/* ============================================
   CSS Architecture: Component-Based Design
   ============================================
   This stylesheet is organized into:
   1. CSS Variables (Design Tokens)
   2. Base/Reset Styles
   3. Layout Components
   4. Section Components
   5. Utility Classes
   6. Responsive Design
   ============================================ */

/* ============================================
   1. CSS Variables (Design Tokens)
   ============================================ */
:root {
    /* Colors */
    --color-primary: #667eea;
    --color-primary-dark: #5568d3;
    --color-secondary: #764ba2;
    --color-accent: #f093fb;
    --color-text: #2d3748;
    --color-text-light: #4a5568;
    --color-text-lighter: #718096;
    --color-background: #ffffff;
    --color-background-alt: #f7fafc;
    --color-border: #e2e8f0;
    --color-border-light: #f1f5f9;
    
    /* Typography */
    --font-family-primary: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    --font-size-base: 16px;
    --font-size-small: 14px;
    --font-size-large: 18px;
    --font-size-xl: 24px;
    --font-size-2xl: 32px;
    --font-size-3xl: 48px;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-2xl: 4rem;
    
    /* Layout */
    --container-max-width: 1200px;
    --border-radius: 8px;
    --border-radius-lg: 12px;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.1);
    
    /* Transitions */
    --transition-fast: 0.15s ease;
    --transition-base: 0.3s ease;
}

/* Dark Mode Variables */
[data-theme="dark"] {
    --color-primary: #818cf8;
    --color-primary-dark: #6366f1;
    --color-secondary: #a78bfa;
    --color-accent: #c084fc;
    --color-text: #e2e8f0;
    --color-text-light: #cbd5e1;
    --color-text-lighter: #94a3b8;
    --color-background: #1e293b;
    --color-background-alt: #0f172a;
    --color-border: #334155;
    --color-border-light: #1e293b;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.4);
}

/* ============================================
   2. Base/Reset Styles
   ============================================ */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family-primary);
    font-size: var(--font-size-base);
    line-height: 1.6;
    color: var(--color-text);
    background-color: var(--color-background-alt);
    transition: background-color var(--transition-base), color var(--transition-base);
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

a {
    color: var(--color-primary);
    text-decoration: none;
    transition: color var(--transition-fast);
}

a:hover {
    color: var(--color-primary-dark);
}

ul {
    list-style-position: inside;
}

/* ============================================
   3. Layout Components
   ============================================ */
.container {
    max-width: var(--container-max-width);
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* Header - Compact Horizontal Design */
.header {
    background: var(--color-background);
    color: var(--color-text);
    padding: var(--spacing-sm) 0;
    margin-bottom: var(--spacing-md);
    border-bottom: 1px solid var(--color-border);
}

.header-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--spacing-md);
    flex-wrap: wrap;
}

.header-left {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    flex: 1;
    min-width: 0;
}

.photo-container {
    flex-shrink: 0;
}

.photo {
    width: 60px;
    height: 60px;
    border-radius: 50%;
    object-fit: cover;
    border: 2px solid var(--color-border);
}

.header-text {
    min-width: 0;
}

.name {
    font-size: var(--font-size-lg);
    font-weight: 500;
    margin: 0;
    letter-spacing: 0.5px;
    color: var(--color-text);
    line-height: 1.2;
}

.name-link {
    text-decoration: none;
    color: inherit;
}

.name-link:hover {
    color: var(--color-primary);
}

.title {
    font-size: var(--font-size-small);
    color: var(--color-text-light);
    margin: 0;
    line-height: 1.2;
}

.about-me {
    font-size: var(--font-size-small);
    color: var(--color-text-light);
    margin: var(--spacing-xs) 0 0 0;
    line-height: 1.5;
    max-width: 600px;
}

.header-right {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    flex-shrink: 0;
}

/* Navigation */
.main-nav {
    display: flex;
    gap: var(--spacing-md);
    align-items: center;
}

.nav-link {
    color: var(--color-text-light);
    font-size: var(--font-size-base);
    text-decoration: none;
    padding: var(--spacing-xs) 0;
    border-bottom: 2px solid transparent;
    transition: all var(--transition-fast);
    white-space: nowrap;
}

.nav-link:hover {
    color: var(--color-primary);
}

.nav-link.active {
    color: var(--color-primary);
    border-bottom-color: var(--color-primary);
}

