.ex-gen-btn svg { width: 14px; height: 14px; }

.ex-score-badge {
    font-size: 13px;
    font-weight: 700;
    color: white;
    background: linear-gradient(135deg, #f59e0b, #d97706);
    padding: 4px 12px;
    border-radius: 20px;
    margin-left: auto;
}

/* ── Tab Bar ── */
.ex-tab-bar {
    display: flex;
    gap: 4px;
    background: rgba(255, 255, 255, 0.04);
    border-radius: var(--radius-md);
    padding: 4px;
    margin-bottom: 16px;
    overflow-x: auto;
}

.ex-tab {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 8px 14px;
    background: transparent;
    border: none;
    color: var(--text-muted);
    font-family: var(--font);
    font-size: 12px;
    font-weight: 600;
    cursor: pointer;
    border-radius: 8px;
    transition: all var(--transition);
    white-space: nowrap;
}
.ex-tab:hover { color: var(--text-primary); background: rgba(255, 255, 255, 0.05); }
.ex-tab.active {
    color: #f59e0b;
    background: rgba(245, 158, 11, 0.12);
}
.ex-tab-icon { font-size: 14px; }
.ex-tab-count {
    font-size: 10px;
    background: rgba(255, 255, 255, 0.1);
    padding: 1px 6px;
    border-radius: 8px;
    min-width: 18px;
    text-align: center;
}
.ex-tab.active .ex-tab-count { background: rgba(245, 158, 11, 0.2); }

/* ── Section Header ── */
.ex-section-header {
    display: flex;
    align-items: center;
    gap: 8px;
    margin-bottom: 16px;
    flex-wrap: wrap;
}
.ex-section-icon { font-size: 20px; }
.ex-section-header h4 {
    font-size: 16px;
    font-weight: 700;
    margin: 0;
    color: var(--text-primary);
}
.ex-section-hint {
    font-size: 12px;
    color: var(--text-muted);
    margin-left: auto;
}

/* ── Exercise Item ── */
.ex-item {
    display: flex;
    gap: 14px;
    padding: 16px;
    border: 1.5px solid var(--border);
    border-radius: var(--radius-md);
    margin-bottom: 12px;
    transition: all 0.3s ease;
    animation: fadeInUp 0.3s ease both;
}
.ex-item:hover { border-color: rgba(245, 158, 11, 0.3); }
.ex-item.checked-correct { border-color: var(--success); background: rgba(16, 185, 129, 0.04); }
.ex-item.checked-wrong { border-color: var(--error); background: rgba(239, 68, 68, 0.04); }

.ex-item-num {
    width: 28px;
    height: 28px;
    flex-shrink: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(245, 158, 11, 0.1);
    color: #f59e0b;
    font-size: 12px;
    font-weight: 700;
    border-radius: 8px;
    font-family: var(--font-mono);
}
.ex-item-body { flex: 1; min-width: 0; }

/* ── Fill-in-the-Blank ── */
.ex-fb-sentence {
    font-size: 15px;
    line-height: 2;
    color: var(--text-primary);
    margin-bottom: 10px;
}

.ex-blank-input {
    display: inline-block;
    width: 140px;
    padding: 4px 10px;
    border: 2px dashed rgba(245, 158, 11, 0.4);
    border-radius: 6px;
    background: rgba(245, 158, 11, 0.06);
    color: var(--text-primary);
    font-family: var(--font);
    font-size: 14px;
    font-weight: 600;
    text-align: center;
    outline: none;
    transition: all var(--transition);
    vertical-align: middle;
}
.ex-blank-input:focus {
    border-color: #f59e0b;
    background: rgba(245, 158, 11, 0.1);
    box-shadow: 0 0 0 3px rgba(245, 158, 11, 0.15);
}
.ex-blank-input.correct {
    border-color: var(--success);
    background: rgba(16, 185, 129, 0.08);
    border-style: solid;
    color: var(--success);
}
.ex-blank-input.wrong {
    border-color: var(--error);
    background: rgba(239, 68, 68, 0.08);
    border-style: solid;
    color: var(--error);
    text-decoration: line-through;
}

/* ── Hint ── */
.ex-hint {
    font-size: 12px;
    color: var(--text-muted);
    background: rgba(139, 92, 246, 0.06);
    border-left: 3px solid rgba(139, 92, 246, 0.3);
    padding: 6px 12px;
    border-radius: 0 6px 6px 0;
    margin-bottom: 10px;
}

/* ── True/False ── */
.ex-tf-statement {
    font-size: 15px;
    line-height: 1.6;
    color: var(--text-primary);
    margin-bottom: 12px;
    font-weight: 500;
}

