/* ============================================
   DESIGN TOKENS & CSS VARIABLES
   ============================================ */

:root {
    /* Colors - Light Theme */
    --color-primary: #1a5490;
    --color-primary-dark: #0f3d6b;
    --color-primary-light: #4a7bb3;
    
    --color-accent: #d84315;
    --color-accent-light: #ff6e40;
    
    --color-bg: #fafafa;
    --color-surface: #ffffff;
    --color-surface-hover: #f5f5f5;
    
    --color-text: #1a1a1a;
    --color-text-secondary: #4a4a4a;
    --color-text-muted: #737373;
    
    --color-border: #e0e0e0;
    --color-border-light: #f0f0f0;
    
    /* Shadows */
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.08);
    --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.12);
    
    /* Typography */
    --font-display: 'Libre Baskerville', Georgia, serif;
    --font-body: 'Work Sans', -apple-system, system-ui, sans-serif;
    
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 2rem;
    --font-size-4xl: 2.5rem;
    
    /* Spacing */
    --space-xs: 0.5rem;
    --space-sm: 0.75rem;
    --space-md: 1rem;
    --space-lg: 1.5rem;
    --space-xl: 2rem;
    --space-2xl: 3rem;
    --space-3xl: 4rem;
    
    /* Layout */
    --max-width-content: 1200px;
    --max-width-prose: 65ch;
    --border-radius: 12px;
    --border-radius-sm: 8px;
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    --transition-slow: 400ms ease;
}

/* Dark Theme */
[data-theme="dark"] {
    --color-primary: #5a9fd4;
    --color-primary-dark: #4a8ec4;
    --color-primary-light: #7ab5e0;
    
    --color-accent: #ff6e40;
    --color-accent-light: #ff8a65;
    
    --color-bg: #0a0a0a;
    --color-surface: #1a1a1a;
    --color-surface-hover: #242424;
    
    --color-text: #f5f5f5;
    --color-text-secondary: #d4d4d4;
    --color-text-muted: #a3a3a3;
    
    --color-border: #2a2a2a;
    --color-border-light: #1f1f1f;
    
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.5);
}

/* ============================================
   BASE STYLES
   ============================================ */

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

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

/* ============================================
   THEME TOGGLE
   ============================================ */

.theme-toggle {
    position: fixed;
    top: var(--space-lg);
    right: var(--space-lg);
    z-index: 1000;
    width: 44px;
    height: 44px;
    border: none;
    border-radius: 50%;
    background: var(--color-surface);
    box-shadow: var(--shadow-md);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-base);
}

.theme-toggle:hover {
    transform: scale(1.1);
    box-shadow: var(--shadow-lg);
}

.theme-toggle svg {
    position: absolute;
    transition: all var(--transition-base);
}

.sun-icon {
    opacity: 1;
    transform: rotate(0deg);
}

.moon-icon {
    opacity: 0;
    transform: rotate(180deg);
}

[data-theme="dark"] .sun-icon {
    opacity: 0;
    transform: rotate(-180deg);
}

[data-theme="dark"] .moon-icon {
    opacity: 1;
    transform: rotate(0deg);
}

/* ============================================
   NAVIGATION
   ============================================ */

.nav {
    position: sticky;
    top: 0;
    z-index: 100;
    background: var(--color-surface);
    border-bottom: 1px solid var(--color-border);
    backdrop-filter: blur(12px);
    transition: all var(--transition-base);
}

.nav-container {
    max-width: var(--max-width-content);
    margin: 0 auto;
    padding: var(--space-md) var(--space-xl);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-brand {
    font-family: var(--font-display);
    font-size: var(--font-size-xl);
    font-weight: 700;
    color: var(--color-text);
    text-decoration: none;
    transition: color var(--transition-fast);
}

