```css
/* ============================================================
   CUSTOM STYLES FOR C TUTORIALS
   ============================================================ */

/* ========== TYPOGRAPHY - ENHANCED & READABLE ========== */
.title-main {
    font-size: 38px;
    line-height: 1.3;
    color: #0066cc;
    border-left: 5px solid #0066cc;
    padding-left: 18px;
    margin-top: 0;
}

.section-title {
    font-size: 32px;
    line-height: 1.3;
    margin-top: 30px;
    color: #1a1a1a;
    border-bottom: 2px solid #e0e0e0;
    padding-bottom: 8px;
}

.sub-title {
    font-size: 26px;
    line-height: 1.4;
    margin-top: 25px;
    color: #0066cc;
}

.sub-title-small {
    font-size: 22px;
    line-height: 1.4;
    margin-top: 20px;
    color: #0066cc;
}

.content-text {
    font-size: 19px;
    line-height: 1.9;
    margin-bottom: 22px;
    color: #1a1a1a;
}

p {
    font-size: 19px;
    line-height: 1.9;
    color: #1a1a1a;
}

/* ========== TABLE OF CONTENTS - VERTICAL (Learn Box Style) ========== */
.toc-box {
    background: linear-gradient(135deg, #e8f4f8, #dcecf2);
    border-left: 6px solid #0066cc;
    padding: 24px 28px;
    margin: 28px 0;
    border-radius: 12px;
    box-shadow: 0 4px 12px rgba(0, 102, 204, 0.06);
}

.toc-title {
    font-family: 'Merriweather', 'Georgia', serif;
    font-size: 22px;
    font-weight: 700;
    color: #004d99;
    display: block;
    margin-bottom: 12px;
    letter-spacing: -0.01em;
}

.toc-list {
    margin: 0;
    padding: 0;
    list-style: none;
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    font-size: 17px;
    line-height: 1.8;
    color: #1a2a3a;
}

.toc-list li {
    margin: 6px 0;
    padding-left: 28px;
    position: relative;
}

.toc-list li::before {
    content: '▸';
    position: absolute;
    left: 0;
    top: 0;
    color: #0066cc;
    font-size: 18px;
    font-weight: 700;
}

.toc-list li::after {
    display: none;
}

.toc-list a {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    font-size: 17px;
    font-weight: 500;
    color: #0066cc;
    text-decoration: none;
    padding: 2px 0;
    transition: all 0.2s ease;
    border-bottom: 2px solid transparent;
    display: inline-block;
}

.toc-list a:hover {
    color: #004d99;
    border-bottom-color: #0066cc;
    text-decoration: none;
}

/* ========== LEARN BOX - ENHANCED ========== */
.learn-box {
    background: linear-gradient(135deg, #e8f4f8, #dcecf2);
    border-left: 6px solid #0066cc;
    padding: 24px 28px;
    margin: 28px 0;
    border-radius: 12px;
    box-shadow: 0 4px 12px rgba(0, 102, 204, 0.06);
}

.learn-title {
    font-family: 'Merriweather', 'Georgia', serif;
    font-size: 22px;
    font-weight: 700;
    color: #004d99;
    display: block;
    margin-bottom: 12px;
    letter-spacing: -0.01em;
}

.learn-list {
    margin: 0;
    padding: 0;
    list-style: none;
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    font-size: 18px;
    line-height: 1.8;
    color: #1a2a3a;
}

.learn-list li {
    margin: 6px 0;
    padding-left: 28px;
    position: relative;
}

.learn-list li::before {
    content: '✅';
    position: absolute;
    left: 0;
    top: 0;
    font-size: 18px;
}

.learn-list li code {
    font-family: 'JetBrains Mono', 'Courier New', monospace;
    font-size: 0.95em;
    background: rgba(0, 102, 204, 0.08);
    color: #0066cc;
    padding: 2px 8px;
    border-radius: 4px;
}

/* ========== ADVANTAGES BOX ========== */
.advantages-box {
    background: #e8f4f8;
    padding: 20px 25px;
    border-radius: 10px;
    margin: 20px 0;
}

.advantages-box p {
    font-size: 19px;
    margin: 10px 0;
}

/* ========== FILE MODES BOX ========== */
.file-modes-box {
    background: #f5f5f5;
    padding: 20px;
    border-radius: 8px;
    margin: 20px 0;
    font-family: 'JetBrains Mono', monospace;
    font-size: 17px;
}

.file-modes-box p {
    font-size: 17px;
    margin: 8px 0;