/* CV Section Navigation - Vertical Sidebar */
.cv-nav {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.cv-nav-link {
    color: var(--color-text-lighter);
    font-size: var(--font-size-base);
    text-decoration: none;
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--border-radius);
    transition: all var(--transition-fast);
    display: block;
    border-left: 3px solid transparent;
}

.cv-nav-link:hover {
    color: var(--color-primary);
    background-color: var(--color-background-alt);
    border-left-color: var(--color-primary);
}

.cv-nav-link.active {
    color: var(--color-primary);
    background-color: var(--color-background-alt);
    border-left-color: var(--color-primary);
    font-weight: 500;
}

.cv-nav-link-external {
    /* External links (like Posts) don't get active state from scroll */
    margin-top: var(--spacing-sm);
    padding-top: var(--spacing-md);
    border-top: 1px solid var(--color-border);
}

.name-link {
    color: var(--color-text);
    text-decoration: none;
    transition: color var(--transition-fast);
}

.name-link:hover {
    color: var(--color-primary);
}

.photo-container a {
    display: block;
    transition: opacity var(--transition-fast);
}

.photo-container a:hover {
    opacity: 0.8;
}

.header-actions {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.theme-toggle {
    background: none;
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    padding: var(--spacing-xs);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-text-light);
    transition: all var(--transition-fast);
    width: 36px;
    height: 36px;
}

.theme-toggle:hover {
    background-color: var(--color-background-alt);
    border-color: var(--color-primary);
    color: var(--color-primary);
}

.theme-icon {
    width: 18px;
    height: 18px;
    transition: opacity var(--transition-fast), transform var(--transition-fast);
}

.theme-icon-light {
    display: block;
}

.theme-icon-dark {
    display: none;
}

[data-theme="dark"] .theme-icon-light {
    display: none;
}

[data-theme="dark"] .theme-icon-dark {
    display: block;
}

.contact-info {
    display: flex;
    gap: var(--spacing-xs);
    align-items: center;
}

.contact-item {
    display: flex;
    align-items: center;
    color: var(--color-text-light);
    transition: color var(--transition-fast);
    padding: var(--spacing-xs);
    border-radius: var(--border-radius);
}

.contact-item:hover {
    color: var(--color-primary);
    background-color: var(--color-background-alt);
}

.contact-icon {
    width: 18px;
    height: 18px;
    fill: currentColor;
    flex-shrink: 0;
    transition: transform var(--transition-fast);
}

.contact-item:hover .contact-icon {
    transform: scale(1.15);
}

/* Fixed Left Sidebar */
.cv-sidebar {
    position: fixed;
    left: 0;
    top: 0;
    bottom: 0;
    width: 200px;
    background-color: var(--color-background);
    border-right: 1px solid var(--color-border);
    padding: var(--spacing-lg) var(--spacing-md);
    z-index: 1000;
    overflow-y: auto;
    padding-top: 120px; /* Space for header */
    box-shadow: 2px 0 8px rgba(0, 0, 0, 0.05);
}

/* Mobile Menu Toggle Button */
.mobile-menu-toggle {
    display: none;
    position: fixed;
    top: var(--spacing-md);
    left: var(--spacing-md);
    z-index: 1001;
    background-color: var(--color-background);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    padding: var(--spacing-xs) var(--spacing-sm);
    cursor: pointer;
    flex-direction: column;
    gap: 4px;
    box-shadow: var(--shadow-sm);
}

.mobile-menu-toggle span {
    width: 20px;
    height: 2px;
    background-color: var(--color-text);
    transition: all var(--transition-fast);
}

.mobile-menu-toggle:hover {
    background-color: var(--color-background-alt);
}

/* Mobile Overlay */
.mobile-overlay {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: rgba(0, 0, 0, 0.5);
    z-index: 999;
    opacity: 0;
    transition: opacity var(--transition-base);
}

.mobile-overlay.active {
    display: block;
    opacity: 1;
}

[data-theme="dark"] .mobile-overlay {
    background-color: rgba(0, 0, 0, 0.7);
}

/* Main Content with Sidebar */
.main-content-with-sidebar {
    margin-left: 200px; /* Space for sidebar */
    padding-bottom: var(--spacing-2xl);
}

/* Main Content */
.main-content {
    padding-bottom: var(--spacing-2xl);
}

/* Footer */
.footer {
    background-color: var(--color-text);
    color: var(--color-background);
    text-align: center;
    padding: var(--spacing-lg) 0;
    margin-top: var(--spacing-2xl);
}

[data-theme="dark"] .footer {
    background-color: var(--color-background-alt);
    color: var(--color-text);
    border-top: 1px solid var(--color-border);
}