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

.nav-links {
    display: flex;
    gap: var(--space-lg);
}

.nav-link {
    font-size: var(--font-size-sm);
    font-weight: 500;
    color: var(--color-text-secondary);
    text-decoration: none;
    padding: var(--space-xs) var(--space-sm);
    border-radius: var(--border-radius-sm);
    transition: all var(--transition-fast);
    letter-spacing: 0.02em;
    text-transform: uppercase;
    font-size: 0.8rem;
}

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

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

/* ============================================
   HERO SECTION
   ============================================ */

.hero {
    padding: var(--space-3xl) var(--space-xl);
    background: linear-gradient(135deg, var(--color-surface) 0%, var(--color-bg) 100%);
    border-bottom: 1px solid var(--color-border);
}

.hero-content {
    max-width: var(--max-width-content);
    margin: 0 auto;
}

.hero-title {
    font-family: var(--font-display);
    font-size: var(--font-size-4xl);
    font-weight: 700;
    color: var(--color-text);
    margin-bottom: var(--space-md);
    line-height: 1.2;
}

.hero-lead {
    font-size: var(--font-size-xl);
    color: var(--color-text-secondary);
    max-width: 60ch;
}

/* ============================================
   LAYOUT CONTAINERS
   ============================================ */

.container {
    max-width: var(--max-width-content);
    margin: 0 auto;
    padding: 0 var(--space-xl);
}

.main {
    padding: var(--space-3xl) 0;
}

.content-grid {
    display: grid;
    grid-template-columns: 1fr 350px;
    gap: var(--space-3xl);
    align-items: start;
}

.content-main {
    min-width: 0;
}

/* ============================================
   SECTIONS
   ============================================ */

.section {
    margin-bottom: var(--space-3xl);
}

.section-title {
    font-family: var(--font-display);
    font-size: var(--font-size-2xl);
    font-weight: 700;
    color: var(--color-text);
    margin-bottom: var(--space-xl);
}

/* ============================================
   PROSE / TYPOGRAPHY
   ============================================ */

.prose {
    max-width: var(--max-width-prose);
}

.prose p {
    margin-bottom: var(--space-lg);
    color: var(--color-text-secondary);
    line-height: 1.8;
}

.prose strong {
    color: var(--color-text);
    font-weight: 600;
}

.prose a {
    color: var(--color-primary);
    text-decoration: none;
    border-bottom: 1px solid transparent;
    transition: border-color var(--transition-fast);
}

.prose a:hover {
    border-bottom-color: var(--color-primary);
}

/* ============================================
   CARDS
   ============================================ */

.card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    padding: var(--space-xl);
    transition: all var(--transition-base);
}

.card:hover {
    box-shadow: var(--shadow-md);
    border-color: var(--color-primary-light);
    transform: translateY(-2px);
}

.card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--space-lg);
}

.card-header {
    margin-bottom: var(--space-md);
}

.card-title {
    font-family: var(--font-display);
    font-size: var(--font-size-lg);
    font-weight: 700;
    color: var(--color-text);
    margin-bottom: var(--space-sm);
}

.card-text {
    color: var(--color-text-secondary);
    line-height: 1.6;
    font-size: var(--font-size-sm);
}

/* ============================================
   TAGS
   ============================================ */

.tag {
    display: inline-block;
    padding: var(--space-xs) var(--space-md);
    background: var(--color-primary);
    color: white;
    font-size: var(--font-size-xs);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    border-radius: 4px;
}

.tag-light {
    display: inline-block;
    padding: var(--space-xs) var(--space-md);
    background: white;
    color: var(--color-primary-dark);
    font-size: var(--font-size-xs);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    border-radius: 4px;
    border-color: var(--color-border);
    border: 1px solid var(--color-border);
}

/* ============================================
   SIDEBAR
   ============================================ */

.sidebar {
    position: sticky;
    top: 100px;
}

.sidebar-card {
    margin-bottom: var(--space-md);
}

.sidebar-card:hover {
    transform: none;
}

.sidebar-title {
    font-family: var(--font-display);
    font-size: var(--font-size-lg);
    font-weight: 700;
    color: var(--color-text);
    margin-bottom: var(--space-lg);
    padding-bottom: var(--space-md);
    border-bottom: 2px solid var(--color-border);
}