}

/* ========== PARAMETERS BOX ========== */
.parameters-box {
    background: #f9f9f9;
    padding: 15px 20px;
    border-radius: 8px;
    margin: 15px 0;
}

.parameters-box p {
    font-size: 19px;
    margin: 8px 0;
}

/* ========== CODE BLOCKS - LARGER & READABLE ========== */
.code-container {
    background: #1e1e2e;
    border-radius: 12px;
    padding: 0;
    overflow-x: auto;
    margin: 24px 0;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
}

.code-block {
    background: #1e1e2e;
    border: none;
    margin: 0;
    padding: 24px 28px;
    font-size: 17px;
    line-height: 1.8;
    font-family: 'JetBrains Mono', 'Courier New', Consolas, monospace;
    color: #cdd6f4;
    overflow-x: auto;
}

.code-block code {
    background: transparent;
    color: #cdd6f4;
    padding: 0;
    font-size: 17px;
    line-height: 1.8;
}

/* ========== INLINE CODE ========== */
code {
    font-family: 'JetBrains Mono', 'Courier New', monospace;
    font-size: 0.95em;
    background: #f0f4f8;
    color: #0066cc;
    padding: 3px 10px;
    border-radius: 6px;
    font-weight: 500;
}

/* ========== LISTS ========== */
.content-list {
    font-size: 19px;
    line-height: 1.9;
    margin: 15px 0 20px 25px;
}

.content-list li {
    margin: 10px 0;
}

/* ========== IMAGES ========== */
.image-wrapper {
    text-align: center;
}

.image-container {
    text-align: center;
}

.responsive-img {
    max-width: 100%;
    height: auto;
    border-radius: 8px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
}

/* ========== DIVIDER ========== */
.divider {
    border: none;
    height: 1px;
    background: linear-gradient(to right, #ddd, transparent);
    margin: 30px 0;
}

/* ========== RELATED ARTICLES ========== */
.related-box {
    margin: 30px 0;
    padding: 20px;
    background: #f9f9f9;
    border-radius: 8px;
}

.related-title {
    margin-top: 0;
    font-size: 24px;
}

.related-list {
    margin: 10px 0 0 20px;
}

.related-list li {
    margin: 8px 0;
}

.related-list a {
    font-size: 17px;
    color: #0066cc;
    text-decoration: none;
}

.related-list a:hover {
    text-decoration: underline;
}

/* ========== NAVIGATION LINKS ========== */
.nav-links {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Arial, sans-serif;
    font-size: 18px;
    color: #333;
    padding: 12px 20px;
    border: 1px solid #ccc;
    border-radius: 10px;
    display: inline-block;
    background-color: transparent;
    font-weight: 500;
    margin: 20px 0;
}

.nav-link {
    font-size: 17px;
    color: #0066cc;
    background-color: rgba(0, 102, 204, 0.1);
    padding: 8px 16px;
    border-radius: 8px;
    text-decoration: none;
    margin-right: 8px;
    transition: all 0.2s ease;
    font-weight: 500;
}

.nav-link:hover {
    background-color: rgba(0, 102, 204, 0.2);
    text-decoration: underline;
}

/* ============================================================
   OTHER TOPICS - ENHANCED VISUAL DESIGN
   ============================================================ */

.other-topics {
    border: 1px solid #e0e8f0;
    padding: 30px 32px;
    border-radius: 16px;
    margin: 35px 0;
    background: linear-gradient(145deg, #f8fafc, #f0f4f8);
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.04);
}

.other-topics-title {
    font-family: 'Merriweather', 'Georgia', serif;
    font-size: 28px;
    font-weight: 700;
    color: #1a1a1a;
    margin: 0 0 24px 0;
    padding-bottom: 14px;
    border-bottom: 3px solid #0066cc;
    letter-spacing: -0.02em;
    position: relative;
}

.other-topics-title:after {
    content: '';
    position: absolute;
    bottom: -3px;
    left: 0;
    width: 60px;
    height: 3px;
    background: #0066cc;
    border-radius: 2px;
}

.topic-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 20px;
}

.topic-category {
    background: #ffffff;
    padding: 18px 20px 20px 20px;
    border-radius: 12px;
