/* ============================================
DESIGN TOKENS - FUTURISTIC LIGHT THEME
============================================ */
 :root {
     /* Base Colors - Light Theme */
     --color-bg-primary: #fafbfc;
     --color-bg-secondary: #f5f7fa;
     --color-surface: #ffffff;
     --color-text-primary: #1a202c;
     --color-text-secondary: #4a5568;
     --color-text-muted: #718096;

     /* Theme Accents - Research/Technology Theme */
     --color-accent-1: #667eea;
     --color-accent-2: #764ba2;
     --color-accent-3: #f093fb;
     --color-accent-light: #f5f3ff;
     --color-accent-hover: #5a67d8;

     /* Functional Colors */
     --color-updated-badge: #f56565;
     --color-success: #48bb78;
     --color-border: rgba(102, 126, 234, 0.15);
     --color-shadow: rgba(102, 126, 234, 0.12);

     /* Gradients */
     --gradient-primary: linear-gradient(135deg, var(--color-accent-1) 0%, var(--color-accent-2) 100%);
     --gradient-subtle: linear-gradient(180deg, var(--color-bg-primary) 0%, var(--color-accent-light) 100%);
     --gradient-glass: linear-gradient(135deg, rgba(255, 255, 255, 0.9) 0%, rgba(255, 255, 255, 0.7) 100%);

     /* Spacing Scale */
     --space-xs: 0.25rem;
     --space-sm: 0.5rem;
     --space-md: 1rem;
     --space-lg: 1.5rem;
     --space-xl: 2rem;
     --space-2xl: 3rem;
     --space-3xl: 4rem;
     --space-4xl: 6rem;

     /* Border Radius */
     --radius-sm: 8px;
     --radius-md: 12px;
     --radius-lg: 16px;
     --radius-xl: 24px;
     --radius-full: 9999px;

     /* Shadows */
     --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.04), 0 1px 2px rgba(0, 0, 0, 0.06);
     --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.05), 0 2px 4px rgba(0, 0, 0, 0.06);
     --shadow-lg: 0 10px 24px var(--color-shadow), 0 4px 8px rgba(0, 0, 0, 0.06);
     --shadow-xl: 0 20px 40px var(--color-shadow), 0 8px 16px rgba(0, 0, 0, 0.08);

     /* Typography */
     --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Helvetica Neue', Arial, sans-serif;
     --text-xs: clamp(0.75rem, 0.7rem + 0.25vw, 0.875rem);
     --text-sm: clamp(0.875rem, 0.8rem + 0.35vw, 1rem);
     --text-base: clamp(1rem, 0.95rem + 0.25vw, 1.125rem);
     --text-lg: clamp(1.125rem, 1.05rem + 0.35vw, 1.25rem);
     --text-xl: clamp(1.25rem, 1.15rem + 0.5vw, 1.5rem);
     --text-2xl: clamp(1.5rem, 1.3rem + 1vw, 2rem);
     --text-3xl: clamp(2rem, 1.6rem + 2vw, 3rem);
     --text-4xl: clamp(2.5rem, 2rem + 2.5vw, 4rem);

     /* Transitions */
     --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
     --transition-base: 300ms cubic-bezier(0.4, 0, 0.2, 1);
     --transition-slow: 500ms cubic-bezier(0.4, 0, 0.2, 1);
 }

 /* ============================================
RESET & BASE STYLES
============================================ */
 *,
 *::before,
 *::after {
     box-sizing: border-box;
     margin: 0;
     padding: 0;
 }

 html {
     scroll-behavior: smooth;
     scroll-padding-top: 120px;
 }

 body {
     font-family: var(--font-sans);
     font-size: var(--text-base);
     line-height: 1.6;
     color: var(--color-text-primary);
     background: var(--gradient-subtle);
     background-attachment: fixed;
     min-height: 100vh;
     -webkit-font-smoothing: antialiased;
     -moz-osx-font-smoothing: grayscale;
 }

 /* Animated Background Pattern */
 body::before {
     content: '';
     position: fixed;
     top: 0;
     left: 0;
     width: 100%;
     height: 100%;
     background-image:
         radial-gradient(circle at 20% 50%, rgba(102, 126, 234, 0.03) 0%, transparent 50%),
         radial-gradient(circle at 80% 80%, rgba(118, 75, 162, 0.03) 0%, transparent 50%);
     pointer-events: none;
     z-index: 0;
 }

 /* ============================================
LAYOUT STRUCTURE
============================================ */
 .page-container {
     position: relative;
     z-index: 1;
     max-width: 1400px;
     margin: 0 auto;
     padding: var(--space-xl);
 }

 /* ============================================
GLASSMORPHISM HEADER
============================================ */
 .header {
     position: sticky;
     top: 0;
     z-index: 100;
     background: rgba(255, 255, 255, 0.8);
     -webkit-backdrop-filter: blur(20px) saturate(180%);
     backdrop-filter: blur(20px) saturate(180%);
     border-bottom: 1px solid var(--color-border);
     box-shadow: var(--shadow-md);
     margin: calc(var(--space-xl) * -1);
     margin-bottom: var(--space-3xl);
     padding: var(--space-lg) var(--space-xl);
 }

