/* Reset & Base Setup */
     * {
         margin: 0;
         padding: 0;
         box-sizing: border-box;
     }

     * {
         transition: background-color 0.3s ease, border-color 0.3s ease, color 0.3s ease;
     }

     .no-transitions * {
         transition: none !important;
         animation-duration: 0s !important;
     }

     /* CSS Custom Properties */
     :root {
         /* Light Mode Colors */
         --bg-primary: #FAFAFA;
         --bg-secondary: #FFFFFF;
         --bg-elevated: #FFFFFF;
         --text-primary: #1A1A1A;
         --text-secondary: #666666;
         --text-tertiary: #999999;
         --text-muted: #999999;
         --border-light: #E5E5E5;
         --border-medium: #E5E5E5;
         --accent-primary: #B8860B;
         --accent-wine: #B8860B;
         --accent-secondary: #8B7355;
         --shadow-sm: rgba(0, 0, 0, 0.04);
         --shadow-md: rgba(0, 0, 0, 0.08);
         --shadow-lg: rgba(0, 0, 0, 0.12);

         /* 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: 5rem;

         /* Typography Scale */
         --text-xs: 0.75rem;
         --text-sm: 0.875rem;
         --text-base: 1rem;
         --text-lg: 1.125rem;
         --text-xl: 1.25rem;
         --text-2xl: 1.5rem;
         --text-3xl: 1.875rem;
         --text-4xl: 2.25rem;
         --text-5xl: 3rem;
         --text-6xl: 4rem;

         /* Border Radius Scale */
         --radius-sm: 6px;
         --radius-md: 8px;
         --radius-lg: 12px;
         --radius-xl: 16px;
     }

     /* Dark Mode Color Overrides */
     [data-theme="dark"] {
         --bg-primary: #0A0A0A;
         --bg-secondary: #141414;
         --bg-elevated: #1A1A1A;
         --text-primary: #FAFAFA;
         --text-secondary: #A8A8A8;
         --text-tertiary: #707070;
         --text-muted: #606060;
         --border-light: #2A2A2A;
         --border-medium: #333333;
         --accent-primary: #D4AF37;
         --accent-wine: #D4AF37;
         --accent-secondary: #A0906B;
         --shadow-sm: rgba(0, 0, 0, 0.2);
         --shadow-md: rgba(0, 0, 0, 0.4);
         --shadow-lg: rgba(0, 0, 0, 0.6);
     }

     /* Auto Dark Mode Detection */
     @media (prefers-color-scheme: dark) {
         :root:not([data-theme="light"]) {
             --bg-primary: #0A0A0A;
             --bg-secondary: #141414;
             --bg-elevated: #1A1A1A;
             --text-primary: #E5E5E5;
             --text-secondary: #A0A0A0;
             --text-tertiary: #707070;
             --text-muted: #707070;
             --border-light: #2A2A2A;
             --border-medium: #2A2A2A;
             --accent-wine: #D4AF37;
             --shadow-sm: rgba(0, 0, 0, 0.2);
             --shadow-md: rgba(0, 0, 0, 0.4);
             --shadow-lg: rgba(0, 0, 0, 0.6);
         }
     }

     /* Base Document Styles */
     html {
         scroll-behavior: smooth;
         scroll-padding-top: 100px;
     }

     body {
         font-family: -apple-system, BlinkMacSystemFont, 'Helvetica Neue', 'Segoe UI', Arial, sans-serif;
         background-color: var(--bg-primary);
         color: var(--text-primary);
         line-height: 1.7;
         min-height: 100vh;
         transition: background-color 0.4s ease, color 0.4s ease;
         font-size: 16px;
         font-weight: 400;
         letter-spacing: -0.011em;
         -webkit-font-smoothing: antialiased;
         -moz-osx-font-smoothing: grayscale;
         text-rendering: optimizeLegibility;
     }

     ::selection {
         background: var(--accent-primary);
         color: white;
     }

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

     /* Layout Components */
     .container {
         max-width: 1200px;
         margin: 0 auto;
         padding: var(--space-4xl) var(--space-xl);
     }