/* ============================================
   4. Section Components
   ============================================ */
.section {
    background-color: var(--color-background);
    border-radius: var(--border-radius);
    padding: var(--spacing-md);
    margin-bottom: var(--spacing-md);
    border: 1px solid var(--color-border-light);
    transition: background-color var(--transition-base), border-color var(--transition-base);
}

/* Side-by-side sections layout */
.sections-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-md);
}

.section-half {
    margin-bottom: 0;
}

@media (max-width: 968px) {
    .sections-row {
        grid-template-columns: 1fr;
    }
    
    .section-half {
        margin-bottom: var(--spacing-md);
    }
}

.section-title {
    font-size: var(--font-size-large);
    font-weight: 600;
    color: var(--color-text);
    margin-bottom: var(--spacing-md);
    padding-bottom: var(--spacing-xs);
    border-bottom: 1px solid var(--color-border-light);
}

/* Timeline (for Work Experience & Education) */
.timeline {
    position: relative;
    padding-left: var(--spacing-lg);
}

.timeline::before {
    content: '';
    position: absolute;
    left: 8px;
    top: 0;
    bottom: 0;
    width: 2px;
    background: var(--color-border);
}

.timeline-item {
    position: relative;
    margin-bottom: var(--spacing-md);
    padding-left: var(--spacing-lg);
}

.timeline-marker {
    position: absolute;
    left: -24px;
    top: 4px;
    width: 16px;
    height: 16px;
    border-radius: 50%;
    background: var(--color-primary);
    border: 3px solid var(--color-background);
    box-shadow: var(--shadow-sm);
}

.item-title {
    font-size: var(--font-size-large);
    font-weight: 600;
    color: var(--color-text);
    margin-bottom: var(--spacing-xs);
}

.item-organization {
    font-size: var(--font-size-large);
    color: var(--color-primary);
    font-weight: 500;
    margin-bottom: var(--spacing-xs);
}

.item-period {
    font-size: var(--font-size-small);
    color: var(--color-text-lighter);
    font-style: italic;
    margin-bottom: var(--spacing-sm);
}

.item-description {
    color: var(--color-text-light);
    line-height: 1.8;
}

.item-description li {
    margin-bottom: var(--spacing-xs);
}

/* Publications */
.publications-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

.publication-item {
    padding: var(--spacing-md);
    background-color: var(--color-background-alt);
    border-radius: var(--border-radius);
    border-left: 4px solid var(--color-primary);
}

.publication-title {
    font-size: var(--font-size-large);
    font-weight: 600;
    color: var(--color-text);
    margin-bottom: var(--spacing-xs);
}

.publication-authors {
    color: var(--color-text-light);
    margin-bottom: var(--spacing-xs);
}

.publication-venue {
    color: var(--color-text-lighter);
    font-style: italic;
    margin-bottom: var(--spacing-sm);
}

.publication-links {
    display: flex;
    gap: var(--spacing-sm);
    flex-wrap: wrap;
}

.link-button {
    display: inline-block;
    padding: var(--spacing-xs) var(--spacing-sm);
    background-color: var(--color-primary);
    color: white;
    border-radius: var(--border-radius);
    font-size: var(--font-size-small);
    transition: background-color var(--transition-fast);
}

.link-button:hover {
    background-color: var(--color-primary-dark);
    color: white;
}

/* Skills */
.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
}

.skill-category {
    padding: var(--spacing-md);
    background-color: var(--color-background-alt);
    border-radius: var(--border-radius);
}

.skill-category-title {
    font-size: var(--font-size-large);
    font-weight: 600;
    color: var(--color-primary);
    margin-bottom: var(--spacing-sm);
}

.skill-tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
}

.skill-tag {
    display: inline-block;
    padding: var(--spacing-xs) var(--spacing-sm);
    background-color: var(--color-primary);
    color: white;
    border-radius: var(--border-radius);
    font-size: var(--font-size-small);
    font-weight: 500;
}

/* Awards */
.awards-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

.award-item {
    display: flex;
    gap: var(--spacing-md);
    padding: var(--spacing-md);
    background-color: var(--color-background-alt);
    border-radius: var(--border-radius);
    align-items: flex-start;
}

.award-icon {
    font-size: var(--font-size-2xl);
    flex-shrink: 0;
}

.award-content {
    flex: 1;
}

.award-title {
    font-size: var(--font-size-large);
    font-weight: 600;
    color: var(--color-text);
    margin-bottom: var(--spacing-xs);
}

