/* ========================================
   Lesson Player Styles
   ======================================== */

/* Layout */
.lesson-layout {
    display: flex;
    min-height: 100vh;
    padding-top: var(--nav-height);
}

/* Sidebar */
.lesson-sidebar {
    width: var(--sidebar-width);
    background: var(--bg-sidebar);
    border-right: 1px solid var(--border-color);
    position: fixed;
    top: var(--nav-height);
    left: 0;
    bottom: 0;
    overflow-y: auto;
    z-index: 100;
    transition: transform var(--transition-normal);
}

.lesson-sidebar-header {
    padding: 20px;
    border-bottom: 1px solid var(--border-color);
}

.lesson-sidebar-title {
    font-size: 1rem;
    margin-bottom: 12px;
}

.lesson-sidebar-title a {
    color: var(--text-white);
}

.lesson-sidebar-title a:hover {
    color: var(--primary);
}

.lesson-sidebar-progress {
    margin-bottom: 8px;
}

.lesson-sidebar-progress-text {
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-bottom: 8px;
}

/* Module Accordion */
.module-accordion {
    padding: 0;
}

.module-item {
    border-bottom: 1px solid var(--border-color);
}

.module-header {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 16px 20px;
    cursor: pointer;
    transition: background var(--transition-fast);
}

.module-header:hover {
    background: var(--bg-card);
}

.module-icon {
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--primary-glow);
    border-radius: 8px;
    color: var(--primary);
    flex-shrink: 0;
}

.module-icon svg {
    width: 18px;
    height: 18px;
}

.module-info {
    flex: 1;
}

.module-title {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-white);
    margin-bottom: 2px;
}

.module-meta {
    font-size: 0.75rem;
    color: var(--text-dim);
}

.module-toggle {
    color: var(--text-dim);
    transition: transform var(--transition-fast);
}

.module-toggle svg {
    width: 16px;
    height: 16px;
}

.module-item.active .module-toggle {
    transform: rotate(180deg);
}

.module-lessons {
    display: none;
    background: var(--bg-dark);
}

.module-item.active .module-lessons {
    display: block;
}

/* Lesson List */
.lesson-list-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px 20px 12px 36px;
    color: var(--text-muted);
    font-size: 0.85rem;
    transition: all var(--transition-fast);
    border-left: 3px solid transparent;
}

.lesson-list-item:hover {
    background: var(--bg-card);
    color: var(--text-light);
}

.lesson-list-item.current {
    background: var(--primary-glow);
    color: var(--primary);
    border-left-color: var(--primary);
}

.lesson-list-item.completed {
    color: var(--success);
}

.lesson-list-item.locked {
    opacity: 0.5;
}

.lesson-status-icon {
    width: 20px;
    height: 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.lesson-status-icon svg {
    width: 16px;
    height: 16px;
}

.lesson-list-title {
    flex: 1;
}

.lesson-list-meta {
    font-size: 0.75rem;
    color: var(--text-dim);
}

/* Main Content */
.lesson-main {
    flex: 1;
    margin-left: var(--sidebar-width);
    padding: 40px;
    max-width: 900px;
}

.lesson-header {
    margin-bottom: 40px;
}

.lesson-meta {
    display: flex;
    align-items: center;
    gap: 16px;
    margin-bottom: 16px;
    font-size: 0.875rem;
    color: var(--text-muted);
}

.lesson-meta span {
    display: flex;
    align-items: center;
    gap: 6px;
}

.lesson-meta svg {
    width: 16px;
    height: 16px;
}

.lesson-title {
    font-size: 2rem;
    margin-bottom: 8px;
}

/* Content Sections */
.lesson-content {
    color: var(--text-light);
    line-height: 1.8;
}

.lesson-section {
    margin-bottom: 48px;
}

/* Hero Section */
.section-hero {
    text-align: center;
    padding: 40px;
    background: linear-gradient(135deg, var(--primary-glow), transparent);
    border-radius: 12px;
    margin-bottom: 32px;
}

.section-hero h2 {
    font-size: 1.75rem;
    margin-bottom: 8px;
}

.section-hero p {
    color: var(--text-muted);
    margin: 0;
}

/* Text Section */
.section-text p {
    margin-bottom: 1.5rem;
}

.section-text ul, .section-text ol {
    margin: 1rem 0 1.5rem 1.5rem;
}

.section-text li {
    margin-bottom: 0.5rem;
}

/* Definition Box */
.section-definition {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-left: 4px solid var(--primary);
    border-radius: 8px;
    padding: 24px;
}

.section-definition .def-header {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 16px;
}

.section-definition .def-title {
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--primary);
}

.section-definition .def-term {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-white);
    margin-bottom: 8px;
}

.section-definition .def-formula {
    font-family: var(--font-mono);
    font-size: 1.25rem;
    color: var(--primary);
    background: var(--bg-dark);
    padding: 12px 20px;
    border-radius: 6px;
    display: inline-block;
    margin: 12px 0;
}