.ex-tf-buttons {
    display: flex;
    gap: 10px;
    margin-bottom: 10px;
}

.ex-tf-btn {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 12px 16px;
    border: 1.5px solid var(--border);
    border-radius: var(--radius-md);
    background: transparent;
    color: var(--text-primary);
    font-family: var(--font);
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition);
}

.ex-tf-icon { font-size: 16px; font-weight: 700; }

.ex-tf-true:hover:not(:disabled) {
    border-color: rgba(16, 185, 129, 0.5);
    background: rgba(16, 185, 129, 0.06);
}
.ex-tf-false:hover:not(:disabled) {
    border-color: rgba(239, 68, 68, 0.5);
    background: rgba(239, 68, 68, 0.06);
}
.ex-tf-btn.selected {
    border-color: var(--accent);
    background: rgba(139, 92, 246, 0.08);
}
.ex-tf-btn.correct {
    border-color: var(--success) !important;
    background: var(--success-bg) !important;
    color: var(--success);
}
.ex-tf-btn.wrong {
    border-color: var(--error) !important;
    background: var(--error-bg) !important;
    color: var(--error);
}
.ex-tf-btn.reveal-correct {
    border-color: var(--success) !important;
    background: var(--success-bg) !important;
}
.ex-tf-btn:disabled { cursor: not-allowed; opacity: 0.85; }

/* ── Matching ── */
.ex-match-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
    margin-bottom: 16px;
}

.ex-match-col {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.ex-match-card {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 12px 14px;
    border: 1.5px solid var(--border);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition);
    font-size: 13px;
    color: var(--text-primary);
    line-height: 1.5;
    position: relative;
}

.ex-match-card:hover { border-color: rgba(245, 158, 11, 0.4); }
.ex-match-card.selected {
    border-color: #f59e0b;
    background: rgba(245, 158, 11, 0.08);
    box-shadow: 0 0 0 2px rgba(245, 158, 11, 0.2);
}
.ex-match-card.matched {
    border-color: var(--accent);
    background: rgba(139, 92, 246, 0.06);
}
.ex-match-card.correct {
    border-color: var(--success) !important;
    background: rgba(16, 185, 129, 0.06) !important;
}
.ex-match-card.wrong {
    border-color: var(--error) !important;
    background: rgba(239, 68, 68, 0.06) !important;
}

.ex-match-letter, .ex-match-num {
    width: 24px;
    height: 24px;
    flex-shrink: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 6px;
    font-size: 11px;
    font-weight: 700;
    font-family: var(--font-mono);
}
.ex-match-letter {
    background: rgba(245, 158, 11, 0.15);
    color: #f59e0b;
}
.ex-match-num {
    background: rgba(139, 92, 246, 0.15);
    color: var(--accent-light);
}

.ex-match-linked {
    margin-left: auto;
    font-size: 11px;
    font-weight: 700;
    color: var(--accent-light);
    flex-shrink: 0;
}

.ex-match-actions {
    display: flex;
    align-items: center;
    gap: 10px;
    flex-wrap: wrap;
}

.ex-match-result {
    display: flex;
    align-items: center;
    gap: 12px;
    flex-wrap: wrap;
}
.ex-match-score {
    font-size: 15px;
    font-weight: 700;
    color: var(--accent-light);
}

/* ── Short Answer ── */
.ex-sa-question {
    font-size: 15px;
    font-weight: 600;
    line-height: 1.55;
    color: var(--text-primary);
    margin-bottom: 10px;
}

.ex-sa-textarea {
    width: 100%;
    min-height: 80px;
    padding: 12px;
    border: 1.5px solid var(--border);
    border-radius: var(--radius-md);
    background: rgba(255, 255, 255, 0.02);
    color: var(--text-primary);
    font-family: var(--font);
    font-size: 13px;
    line-height: 1.6;
    resize: vertical;
    outline: none;
    transition: border-color var(--transition);
    margin-bottom: 10px;
    box-sizing: border-box;
}
.ex-sa-textarea:focus {
    border-color: var(--accent);
    box-shadow: 0 0 0 3px rgba(139, 92, 246, 0.15);
}
.ex-sa-textarea:disabled {
    opacity: 0.7;
    background: rgba(255, 255, 255, 0.01);
}

.ex-sa-model-answer {
    background: rgba(139, 92, 246, 0.06);
    border: 1px solid rgba(139, 92, 246, 0.2);
    border-radius: var(--radius-md);
    padding: 14px;
    margin-bottom: 12px;
    animation: fadeInUp 0.3s ease both;
}
.ex-sa-label {
    font-size: 12px;
    font-weight: 700;
    color: var(--accent-light);
    margin-bottom: 6px;
}
.ex-sa-answer-text {
    font-size: 14px;
    line-height: 1.6;
    color: var(--text-primary);
}
.ex-sa-keypoints {
    margin-top: 10px;
    padding-top: 10px;
    border-top: 1px solid rgba(139, 92, 246, 0.15);
    font-size: 12px;
    color: var(--text-secondary);
}
.ex-sa-keypoints strong { color: var(--text-primary); font-size: 11px; text-transform: uppercase; letter-spacing: 0.3px; }
.ex-sa-keypoints ul { margin: 6px 0 0 16px; padding: 0; }
.ex-sa-keypoints li { margin-bottom: 3px; }