.award-organization {
    color: var(--color-primary);
    font-weight: 500;
    margin-bottom: var(--spacing-xs);
}

.award-year {
    font-size: var(--font-size-small);
    color: var(--color-text-lighter);
    font-style: italic;
    margin-bottom: var(--spacing-xs);
}

.award-description {
    color: var(--color-text-light);
    line-height: 1.8;
    margin-bottom: var(--spacing-xs);
}

.achievement-links {
    display: flex;
    gap: var(--spacing-sm);
    flex-wrap: wrap;
    margin-top: var(--spacing-sm);
}

/* Blog */
.blog-intro {
    color: var(--color-text-light);
    margin-bottom: var(--spacing-lg);
    font-size: var(--font-size-base);
}

.blog-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.blog-item {
    border: 1px solid var(--color-border-light);
    border-radius: var(--border-radius);
    overflow: hidden;
    transition: all var(--transition-base);
    background-color: var(--color-background);
}

.blog-item:hover {
    border-color: var(--color-primary);
    box-shadow: var(--shadow-sm);
    transform: translateY(-2px);
}

.blog-link {
    text-decoration: none;
    color: inherit;
    display: block;
}

.blog-content {
    display: flex;
    gap: var(--spacing-md);
    align-items: flex-start;
}

.blog-image-container {
    flex-shrink: 0;
    width: 200px;
    height: 150px;
    overflow: hidden;
    background-color: var(--color-background-alt);
    display: flex;
    align-items: center;
    justify-content: center;
}

.blog-image {
    width: 100%;
    height: 100%;
    object-fit: contain;
    transition: transform var(--transition-base);
}

.blog-item:hover .blog-image {
    transform: scale(1.05);
}

.blog-text {
    flex: 1;
    padding: var(--spacing-md);
}

.blog-title {
    font-size: var(--font-size-large);
    font-weight: 600;
    color: var(--color-text);
    margin-bottom: var(--spacing-xs);
    transition: color var(--transition-fast);
}

.blog-item:hover .blog-title {
    color: var(--color-primary);
}

.blog-excerpt {
    color: var(--color-text-light);
    line-height: 1.6;
    margin-bottom: var(--spacing-sm);
}

.blog-date {
    font-size: var(--font-size-small);
    color: var(--color-text-lighter);
    font-style: italic;
}

/* Blog item without image - add class "no-image" to blog-item if no image */
.blog-item.no-image .blog-text {
    padding: var(--spacing-lg);
}

/* Blog Preview Section (Homepage) */
.blog-preview-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-md);
}

.blog-preview-footer {
    text-align: center;
    margin-top: var(--spacing-lg);
    padding-top: var(--spacing-md);
    border-top: 1px solid var(--color-border);
}

.blog-view-all-link {
    color: var(--color-primary);
    text-decoration: none;
    font-size: var(--font-size-base);
    font-weight: 500;
    transition: all var(--transition-fast);
    display: inline-block;
}

.blog-view-all-link:hover {
    color: var(--color-primary-dark);
    transform: translateX(4px);
}

.blog-empty {
    text-align: center;
    color: var(--color-text-light);
    font-style: italic;
    padding: var(--spacing-xl);
}

/* Individual Blog Article */
.breadcrumb {
    margin-bottom: var(--spacing-md);
}

.breadcrumb-link {
    color: var(--color-text-light);
    text-decoration: none;
    font-size: var(--font-size-base);
    transition: color var(--transition-fast);
}

.breadcrumb-link:hover {
    color: var(--color-primary);
}

.blog-article {
    max-width: 800px;
    margin: 0 auto;
}

.article-header {
    margin-bottom: var(--spacing-lg);
    padding-bottom: var(--spacing-md);
    border-bottom: 1px solid var(--color-border);
}

.article-title {
    font-size: var(--font-size-2xl);
    font-weight: 600;
    color: var(--color-text);
    margin-bottom: var(--spacing-sm);
    line-height: 1.3;
}

.article-meta {
    font-size: var(--font-size-small);
    color: var(--color-text-lighter);
    font-style: italic;
}

.article-image-container {
    width: 100%;
    margin: var(--spacing-lg) 0;
    border-radius: var(--border-radius);
    overflow: hidden;
    background-color: var(--color-background-alt);
}