    border: 1px solid #e8edf3;
    transition: all 0.3s ease;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.02);
}

.topic-category:hover {
    border-color: #0066cc;
    box-shadow: 0 4px 16px rgba(0, 102, 204, 0.08);
    transform: translateY(-2px);
}

.category-title {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    font-size: 16px;
    font-weight: 700;
    color: #0066cc;
    margin: 0 0 12px 0;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.topic-links {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.topic-links a {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    font-size: 15px;
    font-weight: 500;
    color: #1a2a3a;
    text-decoration: none;
    padding: 6px 14px;
    background: #f0f5fa;
    border-radius: 20px;
    border: 1px solid transparent;
    transition: all 0.25s ease;
    display: inline-block;
    line-height: 1.4;
}

.topic-links a:hover {
    background: #0066cc;
    color: #fff;
    border-color: #0066cc;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 102, 204, 0.25);
}

.topic-links a:visited {
    color: #6c5b7b;
}

.topic-links a:visited:hover {
    color: #fff;
}

/* ============================================================
   SIDEBAR FIX - WITH MOBILE TOGGLE (COMPLETE)
   ============================================================ */

/* Desktop: Make sidebar scroll with page */
@media screen and (min-width: 1281px) {
    #sidebar {
        position: relative !important;
        height: auto !important;
        top: auto !important;
        left: auto !important;
        overflow: visible !important;
        box-shadow: none !important;
        width: 26em !important;
        flex-shrink: 0 !important;
        margin-left: 0 !important;
        background: #f5f6f7 !important;
    }

    #sidebar > .inner {
        position: relative !important;
        height: auto !important;
        overflow: visible !important;
        padding: 2.22222em 2.22222em 2.44444em 2.22222em !important;
        width: 26em !important;
    }

    #sidebar .toggle {
        display: none !important;
    }

    #wrapper {
        display: flex !important;
        flex-direction: row-reverse !important;
        min-height: 100vh !important;
    }

    #main {
        flex-grow: 1 !important;
        width: 100% !important;
        float: none !important;
    }

    #sidebar > .inner::-webkit-scrollbar {
        display: none !important;
    }
    #sidebar > .inner {
        -ms-overflow-style: none !important;
        scrollbar-width: none !important;
    }
}

/* Tablet & Mobile: Fixed sidebar with toggle button */
@media screen and (max-width: 1280px) {
    /* Toggle button - always visible on tablet/mobile */
    #sidebar .toggle {
        display: block !important;
        position: fixed !important;
        top: 20px !important;
        left: 20px !important;
        z-index: 10001 !important;
        width: 50px !important;
        height: 50px !important;
        background: #f56a6a !important;
        border-radius: 8px !important;
        color: #fff !important;
        text-indent: -9999px !important;
        cursor: pointer !important;
        box-shadow: 0 2px 10px rgba(0, 0, 0, 0.2) !important;
        transition: all 0.3s ease !important;
    }

    #sidebar .toggle:before {
        content: '\f0c9' !important;
        font-family: 'Font Awesome 5 Free' !important;
        font-weight: 900 !important;
        font-size: 24px !important;
        color: #fff !important;
        text-indent: 0 !important;
        position: absolute !important;
        top: 50% !important;
        left: 50% !important;
        transform: translate(-50%, -50%) !important;
    }

    /* Sidebar fixed on tablet/mobile */
    #sidebar {
        position: fixed !important;
        height: 100% !important;
        top: 0 !important;
        left: 0 !important;
        z-index: 10000 !important;
