/* ============================================
   Exercise System Styles
   ============================================ */

/* Hide static lesson exercises - replaced by interactive system */
.lesson-exercise {
    display: none;
}

.exercise-section {
    margin-top: 3rem;
    padding-top: 2rem;
    border-top: 2px solid var(--border-light, #e5e7eb);
}

.exercise-section-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 1.5rem;
    flex-wrap: wrap;
    gap: 1rem;
}

.exercise-section-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-dark, #1f2937);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.exercise-section-title i {
    color: var(--primary, #3b82f6);
}

.exercise-progress-badge {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.4rem 1rem;
    background: var(--bg-light, #f3f4f6);
    border-radius: 2rem;
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-light, #6b7280);
}

.exercise-progress-badge .score {
    color: var(--primary, #3b82f6);
}

/* Individual Exercise Card */
.exercise-card {
    background: var(--bg-white, #ffffff);
    border: 1px solid var(--border-light, #e5e7eb);
    border-radius: 12px;
    padding: 1.5rem;
    margin-bottom: 1.5rem;
    transition: border-color 0.3s ease, box-shadow 0.3s ease;
}

.exercise-card:hover {
    border-color: var(--primary-light, #93c5fd);
}

.exercise-card.completed {
    border-color: #10b981;
    background: #f0fdf4;
}

.exercise-card.completed.incorrect {
    border-color: #ef4444;
    background: #fef2f2;
}

.exercise-card-header {
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    margin-bottom: 1rem;
    gap: 0.75rem;
}

.exercise-number {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 28px;
    height: 28px;
    min-width: 28px;
    background: var(--primary, #3b82f6);
    color: white;
    border-radius: 50%;
    font-size: 0.8rem;
    font-weight: 700;
}

.exercise-card.completed .exercise-number {
    background: #10b981;
}

.exercise-card.completed.incorrect .exercise-number {
    background: #ef4444;
}

.exercise-badges {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.exercise-type-badge,
.exercise-difficulty-badge {
    padding: 0.2rem 0.6rem;
    border-radius: 1rem;
    font-size: 0.7rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.exercise-type-badge {
    background: #eff6ff;
    color: #3b82f6;
}

.exercise-difficulty-badge.easy {
    background: #f0fdf4;
    color: #16a34a;
}

.exercise-difficulty-badge.medium {
    background: #fffbeb;
    color: #d97706;
}

.exercise-difficulty-badge.hard {
    background: #fef2f2;
    color: #dc2626;
}

/* Question */
.exercise-question {
    font-size: 1.05rem;
    font-weight: 600;
    color: var(--text-dark, #1f2937);
    margin-bottom: 1.25rem;
    line-height: 1.6;
}

.exercise-question code {
    background: #f1f5f9;
    padding: 0.15rem 0.4rem;
    border-radius: 4px;
    font-family: 'Fira Code', 'Courier New', monospace;
    font-size: 0.9em;
    color: #e11d48;
}

/* MCQ / True-False Options */
.exercise-options {
    display: flex;
    flex-direction: column;
    gap: 0.6rem;
    margin-bottom: 1rem;
}

.exercise-option {
    display: flex;
    align-items: flex-start;
    gap: 0.75rem;
    padding: 0.75rem 1rem;
    border: 2px solid var(--border-light, #e5e7eb);
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.2s ease;
    background: var(--bg-white, #ffffff);
}

.exercise-option:hover:not(.disabled) {
    border-color: var(--primary, #3b82f6);
    background: #eff6ff;
}

.exercise-option.selected {
    border-color: var(--primary, #3b82f6);
    background: #eff6ff;
}

.exercise-option.correct {
    border-color: #10b981;
    background: #f0fdf4;
}

.exercise-option.incorrect {
    border-color: #ef4444;
    background: #fef2f2;
}