/* Theme toggle button */
.theme-toggle {
    position: fixed;
    top: var(--space-xl);
    right: var(--space-xl);
    background: var(--bg-elevated);
    border: 1px solid var(--border-light);
    border-radius: 50%;
    padding: 0;
    cursor: pointer;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    width: 48px;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    backdrop-filter: blur(10px);
    box-shadow: 0 2px 12px var(--shadow-md);
    -webkit-backdrop-filter: blur(10px);
    z-index: 1000;
}

.theme-toggle:hover {
    border-color: var(--accent-primary);
    transform: translateY(-1px) rotate(180deg);
    box-shadow: 0 6px 16px var(--shadow-lg);
}

.theme-icon {
    width: 22px;
    height: 22px;
    color: var(--text-primary);
    transition: color 0.3s ease;
}

     /* Header */
     .header {
         text-align: center;
         padding: var(--space-4xl) 0 var(--space-3xl) 0;
         margin-bottom: var(--space-3xl);
     }

     .header h1 {
         font-size: clamp(var(--text-5xl), 8vw, var(--text-6xl));
         font-weight: 200;
         letter-spacing: 0.15em;
         text-transform: uppercase;
         color: var(--text-primary);
         line-height: 1;
         margin-bottom: var(--space-lg);
     }

     .header-subtitle {
         color: var(--text-secondary);
         font-size: var(--text-lg);
         letter-spacing: 0.08em;
         text-transform: uppercase;
         font-weight: 400;
         line-height: 1.4;
     }

     /* Navigation Grid */
     .nav-grid {
         display: grid;
         gap: var(--space-2xl);
         grid-template-columns: 1fr;
         max-width: 800px;
         margin: 0 auto;
     }

     @media (min-width: 768px) {
         .nav-grid {
             grid-template-columns: 1fr 1fr;
         }
     }

     @media (min-width: 1024px) {
         .nav-grid {
             grid-template-columns: 1fr 1fr 1fr;
         }
     }

     /* Navigation Cards */
     .nav-card {
         background: var(--bg-elevated);
         border: 1px solid var(--border-light);
         border-radius: var(--radius-lg);
         padding: var(--space-2xl);
         text-decoration: none;
         color: inherit;
         transition: all 0.6s cubic-bezier(0.23, 1, 0.32, 1);
         display: block;
         position: relative;
         overflow: hidden;
         transform: translateY(0);
         box-shadow: 0 2px 8px var(--shadow-sm);
     }

     .nav-card:hover {
         transform: translateY(-2px);
         box-shadow: 0 8px 24px var(--shadow-md);
         border-color: var(--border-medium);
     }

     .nav-card::before {
         content: '';
         position: absolute;
         top: 0;
         left: 0;
         right: 0;
         height: 1px;
         background: linear-gradient(90deg, transparent, var(--accent-primary), transparent);
         transform: scaleX(0);
         transition: transform 0.8s cubic-bezier(0.23, 1, 0.32, 1);
         opacity: 0.6;
     }

     .nav-card:hover::before {
         transform: scaleX(1);
     }

     /* Subtle glow effect on hover */
     .nav-card::after {
         content: '';
         position: absolute;
         top: -2px;
         left: -2px;
         right: -2px;
         bottom: -2px;
         background: linear-gradient(45deg, var(--accent-primary), transparent, var(--accent-primary));
         border-radius: var(--radius-lg);
         opacity: 0;
         transition: opacity 1s cubic-bezier(0.23, 1, 0.32, 1);
         z-index: -1;
         filter: blur(8px);
     }

     .nav-card:hover::after {
         opacity: 0.15;
     }

     .nav-card-icon {
         font-size: var(--text-3xl);
         margin-bottom: var(--space-lg);
         display: block;
         transition: transform 0.8s cubic-bezier(0.23, 1, 0.32, 1);
         transform-origin: center;
     }

     .nav-card:hover .nav-card-icon {
         transform: scale(1.05) translateY(-2px);
     }

     .nav-card h2 {
         font-size: var(--text-2xl);
         font-weight: 300;
         letter-spacing: 0.05em;
         text-transform: uppercase;
         margin-bottom: var(--space-md);
         color: var(--text-primary);
         transition: color 0.6s cubic-bezier(0.23, 1, 0.32, 1);
     }