.section-definition .def-meaning {
    color: var(--text-light);
    margin-bottom: 16px;
}

.section-definition .def-variables {
    font-size: 0.9rem;
}

.section-definition .def-variables dt {
    color: var(--primary);
    font-family: var(--font-mono);
    display: inline;
}

.section-definition .def-variables dd {
    color: var(--text-muted);
    display: inline;
    margin: 0 0 8px 8px;
}

/* Analogy Box */
.section-analogy {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 24px;
}

.section-analogy .analogy-header {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 16px;
}

.section-analogy .analogy-icon {
    width: 40px;
    height: 40px;
    background: var(--secondary-glow);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
}

.section-analogy .analogy-title {
    font-size: 1.1rem;
    font-weight: 600;
}

/* Callout Box */
.section-callout {
    border-radius: 8px;
    padding: 20px 24px;
    display: flex;
    gap: 16px;
}

.section-callout.style-important {
    background: rgba(255, 82, 82, 0.1);
    border: 1px solid rgba(255, 82, 82, 0.3);
}

.section-callout.style-tip {
    background: rgba(0, 212, 255, 0.1);
    border: 1px solid rgba(0, 212, 255, 0.3);
}

.section-callout.style-warning {
    background: rgba(255, 193, 7, 0.1);
    border: 1px solid rgba(255, 193, 7, 0.3);
}

.section-callout .callout-icon {
    font-size: 1.5rem;
    flex-shrink: 0;
}

.section-callout .callout-title {
    font-weight: 600;
    margin-bottom: 8px;
}

/* Example Box */
.section-example {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    overflow: hidden;
}

.section-example .example-header {
    padding: 16px 24px;
    background: var(--bg-dark);
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.section-example .example-title {
    font-size: 1rem;
    font-weight: 600;
}

.section-example .example-difficulty {
    font-size: 0.75rem;
    padding: 4px 8px;
    border-radius: 4px;
}

.section-example .example-difficulty.easy {
    background: var(--success-glow);
    color: var(--success);
}

.section-example .example-difficulty.medium {
    background: rgba(255, 193, 7, 0.2);
    color: #ffc107;
}

.section-example .example-difficulty.hard {
    background: rgba(255, 82, 82, 0.2);
    color: #ff5252;
}

.section-example .example-problem {
    padding: 20px 24px;
    font-family: var(--font-mono);
    font-size: 1.1rem;
    color: var(--primary);
    border-bottom: 1px solid var(--border-color);
}

.section-example .example-steps {
    padding: 24px;
}

.section-example .step {
    display: flex;
    gap: 16px;
    margin-bottom: 24px;
}

.section-example .step:last-child {
    margin-bottom: 0;
}

.section-example .step-number {
    width: 28px;
    height: 28px;
    background: var(--primary);
    color: var(--bg-dark);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 0.85rem;
    flex-shrink: 0;
}

.section-example .step-content {
    flex: 1;
}

.section-example .step-title {
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--text-white);
}

.section-example .step-text {
    color: var(--text-muted);
    white-space: pre-wrap;
}

.section-example .example-answer {
    padding: 16px 24px;
    background: var(--success-glow);
    border-top: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    gap: 12px;
}

.section-example .answer-label {
    font-weight: 600;
    color: var(--success);
}

.section-example .answer-value {
    font-family: var(--font-mono);
    font-size: 1.25rem;
    color: var(--text-white);
}

.section-example .example-insight {
    padding: 16px 24px;
    background: var(--bg-dark);
    font-size: 0.9rem;
    color: var(--text-muted);
    border-top: 1px solid var(--border-color);
}

/* Illustration */
.section-illustration {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 24px;
    text-align: center;
}

.section-illustration .illustration-title {
    font-size: 1rem;
    margin-bottom: 8px;
}

.section-illustration .illustration-desc {
    font-size: 0.9rem;
    color: var(--text-muted);
    margin-bottom: 20px;
}

.section-illustration .illustration-container {
    background: var(--bg-dark);
    border-radius: 8px;
    padding: 40px;
    min-height: 200px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.section-illustration svg {
    max-width: 100%;
    height: auto;
}

/* Image Sections (JPG/PNG real-world images) */
.section-image {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 24px;
    text-align: center;
}

.section-image .image-title {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--text-primary);
}

.section-image .image-desc {
    font-size: 0.9rem;
    color: var(--text-muted);
    margin-bottom: 20px;
}

.section-image .image-container {
    background: var(--bg-dark);
    border-radius: 8px;
    overflow: hidden;
}

.section-image .lesson-image {
    width: 100%;
    max-width: 640px;
    height: auto;
    display: block;
    margin: 0 auto;
}

/* Practice Questions */
.section-practice {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    overflow: hidden;
}

.section-practice .practice-header {
    padding: 16px 24px;
    background: var(--bg-dark);
    border-bottom: 1px solid var(--border-color);
}