/* Self-assessment */
.ex-sa-self-assess {
    display: flex;
    align-items: center;
    gap: 8px;
    flex-wrap: wrap;
}
.ex-sa-assess-label {
    font-size: 12px;
    font-weight: 600;
    color: var(--text-muted);
}
.ex-sa-assess-btn {
    padding: 6px 14px;
    border: 1.5px solid var(--border);
    border-radius: 20px;
    background: transparent;
    color: var(--text-secondary);
    font-family: var(--font);
    font-size: 12px;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition);
}
.ex-sa-assess-btn:hover { border-color: rgba(245, 158, 11, 0.4); }
.ex-sa-assess-btn.active {
    border-color: #f59e0b;
    background: rgba(245, 158, 11, 0.12);
    color: #f59e0b;
}

/* ── Feedback ── */
.ex-feedback {
    font-size: 13px;
    padding: 10px 14px;
    border-radius: 8px;
    margin-top: 8px;
    line-height: 1.5;
    animation: fadeInUp 0.3s ease both;
}
.ex-feedback.correct {
    background: rgba(16, 185, 129, 0.08);
    border-left: 3px solid var(--success);
    color: var(--success);
}
.ex-feedback.wrong {
    background: rgba(239, 68, 68, 0.08);
    border-left: 3px solid var(--error);
    color: var(--text-primary);
}
.ex-fb-explain {
    margin-top: 6px;
    font-size: 12px;
    color: var(--text-secondary);
}

/* ── Buttons ── */
.ex-check-btn {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 8px 18px;
    background: linear-gradient(135deg, var(--accent), var(--accent-dark));
    border: none;
    color: white;
    border-radius: var(--radius-md);
    font-family: var(--font);
    font-size: 13px;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition);
    margin-top: 4px;
}
.ex-check-btn:hover:not(:disabled) { transform: translateY(-1px); box-shadow: 0 4px 12px rgba(109, 40, 217, 0.35); }
.ex-check-btn:disabled { opacity: 0.4; cursor: not-allowed; transform: none; }

.ex-reset-btn {
    padding: 8px 18px;
    background: transparent;
    border: 1px solid var(--border);
    color: var(--text-muted);
    border-radius: var(--radius-md);
    font-family: var(--font);
    font-size: 13px;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition);
}
.ex-reset-btn:hover { border-color: var(--text-secondary); color: var(--text-primary); }

.ex-reveal-btn { background: linear-gradient(135deg, #6366f1, #4f46e5); }

/* ── Loading & Empty ── */
.ex-loading {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 40px 20px;
    gap: 16px;
    color: var(--text-muted);
}
.ex-loading-spinner {
    width: 36px; height: 36px;
    border: 3px solid rgba(245, 158, 11, 0.15);
    border-top-color: #f59e0b;
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }

.ex-empty {
    text-align: center;
    padding: 40px 20px;
    color: var(--text-muted);
    font-size: 14px;
}

.ex-error {
    text-align: center;
    padding: 30px 20px;
    color: var(--text-muted);
}
.ex-retry-btn {
    margin-top: 12px;
    padding: 8px 20px;
    background: var(--accent);
    border: none;
    color: white;
    border-radius: var(--radius-md);
    font-family: var(--font);
    font-size: 13px;
    font-weight: 600;
    cursor: pointer;
}

/* ── Responsive ── */
@media (max-width: 600px) {
    .ex-match-container {
        grid-template-columns: 1fr;
    }
    .ex-tab-bar {
        overflow-x: auto;
        -webkit-overflow-scrolling: touch;
    }
    .ex-tab { padding: 6px 10px; font-size: 11px; }
    .ex-tf-buttons { flex-direction: column; }
    .ex-sa-self-assess { flex-direction: column; align-items: flex-start; }
}

/* ── Light Mode ── */
.light-mode .ex-blank-input {
    background: rgba(245, 158, 11, 0.04);
}
.light-mode .ex-tab.active {
    background: rgba(245, 158, 11, 0.08);
}
.light-mode .ex-match-card:hover {
    background: rgba(245, 158, 11, 0.03);
}
.light-mode .ex-sa-textarea {
    background: rgba(0, 0, 0, 0.01);
}
.light-mode .ex-sa-model-answer {
    background: rgba(139, 92, 246, 0.04);
}
.light-mode .ex-feedback.correct { color: #047857; }