 .header-content {
     max-width: 1400px;
     margin: 0 auto;
     display: flex;
     align-items: center;
     justify-content: space-between;
     flex-wrap: wrap;
     gap: var(--space-lg);
 }

 .site-title {
     font-size: var(--text-3xl);
     font-weight: 800;
     letter-spacing: -0.02em;
     background: var(--gradient-primary);
     -webkit-background-clip: text;
     -webkit-text-fill-color: transparent;
     background-clip: text;
     animation: gradientShift 8s ease infinite;
     background-size: 200% 200%;
 }

 @keyframes gradientShift {

     0%,
     100% {
         background-position: 0% 50%;
     }

     50% {
         background-position: 100% 50%;
     }
 }

 .breadcrumb {
     list-style: none;
     display: flex;
     gap: var(--space-sm);
     font-size: var(--text-sm);
     color: var(--color-text-secondary);
 }

 .breadcrumb a {
     color: var(--color-accent-1);
     text-decoration: none;
     transition: color var(--transition-fast);
 }

 .breadcrumb a:hover {
     color: var(--color-accent-hover);
 }

 /* ============================================
INFO BANNER
============================================ */
 .info-banner {
     background: var(--gradient-glass);
     -webkit-backdrop-filter: blur(12px) saturate(180%);
     backdrop-filter: blur(12px) saturate(180%);
     border: 1px solid rgba(255, 255, 255, 0.3);
     border-radius: var(--radius-lg);
     padding: var(--space-lg);
     margin-bottom: var(--space-2xl);
     box-shadow: var(--shadow-md);
 }

 .info-banner p {
     margin: 0;
     color: var(--color-text-secondary);
 }

 .info-banner a {
     color: var(--color-accent-1);
     text-decoration: none;
     font-weight: 600;
     transition: color var(--transition-fast);
 }

 .info-banner a:hover {
     color: var(--color-accent-hover);
 }

 /* ============================================
SEARCH & FILTER BAR
============================================ */
 .filter-bar {
     background: var(--gradient-glass);
     -webkit-backdrop-filter: blur(12px) saturate(180%);
     backdrop-filter: blur(12px) saturate(180%);
     border: 1px solid rgba(255, 255, 255, 0.3);
     border-radius: var(--radius-lg);
     padding: var(--space-xl);
     margin-bottom: var(--space-3xl);
     box-shadow: var(--shadow-lg);
 }

 .filter-grid {
     display: grid;
     grid-template-columns: 2fr 1fr;
     gap: var(--space-md);
     margin-bottom: var(--space-lg);
 }

 .search-box {
     position: relative;
 }

 .search-input {
     width: 100%;
     padding: var(--space-md) var(--space-md) var(--space-md) var(--space-3xl);
     border: 2px solid var(--color-border);
     border-radius: var(--radius-md);
     font-size: var(--text-base);
     font-family: var(--font-sans);
     background: var(--color-surface);
     color: var(--color-text-primary);
     transition: all var(--transition-base);
 }

 .search-input:focus {
     outline: none;
     border-color: var(--color-accent-1);
     box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
 }

 .search-icon {
     position: absolute;
     left: var(--space-md);
     top: 50%;
     transform: translateY(-50%);
     width: 20px;
     height: 20px;
     color: var(--color-text-muted);
 }

 .filter-select {
     padding: var(--space-md);
     border: 2px solid var(--color-border);
     border-radius: var(--radius-md);
     font-size: var(--text-base);
     font-family: var(--font-sans);
     background: var(--color-surface);
     color: var(--color-text-primary);
     cursor: pointer;
     transition: all var(--transition-base);
 }

 .filter-select:focus {
     outline: none;
     border-color: var(--color-accent-1);
     box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
 }

 /* ============================================
YEAR NAVIGATION
============================================ */
 .year-nav {
     display: flex;
     gap: var(--space-sm);
     padding: var(--space-md);
     background: rgba(255, 255, 255, 0.5);
     border-radius: var(--radius-md);
     overflow-x: auto;
     scrollbar-width: thin;
     scrollbar-color: var(--color-accent-1) transparent;
 }

 .year-nav::-webkit-scrollbar {
     height: 6px;
 }

 .year-nav::-webkit-scrollbar-track {
     background: transparent;
 }

 .year-nav::-webkit-scrollbar-thumb {
     background: var(--color-accent-1);
     border-radius: var(--radius-full);
 }

 .year-link {
     padding: var(--space-sm) var(--space-lg);
     background: white;
     color: var(--color-accent-1);
     text-decoration: none;
     border-radius: var(--radius-md);
     font-weight: 600;
     white-space: nowrap;
     transition: all var(--transition-base);
     border: 2px solid var(--color-border);
 }

 .year-link:hover {
     background: var(--color-accent-1);
     color: white;
     border-color: var(--color-accent-2);
     transform: translateY(-2px);
     box-shadow: var(--shadow-md);
 }