.exercise-option.disabled {
    cursor: default;
    opacity: 0.85;
}

.exercise-option-key {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 28px;
    height: 28px;
    min-width: 28px;
    border: 2px solid var(--border-light, #e5e7eb);
    border-radius: 50%;
    font-size: 0.8rem;
    font-weight: 700;
    color: var(--text-light, #6b7280);
    transition: all 0.2s ease;
}

.exercise-option.selected .exercise-option-key {
    background: var(--primary, #3b82f6);
    border-color: var(--primary, #3b82f6);
    color: white;
}

.exercise-option.correct .exercise-option-key {
    background: #10b981;
    border-color: #10b981;
    color: white;
}

.exercise-option.incorrect .exercise-option-key {
    background: #ef4444;
    border-color: #ef4444;
    color: white;
}

.exercise-option-text {
    flex: 1;
    line-height: 1.5;
    padding-top: 0.15rem;
}

/* Multi-select checkbox style */
.exercise-option.multi-select .exercise-option-key {
    border-radius: 4px;
}

/* Code Input */
.exercise-code-input {
    width: 100%;
    min-height: 100px;
    padding: 1rem;
    font-family: 'Fira Code', 'Courier New', monospace;
    font-size: 0.9rem;
    line-height: 1.6;
    background: #1e293b;
    color: #e2e8f0;
    border: 2px solid #334155;
    border-radius: 8px;
    resize: vertical;
    margin-bottom: 1rem;
    tab-size: 4;
}

.exercise-code-input:focus {
    outline: none;
    border-color: var(--primary, #3b82f6);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.15);
}

.exercise-code-input:disabled {
    opacity: 0.7;
    cursor: not-allowed;
}

.exercise-code-input::placeholder {
    color: #64748b;
}

/* Short Answer Input */
.exercise-text-input {
    width: 100%;
    padding: 0.75rem 1rem;
    font-size: 1rem;
    border: 2px solid var(--border-light, #e5e7eb);
    border-radius: 8px;
    margin-bottom: 1rem;
    transition: border-color 0.2s ease;
}

.exercise-text-input:focus {
    outline: none;
    border-color: var(--primary, #3b82f6);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

.exercise-text-input:disabled {
    opacity: 0.7;
    cursor: not-allowed;
    background: var(--bg-light, #f3f4f6);
}

/* Code Ordering - Sortable */
.exercise-ordering-list {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    margin-bottom: 1rem;
}

.exercise-ordering-item {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.75rem 1rem;
    background: #1e293b;
    color: #e2e8f0;
    border: 2px solid #334155;
    border-radius: 8px;
    cursor: grab;
    font-family: 'Fira Code', 'Courier New', monospace;
    font-size: 0.85rem;
    user-select: none;
    transition: all 0.2s ease;
}

.exercise-ordering-item:active {
    cursor: grabbing;
}

.exercise-ordering-item:hover {
    border-color: var(--primary, #3b82f6);
}

.exercise-ordering-item.dragging {
    opacity: 0.5;
    border-color: var(--primary, #3b82f6);
}

.exercise-ordering-item .drag-handle {
    color: #64748b;
    font-size: 1rem;
}

.exercise-ordering-item .order-number {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 24px;
    height: 24px;
    min-width: 24px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 4px;
    font-size: 0.75rem;
    font-weight: 700;
}

.exercise-ordering-item.disabled {
    cursor: default;
}

.exercise-ordering-item.correct-position {
    border-color: #10b981;
    background: #064e3b;
}

.exercise-ordering-item.incorrect-position {
    border-color: #ef4444;
    background: #450a0a;
}

/* Matching */
.exercise-matching-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
    margin-bottom: 1rem;
}

.exercise-matching-left,
.exercise-matching-right {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.exercise-matching-item {
    padding: 0.6rem 1rem;
    border: 2px solid var(--border-light, #e5e7eb);
    border-radius: 8px;
    font-size: 0.9rem;
    background: var(--bg-white, #ffffff);
}