        width: 24em !important;
        background: #f5f6f7 !important;
        box-shadow: 0 0 5em 0 rgba(0, 0, 0, 0.175) !important;
        overflow-y: auto !important;
        transition: margin-left 0.3s ease !important;
    }
    
    #sidebar.inactive {
        margin-left: -24em !important;
    }

    /* When sidebar is open, toggle stays at same position */
    #sidebar:not(.inactive) .toggle {
        left: 20px !important;
        background: #f56a6a !important;
    }

    #sidebar:not(.inactive) .toggle:before {
        content: '\f0c9' !important;
    }
}

/* Small mobile screens */
@media screen and (max-width: 480px) {
    #sidebar {
        width: 20em !important;
    }
    
    #sidebar.inactive {
        margin-left: -20em !important;
    }
    
    #sidebar .toggle {
        top: 15px !important;
        left: 15px !important;
        width: 44px !important;
        height: 44px !important;
    }

    #sidebar .toggle:before {
        font-size: 20px !important;
    }
    
    #sidebar:not(.inactive) .toggle {
        left: 15px !important;
    }
}

/* ========== RESPONSIVE DESIGN ========== */
@media (max-width: 768px) {
    .title-main {
        font-size: 28px;
    }
    .section-title {
        font-size: 24px;
    }
    .sub-title {
        font-size: 22px;
    }
    .content-text {
        font-size: 17px;
    }
    p {
        font-size: 17px;
    }
    .code-block {
        font-size: 15px;
        padding: 16px 18px;
    }
    .code-block code {
        font-size: 15px;
    }
    .learn-box {
        padding: 18px 20px;
    }
    .learn-list {
        font-size: 16px;
    }
    .learn-title {
        font-size: 20px;
    }
    .toc-title {
        font-size: 20px;
    }
    .toc-list a {
        font-size: 16px;
    }
    .file-modes-box {
        font-size: 16px;
        padding: 15px;
    }
    .file-modes-box p {
        font-size: 16px;
    }
    .parameters-box p {
        font-size: 17px;
    }
    .content-list {
        font-size: 17px;
    }
    .nav-links {
        font-size: 16px;
        padding: 10px 16px;
    }
    .nav-link {
        font-size: 16px;
    }
    .other-topics {
        padding: 18px;
    }
    .other-topics-title {
        font-size: 24px;
    }
    .topic-grid {
        grid-template-columns: 1fr;
    }
    .topic-links a {
        font-size: 14px;
        padding: 3px 8px;
    }
    .related-list a {
        font-size: 16px;
    }
    .related-title {
        font-size: 22px;
    }
}

@media (max-width: 480px) {
    .title-main {
        font-size: 24px;
    }
    .section-title {
        font-size: 22px;
    }
    .content-text {
        font-size: 16px;
    }
    p {
        font-size: 16px;
    }
    .learn-box {
        padding: 14px 16px;
    }
    .learn-list {
        font-size: 15px;
        margin-left: 0;
    }
    .learn-list li {
        padding-left: 22px;
    }
    .learn-title {
        font-size: 18px;
    }
    .toc-list {
        flex-direction: column;
        gap: 4px;
    }
    .toc-list li::after {
        display: none;
    }
    .toc-list a {
        font-size: 15px;
    }
    .code-block {
        font-size: 14px;
        padding: 12px 14px;
    }
    .code-block code {
        font-size: 14px;
    }
    .file-modes-box {
        font-size: 15px;
        padding: 12px;
    }
    .file-modes-box p {
        font-size: 15px;
    }
    .parameters-box p {
        font-size: 16px;
    }
    .content-list {
        font-size: 16px;
    }
    .nav-links {
        font-size: 15px;
        padding: 8px 12px;
    }
    .nav-link {
        font-size: 15px;
    }
    .other-topics {
        padding: 14px;
    }
    .other-topics-title {
        font-size: 20px;
    }
    .topic-links a {
        font-size: 13px;
        padding: 2px 6px;
    }
    .related-list a {
        font-size: 15px;
    }
    .related-title {
        font-size: 20px;
    }
}
```