 /* ============================================
YEAR SECTIONS
============================================ */
 .years-container {
     display: flex;
     flex-direction: column;
     gap: var(--space-3xl);
 }

 .year-section {
     background: var(--gradient-glass);
     -webkit-backdrop-filter: blur(12px) saturate(180%);
     backdrop-filter: blur(12px) saturate(180%);
     border: 1px solid rgba(255, 255, 255, 0.3);
     border-radius: var(--radius-xl);
     padding: var(--space-2xl);
     box-shadow: var(--shadow-lg);
     transition: all var(--transition-slow);
 }

 .year-section:hover {
     box-shadow: var(--shadow-xl);
     transform: translateY(-4px);
 }

 .year-header {
     display: flex;
     justify-content: space-between;
     align-items: center;
     margin-bottom: var(--space-xl);
     padding-bottom: var(--space-lg);
     border-bottom: 2px solid var(--color-border);
 }

 .year-title {
     font-size: var(--text-2xl);
     font-weight: 700;
     color: var(--color-accent-1);
     letter-spacing: -0.01em;
 }

 .year-count {
     padding: var(--space-xs) var(--space-md);
     background: var(--color-accent-light);
     color: var(--color-accent-1);
     border-radius: var(--radius-full);
     font-size: var(--text-sm);
     font-weight: 600;
 }

 /* ============================================
ARTICLE LIST
============================================ */
 .article-list {
     list-style: none;
     display: flex;
     flex-direction: column;
     gap: var(--space-lg);
 }

 .article-item {
     background: white;
     border-radius: var(--radius-md);
     padding: var(--space-lg);
     transition: all var(--transition-base);
     border: 2px solid transparent;
     position: relative;
     overflow: hidden;
 }

 .article-item::before {
     content: '';
     position: absolute;
     top: 0;
     left: 0;
     width: 4px;
     height: 100%;
     background: var(--gradient-primary);
     transform: scaleY(0);
     transition: transform var(--transition-base);
 }

 .article-item:hover {
     border-color: var(--color-accent-1);
     box-shadow: var(--shadow-md);
     transform: translateX(4px);
 }

 .article-item:hover::before {
     transform: scaleY(1);
 }

 .article-main {
     display: flex;
     align-items: center;
     gap: var(--space-md);
     margin-bottom: var(--space-sm);
 }

 .article-link {
     text-decoration: none;
     color: var(--color-text-primary);
     flex: 1;
 }

 .article-title {
     font-size: var(--text-lg);
     font-weight: 600;
     line-height: 1.4;
     transition: color var(--transition-fast);
 }

 .article-link:hover .article-title {
     color: var(--color-accent-1);
 }

 .updated-badge {
     font-size: var(--text-sm);
     animation: pulse 2s ease-in-out infinite;
 }

 @keyframes pulse {

     0%,
     100% {
         opacity: 1;
         transform: scale(1);
     }

     50% {
         opacity: 0.7;
         transform: scale(1.1);
     }
 }

 .article-meta {
     display: flex;
     gap: var(--space-lg);
     flex-wrap: wrap;
     font-size: var(--text-sm);
     color: var(--color-text-muted);
 }

 .meta-item {
     display: flex;
     align-items: center;
     gap: var(--space-xs);
 }

 .meta-icon {
     width: 16px;
     height: 16px;
     stroke-width: 2;
 }

 .creation-date {
     color: var(--color-accent-1);
     font-weight: 600;
 }

 .modified-date {
     color: var(--color-text-secondary);
 }

 .reading-time {
     color: var(--color-success);
 }

 .word-count {
     color: var(--color-text-muted);
 }

 /* ============================================
RESPONSIVE DESIGN
============================================ */
 @media (max-width: 768px) {
     :root {
         --space-xl: 1.5rem;
         --space-2xl: 2rem;
         --space-3xl: 2.5rem;
         --space-4xl: 3rem;
     }

     .page-container {
         padding: var(--space-md);
     }

     .header {
         margin: calc(var(--space-md) * -1);
         margin-bottom: var(--space-xl);
         padding: var(--space-md);
     }

     .header-content {
         flex-direction: column;
         align-items: flex-start;
     }

     .filter-grid {
         grid-template-columns: 1fr;
     }

     .filter-bar {
         padding: var(--space-lg);
     }

     .year-section {
         padding: var(--space-lg);
     }

     .article-meta {
         gap: var(--space-sm);
     }
 }

 @media (max-width: 480px) {
     .article-meta {
         flex-direction: column;
         gap: var(--space-xs);
     }
 }

 /* ============================================
ACCESSIBILITY
============================================ */
 @media (prefers-reduced-motion: reduce) {
     * {
         animation-duration: 0.01ms !important;
         animation-iteration-count: 1 !important;
         transition-duration: 0.01ms !important;
     }

     html {
         scroll-behavior: auto;
     }
 }

 *:focus-visible {
     outline: 3px solid var(--color-accent-1);
     outline-offset: 2px;
 }

 /* ============================================
UTILITY CLASSES
============================================ */
 .hidden {
     display: none !important;
 }