     .nav-card:hover h2 {
         color: var(--accent-primary);
     }

     .nav-card p {
         color: var(--text-secondary);
         font-size: var(--text-base);
         line-height: 1.6;
         margin-bottom: var(--space-lg);
         transition: color 0.6s cubic-bezier(0.23, 1, 0.32, 1);
     }

     .nav-card:hover p {
         color: var(--text-primary);
     }

     .nav-card-footer {
         display: flex;
         align-items: center;
         justify-content: space-between;
         margin-top: auto;
         padding-top: var(--space-lg);
         border-top: 1px solid var(--border-light);
     }

     .nav-card-status {
         color: var(--text-tertiary);
         font-size: var(--text-sm);
         text-transform: uppercase;
         letter-spacing: 0.05em;
         font-weight: 500;
     }

     .nav-card-arrow {
         color: var(--accent-primary);
         transition: all 0.8s cubic-bezier(0.23, 1, 0.32, 1);
         font-size: var(--text-lg);
     }

     .nav-card:hover .nav-card-arrow {
         transform: translateX(6px) scale(1.1);
         opacity: 0.8;
     }

     /* Special styling for Bar 820 card */
     .nav-card.bar-card {
         background: linear-gradient(135deg, var(--bg-elevated) 0%, var(--bg-secondary) 100%);
         position: relative;
     }

     .nav-card.bar-card::before {
         background: linear-gradient(90deg, transparent, var(--accent-wine), transparent);
     }

     [data-theme="dark"] .nav-card.bar-card {
         background: linear-gradient(135deg, var(--bg-elevated) 0%, #1F1F1F 100%);
     }

     /* Breathing animation for Bar 820 card */
     .nav-card.bar-card {
         animation: subtle-pulse 6s ease-in-out infinite;
     }

     @keyframes subtle-pulse {

         0%,
         100% {
             box-shadow: 0 2px 8px var(--shadow-sm);
         }

         50% {
             box-shadow: 0 4px 12px var(--shadow-md);
         }
     }

     /* Footer */
     .footer {
         text-align: center;
         margin-top: var(--space-4xl);
         padding-top: var(--space-2xl);
         border-top: 1px solid var(--border-light);
         color: var(--text-muted);
         font-size: var(--text-sm);
     }

     /* Animations */
     .fade-in {
         animation: fadeIn 1.2s cubic-bezier(0.23, 1, 0.32, 1) forwards;
         opacity: 0;
     }

     @keyframes fadeIn {
         from {
             opacity: 0;
             transform: translateY(40px);
         }

         to {
             opacity: 1;
             transform: translateY(0);
         }
     }

     .nav-card:nth-child(1) {
         animation-delay: 0.2s;
     }

     .nav-card:nth-child(2) {
         animation-delay: 0.4s;
     }

     .nav-card:nth-child(3) {
         animation-delay: 0.6s;
     }

     /* Parallax effect on scroll */
     .header {
         transition: transform 0.6s cubic-bezier(0.23, 1, 0.32, 1);
     }

     /* Micro-interaction: Status indicator pulse */
     .nav-card-status {
         color: var(--text-tertiary);
         font-size: var(--text-sm);
         text-transform: uppercase;
         letter-spacing: 0.05em;
         font-weight: 500;
         position: relative;
         transition: color 0.6s cubic-bezier(0.23, 1, 0.32, 1);
     }

     /* .nav-card-status::before {
         content: '';
         position: absolute;
         left: -12px;
         top: 50%;
         transform: translateY(-50%);
         width: 4px;
         height: 4px;
         background: var(--accent-primary);
         border-radius: 50%;
         opacity: 0;
         transition: opacity 0.8s cubic-bezier(0.23, 1, 0.32, 1);
     }

     .nav-card:hover .nav-card-status::before {
         opacity: 1;
     } */

     @keyframes pulse-dot {

         0%,
         100% {
             transform: translateY(-50%) scale(1);
             opacity: 1;
         }

         50% {
             transform: translateY(-50%) scale(1.2);
             opacity: 0.7;
         }
     }