.exercise-matching-left .exercise-matching-item {
    font-weight: 600;
}

.exercise-matching-select {
    width: 100%;
    padding: 0.6rem 0.75rem;
    border: 2px solid var(--border-light, #e5e7eb);
    border-radius: 8px;
    font-size: 0.9rem;
    background: var(--bg-white, #ffffff);
    cursor: pointer;
}

.exercise-matching-select:focus {
    outline: none;
    border-color: var(--primary, #3b82f6);
}

.exercise-matching-select:disabled {
    cursor: not-allowed;
    opacity: 0.7;
}

/* Submit Button */
.exercise-submit-btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.7rem 1.5rem;
    background: var(--primary, #3b82f6);
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
}

.exercise-submit-btn:hover:not(:disabled) {
    background: #2563eb;
    transform: translateY(-1px);
}

.exercise-submit-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
}

.exercise-submit-btn.loading {
    pointer-events: none;
}

.exercise-submit-btn.loading i {
    animation: spin 1s linear infinite;
}

@keyframes spin {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}

.exercise-retry-btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.7rem 1.5rem;
    background: transparent;
    color: var(--primary, #3b82f6);
    border: 2px solid var(--primary, #3b82f6);
    border-radius: 8px;
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
    margin-left: 0.5rem;
}

.exercise-retry-btn:hover {
    background: #eff6ff;
}

/* Feedback / Explanation */
.exercise-feedback {
    margin-top: 1rem;
    padding: 1rem 1.25rem;
    border-radius: 8px;
    font-size: 0.95rem;
    line-height: 1.6;
    display: none;
}

.exercise-feedback.show {
    display: block;
    animation: fadeIn 0.3s ease;
}

.exercise-feedback.correct {
    background: #f0fdf4;
    border: 1px solid #86efac;
    color: #166534;
}

.exercise-feedback.incorrect {
    background: #fef2f2;
    border: 1px solid #fca5a5;
    color: #991b1b;
}

.exercise-feedback-icon {
    font-weight: 700;
    margin-right: 0.5rem;
}

.exercise-feedback .exercise-explanation {
    margin-top: 0.75rem;
    padding-top: 0.75rem;
    border-top: 1px solid rgba(0, 0, 0, 0.1);
    font-size: 0.9rem;
}

.exercise-model-answer {
    margin-top: 0.75rem;
    padding: 0.75rem;
    background: rgba(0, 0, 0, 0.05);
    border-radius: 6px;
    font-family: 'Fira Code', 'Courier New', monospace;
    font-size: 0.85rem;
    white-space: pre-wrap;
    overflow-x: auto;
}

/* Loading State */
.exercise-loading {
    text-align: center;
    padding: 2rem;
    color: var(--text-light, #6b7280);
}

.exercise-loading i {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
    animation: spin 1s linear infinite;
}

.exercise-empty {
    text-align: center;
    padding: 2rem;
    color: var(--text-light, #6b7280);
    font-style: italic;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(-5px); }
    to { opacity: 1; transform: translateY(0); }
}

/* RTL Support */
[dir="rtl"] .exercise-card-header {
    flex-direction: row-reverse;
}

[dir="rtl"] .exercise-option {
    flex-direction: row-reverse;
}

[dir="rtl"] .exercise-feedback-icon {
    margin-right: 0;
    margin-left: 0.5rem;
}

[dir="rtl"] .exercise-retry-btn {
    margin-left: 0;
    margin-right: 0.5rem;
}

[dir="rtl"] .exercise-ordering-item {
    flex-direction: row-reverse;
}

[dir="rtl"] .exercise-matching-container {
    direction: rtl;
}

/* Responsive */
@media (max-width: 768px) {
    .exercise-section-header {
        flex-direction: column;
        align-items: flex-start;
    }

    .exercise-matching-container {
        grid-template-columns: 1fr;
    }

    .exercise-code-input {
        min-height: 80px;
        font-size: 0.8rem;
    }

    .exercise-card {
        padding: 1rem;
    }
}