/* ============================================
   FlowChart Academy - Lesson Styles
   ============================================ */

/* --- Lesson Page Layout --- */
.lesson-page {
    display: flex;
    max-width: var(--max-width);
    margin: 0 auto;
    min-height: calc(100vh - var(--nav-height) - 80px);
}

/* --- Sidebar --- */
.lesson-sidebar {
    width: var(--sidebar-width);
    flex-shrink: 0;
    padding: var(--space-xl) var(--space-lg);
    border-right: 1px solid var(--color-border);
    background: var(--color-surface);
    position: sticky;
    top: var(--nav-height);
    height: calc(100vh - var(--nav-height));
    overflow-y: auto;
}

.lesson-sidebar h3 {
    font-size: var(--font-size-sm);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--color-text-light);
    margin-bottom: var(--space-md);
}

.lesson-list {
    list-style: none;
    counter-reset: lesson-counter;
}

.lesson-list li {
    counter-increment: lesson-counter;
}

.lesson-list li a {
    display: block;
    padding: var(--space-sm) var(--space-sm) var(--space-sm) var(--space-lg);
    margin-bottom: 2px;
    border-radius: var(--border-radius);
    color: var(--color-text-light);
    font-size: var(--font-size-sm);
    position: relative;
    transition: all var(--transition-fast);
}

.lesson-list li a::before {
    content: counter(lesson-counter) ".";
    position: absolute;
    left: var(--space-sm);
    color: var(--color-text-lighter);
    font-weight: 600;
    font-size: var(--font-size-sm);
}

.lesson-list li a:hover {
    background: var(--color-primary-light);
    color: var(--color-primary);
}

.lesson-list li.current a {
    background: var(--color-primary-light);
    color: var(--color-primary);
    font-weight: 600;
}

.lesson-list li.current a::before {
    color: var(--color-primary);
}

/* --- Main Content --- */
.lesson-main {
    flex: 1;
    min-width: 0;
    padding: var(--space-xl) var(--space-2xl);
}

.lesson-header {
    margin-bottom: var(--space-2xl);
}

.lesson-number {
    display: inline-block;
    font-size: var(--font-size-sm);
    color: var(--color-primary);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: var(--space-sm);
}

.lesson-header h1 {
    color: var(--color-text);
}

/* --- Lesson Content Sections --- */
.lesson-body h2 {
    margin-top: var(--space-2xl);
    margin-bottom: var(--space-md);
    padding-bottom: var(--space-sm);
    border-bottom: 2px solid var(--color-border);
}

.lesson-body p {
    margin-bottom: var(--space-md);
    line-height: 1.7;
}

.lesson-body ul,
.lesson-body ol {
    margin-bottom: var(--space-md);
    padding-left: var(--space-xl);
}

.lesson-body li {
    margin-bottom: var(--space-xs);
    line-height: 1.6;
}

/* --- Concept Callout --- */
.concept-callout {
    background: var(--color-primary-light);
    border-left: 4px solid var(--color-primary);
    padding: var(--space-md) var(--space-lg);
    border-radius: 0 var(--border-radius) var(--border-radius) 0;
    margin: var(--space-lg) 0;
}

.concept-callout p:last-child {
    margin-bottom: 0;
}

/* --- Shape Reference Cards --- */
.shape-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--space-lg);
    margin: var(--space-lg) 0;
}

.shape-card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius-lg);
    padding: var(--space-lg);
    text-align: center;
    transition: box-shadow var(--transition-fast);
}

.shape-card:hover {
    box-shadow: var(--shadow-md);
}

.shape-card svg {
    margin: 0 auto var(--space-md);
    width: 100px;
    height: 60px;
}

.shape-card h4 {
    font-size: var(--font-size-base);
    margin-bottom: var(--space-xs);
}

.shape-card p {
    font-size: var(--font-size-sm);
    color: var(--color-text-light);
    margin-bottom: 0;
}

/* --- Interactive Flowchart Area --- */
.flowchart-container {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius-lg);
    padding: var(--space-lg);
    margin: var(--space-lg) 0;
    box-shadow: var(--shadow-sm);
}

.flowchart-container svg {
    display: block;
    margin: 0 auto;
    max-width: 100%;
    max-height: 420px;
    width: auto;
}

/* --- Step-Through Controls --- */
.step-controls {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-sm);
    padding: var(--space-md);
    background: var(--color-bg);
    border-top: 1px solid var(--color-border);
    border-radius: 0 0 var(--border-radius-lg) var(--border-radius-lg);
    margin: 0 calc(-1 * var(--space-lg)) calc(-1 * var(--space-lg));
}

.step-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: var(--space-sm) var(--space-md);
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    cursor: pointer;
    font-size: var(--font-size-sm);
    font-weight: 500;
    color: var(--color-text);
    transition: all var(--transition-fast);
    min-width: 36px;
    height: 36px;
}