     /* Accessibility & Keyboard Navigation */
     .keyboard-navigation .nav-card:focus {
         outline: 2px solid var(--accent-primary);
         outline-offset: 4px;
         transform: translateY(-1px);
     }

     /* Reduced motion preferences */
     @media (prefers-reduced-motion: reduce) {
         * {
             animation-duration: 0.01ms !important;
             animation-iteration-count: 1 !important;
             transition-duration: 0.01ms !important;
             scroll-behavior: auto !important;
         }

         .nav-card.bar-card {
             animation: none;
         }
     }

     /* Loading state */
     body:not(.loaded) .fade-in {
         opacity: 0;
     }

     /* Enhanced focus states */
     .theme-toggle:focus-visible {
         outline: 2px solid var(--accent-primary);
         outline-offset: 4px;
     }

     @media (max-width: 768px) {
         .container {
             padding: var(--space-3xl) var(--space-lg);
         }

         .theme-toggle {
             width: 44px;
             height: 44px;
             top: var(--space-md);
             right: var(--space-md);
         }

         .nav-card {
             padding: var(--space-xl);
         }
     }
     /* Language Toggle Button */
     .lang-toggle {
        position: fixed;
        top: var(--space-xl);
        left: var(--space-xl);
        background: var(--bg-elevated, #ffffff);
        border: 1px solid var(--border-light);
        border-radius: 50%;
        width: 48px;
        height: 48px;
        min-width: 44px;
        max-width: 44px;
        padding: 0;
        display: flex;
        align-items: center;
        justify-content: center;
        cursor: pointer;
        z-index: 997;
        transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
        backdrop-filter: blur(10px);
        -webkit-backdrop-filter: blur(10px);
        /* Prevent any flex or grid parent from stretching it */
        flex-shrink: 0;
        flex-grow: 0;
    }
    
    .lang-toggle:hover {
        border-color: var(--accent-primary);
        transform: translateY(-1px) rotate(360deg);
        box-shadow: 0 6px 16px var(--shadow-lg);
    }
    
    .lang-text {
        font-size: 0.75rem;
        font-weight: 600;
        letter-spacing: 0.05em;
        color: var(--text-primary, #333333);
        text-transform: uppercase;
        /* Ensure text doesn't get selected on click */
        user-select: none;
        white-space: nowrap;
    }
    
    /* Add focus styles for accessibility */
    .lang-toggle:focus-visible {
        outline: 2px solid var(--accent-primary, #4A90E2);
        outline-offset: 2px;
    }
    
    /* Add active state for better interaction feedback */
    .lang-toggle:active {
        transform: translateY(0);
        box-shadow: 0 2px 10px rgba(0, 0, 0, 0.08);
    }

/* Adjust positioning on mobile */
@media (max-width: 768px) {
    .lang-toggle {
        top: 1rem;
        height: 44px;
        width: 44px;
        left: 1rem;
    }
}
.lang-toggle:focus-visible {
    outline: 2px solid var(--accent-primary, #4A90E2);
    outline-offset: 2px;
}

/* Active state */
.lang-toggle:active {
    transform: translateY(0);
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.08);
}
/* Adjust when nav is open */
body.nav-open .lang-toggle {
    opacity: 0.3;
    pointer-events: none;
}

/* Font stack with CJK support */
body {
    font-family: -apple-system, BlinkMacSystemFont, 'Helvetica Neue', Arial, 
                 'Noto Sans CJK TC', 'Microsoft YaHei', 'Hiragino Sans', 
                 'Meiryo', sans-serif;
}

/* Adjust font weights for CJK languages */
[data-lang="zh"] body,
[data-lang="ja"] body {
    font-weight: 400;
}

[data-lang="zh"] h1,
[data-lang="ja"] h1 {
    font-weight: 300;
}
/* Adjust line height for CJK languages */
[data-lang="zh"] .itemList li,
[data-lang="ja"] .itemList li {
    line-height: 1.8;
}

/* Slightly smaller font size for longer Japanese text */
[data-lang="ja"] .itemList a {
    font-size: 0.9rem;
}

/* Ensure proper spacing for mixed English/CJK text */
[data-lang="zh"] .itemList a,
[data-lang="ja"] .itemList a {
    word-spacing: 0.1em;
}