.section-practice .practice-title {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 4px;
}

.section-practice .practice-desc {
    font-size: 0.85rem;
    color: var(--text-muted);
    margin: 0;
}

.practice-question {
    padding: 24px;
    border-bottom: 1px solid var(--border-color);
}

.practice-question:last-child {
    border-bottom: none;
}

.practice-question-text {
    font-size: 1rem;
    margin-bottom: 16px;
    color: var(--text-white);
}

.practice-options {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.practice-option {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px 16px;
    background: var(--bg-dark);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.practice-option:hover {
    border-color: var(--primary);
}

.practice-option.selected {
    border-color: var(--primary);
    background: var(--primary-glow);
}

.practice-option.correct {
    border-color: var(--success);
    background: var(--success-glow);
}

.practice-option.incorrect {
    border-color: var(--error);
    background: rgba(255, 82, 82, 0.1);
}

.practice-option-radio {
    width: 20px;
    height: 20px;
    border: 2px solid var(--border-light);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.practice-option.selected .practice-option-radio {
    border-color: var(--primary);
    background: var(--primary);
}

.practice-option.selected .practice-option-radio::after {
    content: '';
    width: 8px;
    height: 8px;
    background: var(--bg-dark);
    border-radius: 50%;
}

.practice-feedback {
    margin-top: 16px;
    padding: 16px;
    border-radius: 8px;
    display: none;
}

.practice-feedback.show {
    display: block;
}

.practice-feedback.correct {
    background: var(--success-glow);
    border: 1px solid var(--success);
}

.practice-feedback.incorrect {
    background: rgba(255, 82, 82, 0.1);
    border: 1px solid var(--error);
}

/* Summary Box */
.section-summary {
    background: var(--bg-card);
    border: 2px solid var(--primary);
    border-radius: 12px;
    padding: 24px;
}

.section-summary .summary-title {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 16px;
    color: var(--primary);
}

.section-summary ul {
    list-style: none;
    margin: 0;
    padding: 0;
}

.section-summary li {
    position: relative;
    padding-left: 24px;
    margin-bottom: 12px;
    color: var(--text-light);
}

.section-summary li::before {
    content: '';
    position: absolute;
    left: 0;
    top: 8px;
    width: 8px;
    height: 8px;
    background: var(--primary);
    border-radius: 50%;
}

/* Next Lesson */
.section-next-lesson {
    background: linear-gradient(135deg, var(--primary-glow), transparent);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 24px;
    text-align: center;
}

.section-next-lesson p {
    margin-bottom: 20px;
    color: var(--text-muted);
}

.section-next-lesson .next-lesson-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
}

/* Lesson Navigation */
.lesson-navigation {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 48px;
    padding-top: 32px;
    border-top: 1px solid var(--border-color);
    gap: 16px;
}

.lesson-nav-btn {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 16px 24px;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    color: var(--text-light);
    transition: all var(--transition-fast);
}

.lesson-nav-btn:hover {
    border-color: var(--primary);
    color: var(--primary);
}

.lesson-nav-btn svg {
    width: 20px;
    height: 20px;
}

.lesson-nav-btn.prev {
    flex-direction: row;
}

.lesson-nav-btn.next {
    flex-direction: row-reverse;
}

.lesson-nav-text {
    text-align: left;
}

.lesson-nav-btn.next .lesson-nav-text {
    text-align: right;
}

.lesson-nav-label {
    font-size: 0.75rem;
    color: var(--text-dim);
    display: block;
    margin-bottom: 2px;
}

.lesson-nav-title {
    font-weight: 600;
}

.mark-complete-btn {
    padding: 16px 32px;
}

/* Mobile Sidebar Toggle */
.sidebar-toggle {
    display: none;
    position: fixed;
    bottom: 20px;
    left: 20px;
    width: 56px;
    height: 56px;
    background: var(--primary);
    color: var(--bg-dark);
    border: none;
    border-radius: 50%;
    cursor: pointer;
    z-index: 200;
    box-shadow: var(--shadow-lg);
}

.sidebar-toggle svg {
    width: 24px;
    height: 24px;
}

/* Responsive */
@media (max-width: 992px) {
    .lesson-sidebar {
        transform: translateX(-100%);
    }

    .lesson-sidebar.open {
        transform: translateX(0);
    }

    .lesson-main {
        margin-left: 0;
        padding: 24px;
    }

    .sidebar-toggle {
        display: flex;
        align-items: center;
        justify-content: center;
    }

    .lesson-navigation {
        flex-direction: column;
    }

    .lesson-nav-btn {
        width: 100%;
        justify-content: center;
    }
}

@media (max-width: 768px) {
    .lesson-title {
        font-size: 1.5rem;
    }

    .section-hero {
        padding: 24px;
    }

    .section-example .example-steps {
        padding: 16px;
    }

    .section-example .step {
        flex-direction: column;
        gap: 8px;
    }
}