.article-image {
    width: 100%;
    height: auto;
    display: block;
}

.article-content {
    line-height: 1.8;
    color: var(--color-text);
}

.article-content h2 {
    font-size: var(--font-size-xl);
    font-weight: 600;
    color: var(--color-text);
    margin-top: var(--spacing-xl);
    margin-bottom: var(--spacing-md);
    padding-bottom: var(--spacing-xs);
    border-bottom: 1px solid var(--color-border-light);
}

.article-content h3 {
    font-size: var(--font-size-large);
    font-weight: 600;
    color: var(--color-text);
    margin-top: var(--spacing-lg);
    margin-bottom: var(--spacing-sm);
}

.article-content p {
    margin-bottom: var(--spacing-md);
    color: var(--color-text-light);
}

.article-content ul,
.article-content ol {
    margin-bottom: var(--spacing-md);
    padding-left: var(--spacing-lg);
    color: var(--color-text-light);
}

.article-content li {
    margin-bottom: var(--spacing-xs);
}

.article-content pre {
    background-color: var(--color-background-alt);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    padding: var(--spacing-md);
    overflow-x: auto;
    margin-bottom: var(--spacing-md);
}

.article-content code {
    font-family: 'Courier New', Courier, monospace;
    font-size: var(--font-size-small);
    color: var(--color-primary);
}

.article-content pre code {
    color: var(--color-text);
    display: block;
}

/* PDF Viewer Styles */
.article-content .pdf-container {
    width: 100%;
    height: 800px;
    margin: var(--spacing-xl) 0;
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    overflow: hidden;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    background-color: var(--color-background-alt);
}

.article-content .pdf-container iframe {
    width: 100%;
    height: 100%;
    border: none;
    display: block;
}

/* Responsive PDF viewer */
@media (max-width: 768px) {
    .article-content .pdf-container {
        height: 600px;
    }
}

@media (max-width: 480px) {
    .article-content .pdf-container {
        height: 500px;
    }
}

/* ============================================
   5. Responsive Design
   ============================================ */
@media (max-width: 768px) {
    :root {
        --font-size-3xl: 36px;
        --font-size-2xl: 28px;
        --spacing-2xl: 3rem;
        --spacing-xl: 2rem;
    }
    
    .header-content {
        flex-wrap: wrap;
        gap: var(--spacing-sm);
    }
    
    .header-left {
        flex: 1 1 auto;
        min-width: 0;
    }
    
    .header-right {
        flex: 1 1 100%;
        justify-content: center;
        flex-wrap: wrap;
        gap: var(--spacing-sm);
    }
    
    .photo {
        width: 50px;
        height: 50px;
    }
    
    .name {
        font-size: var(--font-size-base);
    }
    
    .title {
        font-size: var(--font-size-small);
    }
    
    .main-nav {
        order: 1;
    }
    
    .header-actions {
        order: 2;
    }
    
    .contact-info {
        order: 3;
        justify-content: center;
    }
    
    /* Hide sidebar on tablet/mobile, show as overlay menu */
    .cv-sidebar {
        position: fixed;
        left: -200px;
        transition: left var(--transition-base);
        z-index: 1000;
        box-shadow: 2px 0 12px rgba(0, 0, 0, 0.15);
    }
    
    .cv-sidebar.open {
        left: 0;
    }
    
    .main-content-with-sidebar {
        margin-left: 0;
    }
    
    .mobile-menu-toggle {
        display: flex;
    }
    
    .mobile-overlay.active {
        display: block;
    }
    
    .section {
        padding: var(--spacing-md);
    }
    
    .timeline {
        padding-left: var(--spacing-md);
    }
    
    .timeline-item {
        padding-left: var(--spacing-md);
    }
    
    .skills-grid {
        grid-template-columns: 1fr;
    }
    
    .award-item {
        flex-direction: column;
        text-align: center;
    }
    
    .blog-content {
        flex-direction: column;
    }
    
    .blog-image-container {
        width: 100%;
        height: 200px;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 var(--spacing-sm);
    }
    
    .header {
        padding: var(--spacing-sm) 0;
    }
    
    .header-content {
        gap: var(--spacing-xs);
    }
    
    .photo {
        width: 45px;
        height: 45px;
    }
    
    .name {
        font-size: var(--font-size-base);
    }
    
    .title {
        font-size: 0.85rem;
    }
    
    .main-nav {
        gap: var(--spacing-sm);
    }
    
    .nav-link {
        font-size: var(--font-size-small);
    }
    
    .contact-info {
        gap: var(--spacing-xs);
    }
    
    .cv-sidebar {
        width: 180px;
        left: -180px;
    }
}