/* ============================================
   CONTACT INFO
   ============================================ */

.contact-info {
    display: flex;
    flex-direction: column;
    gap: var(--space-lg);
}

.contact-item {
    display: flex;
    gap: var(--space-md);
    align-items: flex-start;
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    line-height: 1.6;
}

.contact-icon {
    flex-shrink: 0;
    margin-top: 2px;
    color: var(--color-primary);
}

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

.contact-item a:hover {
    color: var(--color-primary-dark);
    text-decoration: underline;
}

/* ============================================
   SOCIAL LINKS
   ============================================ */

.social-links {
    display: flex;
    flex-direction: column;
    gap: var(--space-sm);
}

.social-link {
    display: flex;
    align-items: center;
    gap: var(--space-md);
    padding: var(--space-sm) var(--space-md);
    color: var(--color-text-secondary);
    text-decoration: none;
    border-radius: var(--border-radius-sm);
    transition: all var(--transition-fast);
    font-size: var(--font-size-sm);
}

.social-link:hover {
    background: var(--color-surface-hover);
    color: var(--color-primary);
    transform: translateX(4px);
}

.social-link svg {
    flex-shrink: 0;
}

/* ============================================
   AFFILIATION
   ============================================ */

.affiliation-text {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    margin-bottom: var(--space-xs);
}

.affiliation-org {
    font-family: var(--font-display);
    font-size: var(--font-size-base);
    font-weight: 600;
    color: var(--color-text);
}

/* ============================================
   FOOTER
   ============================================ */

.footer {
    margin-top: var(--space-3xl);
    padding: var(--space-2xl) var(--space-xl);
    background: var(--color-surface);
    border-top: 1px solid var(--color-border);
}

.footer-content {
    max-width: var(--max-width-content);
    margin: 0 auto;
    text-align: center;
    font-size: var(--font-size-sm);
    color: var(--color-text-muted);
}

.footer-update {
    margin-top: var(--space-xs);
    font-size: var(--font-size-xs);
}

/* ============================================
   RESPONSIVE DESIGN
   ============================================ */

@media (max-width: 1024px) {
    .content-grid {
        grid-template-columns: 1fr;
        gap: var(--space-2xl);
    }
    
    .sidebar {
        position: static;
    }
    
    .sidebar-card {
        max-width: 600px;
    }
}

@media (max-width: 768px) {
    .nav-container {
        flex-direction: column;
        gap: var(--space-md);
        padding: var(--space-md);
    }
    
    .nav-links {
        gap: var(--space-sm);
        flex-wrap: wrap;
        justify-content: center;
    }
    
    .hero {
        padding: var(--space-2xl) var(--space-md);
    }
    
    .hero-title {
        font-size: var(--font-size-3xl);
    }
    
    .hero-lead {
        font-size: var(--font-size-lg);
    }
    
    .hero-details {
        font-size: var(--font-size-sm);
        display: inline-block;
        color: var(--color-primary-light);
        font-weight: 300;
        text-transform: uppercase;
    }

    .container {
        padding: 0 var(--space-md);
    }
    
    .card-grid {
        grid-template-columns: 1fr;
    }
    
    .theme-toggle {
        top: var(--space-md);
        right: var(--space-md);
    }
}

/* ============================================
   ANIMATIONS
   ============================================ */

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.card,
.sidebar-card {
    animation: fadeIn 0.5s ease backwards;
}

.card:nth-child(1) { animation-delay: 0.1s; }
.card:nth-child(2) { animation-delay: 0.2s; }
.card:nth-child(3) { animation-delay: 0.3s; }

.sidebar-card:nth-child(1) { animation-delay: 0.2s; }
.sidebar-card:nth-child(2) { animation-delay: 0.3s; }
.sidebar-card:nth-child(3) { animation-delay: 0.4s; }