.step-btn:hover:not(:disabled) {
    background: var(--color-primary);
    color: white;
    border-color: var(--color-primary);
}

.step-btn:disabled {
    opacity: 0.4;
    cursor: not-allowed;
}

.step-btn.active {
    background: var(--color-primary);
    color: white;
    border-color: var(--color-primary);
}

.step-counter {
    font-size: var(--font-size-sm);
    color: var(--color-text-light);
    font-weight: 500;
    min-width: 80px;
    text-align: center;
}

/* --- Side-by-Side Layout (Flowchart + Pseudocode) --- */
.side-by-side {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--space-lg);
    margin: var(--space-lg) 0;
}

.side-by-side .flowchart-container,
.side-by-side .pseudocode-panel {
    margin: 0;
}

/* --- Pseudocode Panel --- */
.pseudocode-panel {
    background: #1e293b;
    border-radius: var(--border-radius-lg);
    padding: var(--space-lg);
    overflow-x: auto;
}

.pseudocode-panel pre {
    margin: 0;
    font-family: var(--font-mono);
    font-size: var(--font-size-sm);
    line-height: 1.8;
}

.pseudocode-panel .code-line {
    display: block;
    padding: 2px var(--space-sm);
    border-left: 3px solid transparent;
    color: #cbd5e1;
    transition: all var(--transition-base);
    border-radius: 0 4px 4px 0;
}

.pseudocode-panel .code-line.code-active {
    background: rgba(37, 99, 235, 0.2);
    border-left-color: var(--color-primary);
    color: #f1f5f9;
}

.pseudocode-panel .code-line.code-visited {
    opacity: 0.5;
}

/* Keywords in pseudocode */
.pseudocode-panel .kw {
    color: #c084fc;
    font-weight: 600;
}

.pseudocode-panel .str {
    color: #86efac;
}

.pseudocode-panel .num {
    color: #fbbf24;
}

.pseudocode-panel .comment {
    color: #64748b;
    font-style: italic;
}

/* --- Variable Watch Panel --- */
.var-watch {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    padding: var(--space-md);
    margin-top: var(--space-md);
}

.var-watch h4 {
    font-size: var(--font-size-sm);
    color: var(--color-text-light);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: var(--space-sm);
}

.var-watch table {
    width: 100%;
    border-collapse: collapse;
    font-family: var(--font-mono);
    font-size: var(--font-size-sm);
}

.var-watch th,
.var-watch td {
    padding: var(--space-xs) var(--space-sm);
    text-align: left;
    border-bottom: 1px solid var(--color-border);
}

.var-watch th {
    color: var(--color-text-light);
    font-weight: 500;
}

.var-watch td.changed {
    color: var(--color-primary);
    font-weight: 600;
    background: var(--color-primary-light);
}

/* --- Key Takeaways --- */
.takeaways {
    background: #f0fdf4;
    border: 1px solid #bbf7d0;
    border-radius: var(--border-radius-lg);
    padding: var(--space-lg);
    margin: var(--space-2xl) 0;
}

.takeaways h2 {
    font-size: var(--font-size-lg);
    color: var(--color-success);
    margin: 0 0 var(--space-md);
    padding: 0;
    border: none;
}

.takeaways ul {
    margin: 0;
    padding-left: var(--space-xl);
}

.takeaways li {
    margin-bottom: var(--space-sm);
}

/* --- Lesson Navigation --- */
.lesson-nav {
    display: flex;
    justify-content: space-between;
    margin-top: var(--space-3xl);
    padding-top: var(--space-xl);
    border-top: 1px solid var(--color-border);
}

.lesson-nav-btn {
    display: flex;
    flex-direction: column;
    padding: var(--space-md) var(--space-lg);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    transition: all var(--transition-fast);
    max-width: 45%;
}

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

.lesson-nav-btn .nav-direction {
    font-size: var(--font-size-sm);
    color: var(--color-text-light);
}

.lesson-nav-btn .nav-title {
    font-weight: 600;
    color: var(--color-text);
}

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

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

/* --- Responsive --- */
@media (max-width: 900px) {
    .side-by-side {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    .lesson-page {
        flex-direction: column;
    }

    .lesson-sidebar {
        width: 100%;
        position: static;
        height: auto;
        border-right: none;
        border-bottom: 1px solid var(--color-border);
        padding: var(--space-md);
    }

    .lesson-list {
        display: flex;
        flex-wrap: wrap;
        gap: var(--space-xs);
    }

    .lesson-list li a {
        padding: var(--space-xs) var(--space-sm) var(--space-xs) var(--space-lg);
        font-size: 0.8rem;
    }

    .lesson-main {
        padding: var(--space-lg);
    }

    .lesson-nav {
        flex-direction: column;
        gap: var(--space-md);
    }

    .lesson-nav-btn {
        max-width: 100%;
    }

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