/* CSS Custom Properties */
:root {
    /* Colors - Based on Puente Scientific brand */
    --primary-teal: #2D8B8B;
    --primary-teal-bright: #3BB3B3; /* 25% brighter and more vivid */
    --primary-dark: #1A5F5F;
    --primary-light: #4DAAAA;
    --accent-primary: #00D4AA;
    --accent-secondary: #00B894;
    
    /* Neutral Colors */
    --white: #FFFFFF;
    --black: #000000;
    --gray-50: #F8FAFC;
    --gray-100: #F1F5F9;
    --gray-200: #E2E8F0;
    --gray-300: #CBD5E1;
    --gray-400: #94A3B8;
    --gray-500: #64748B;
    --gray-600: #475569;
    --gray-700: #334155;
    --gray-800: #1E293B;
    --gray-900: #0F172A;
    
    /* Semantic Colors */
    --bg-primary: var(--white);
    --bg-secondary: var(--gray-50);
    --bg-tertiary: var(--gray-100);
    --bg-dark: var(--gray-900);
    --bg-overlay: rgba(15, 23, 42, 0.8);
    
    --text-primary: var(--gray-900);
    --text-secondary: var(--gray-600);
    --text-tertiary: var(--gray-400);
    --text-inverse: var(--white);
    
    --border-primary: var(--gray-200);
    --border-secondary: var(--gray-300);
    
    /* Typography */
    --font-primary: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-heading: 'Space Grotesk', var(--font-primary);
    --font-cursive: 'Dancing Script', cursive;
    
    --font-size-xs: 0.75rem;    /* 12px */
    --font-size-sm: 0.875rem;   /* 14px */
    --font-size-base: 1rem;     /* 16px */
    --font-size-lg: 1.125rem;   /* 18px */
    --font-size-xl: 1.25rem;    /* 20px */
    --font-size-2xl: 1.5rem;    /* 24px */
    --font-size-3xl: 1.875rem;  /* 30px */
    --font-size-4xl: 2.25rem;   /* 36px */
    --font-size-5xl: 3rem;      /* 48px */
    --font-size-6xl: 3.75rem;   /* 60px */
    
    --font-weight-light: 300;
    --font-weight-normal: 400;
    --font-weight-medium: 500;
    --font-weight-semibold: 600;
    --font-weight-bold: 700;
    
    --line-height-tight: 1.25;
    --line-height-normal: 1.5;
    --line-height-relaxed: 1.75;
    
    /* Spacing */
    --space-1: 0.25rem;   /* 4px */
    --space-2: 0.5rem;    /* 8px */
    --space-3: 0.75rem;   /* 12px */
    --space-4: 1rem;      /* 16px */
    --space-5: 1.25rem;   /* 20px */
    --space-6: 1.5rem;    /* 24px */
    --space-8: 2rem;      /* 32px */
    --space-10: 2.5rem;   /* 40px */
    --space-12: 3rem;     /* 48px */
    --space-16: 4rem;     /* 64px */
    --space-20: 5rem;     /* 80px */
    --space-24: 6rem;     /* 96px */
    --space-32: 8rem;     /* 128px */
    
    /* Layout */
    --container-max-width: 1200px;
    --container-padding: var(--space-6);
    
    --header-height: 80px;
    --section-padding: var(--space-20);
    
    /* Border Radius */
    --radius-sm: 0.25rem;   /* 4px */
    --radius-md: 0.5rem;    /* 8px */
    --radius-lg: 0.75rem;   /* 12px */
    --radius-xl: 1rem;      /* 16px */
    --radius-2xl: 1.5rem;   /* 24px */
    --radius-full: 9999px;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    --shadow-2xl: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
    
    /* Transitions */
    --transition-fast: 150ms ease-in-out;
    --transition-normal: 250ms ease-in-out;
    --transition-slow: 350ms ease-in-out;
    
    /* Z-index */
    --z-dropdown: 1000;
    --z-sticky: 1020;
    --z-fixed: 1030;
    --z-modal-backdrop: 1040;
    --z-modal: 1050;
    --z-popover: 1060;
    --z-tooltip: 1070;
    --z-toast: 1080;
    
    /* Breakpoints (for reference in media queries) */
    --breakpoint-sm: 640px;
    --breakpoint-md: 768px;
    --breakpoint-lg: 1024px;
    --breakpoint-xl: 1280px;
    --breakpoint-2xl: 1536px;
}

/* Dark mode variables */
[data-theme="dark"] {
    --bg-primary: var(--gray-900);
    --bg-secondary: var(--gray-800);
    --bg-tertiary: var(--gray-700);
    --bg-overlay: rgba(0, 0, 0, 0.8);
    
    --text-primary: var(--white);
    --text-secondary: var(--gray-300);
    --text-tertiary: var(--gray-400);
    --text-inverse: var(--gray-900);
    
    --border-primary: var(--gray-700);
    --border-secondary: var(--gray-600);
    
    /* Dark mode specific shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4), 0 2px 4px -1px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.4), 0 4px 6px -2px rgba(0, 0, 0, 0.3);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.4), 0 10px 10px -5px rgba(0, 0, 0, 0.3);
}

/* Dark mode specific styling for "Giving Lab Equipment a Second Life" */
[data-theme="dark"] .about-text h3 {
    color: var(--primary-teal) !important;
}

/* Dark mode navigation improvements */
[data-theme="dark"] .nav-brand {
    color: var(--primary-teal) !important;
}

[data-theme="dark"] .nav-title {
    color: var(--primary-teal) !important;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
    text-decoration: none;
}

[data-theme="dark"] .nav-title:hover {
    color: var(--primary-teal-bright) !important;
    text-shadow: 0 4px 8px rgba(0, 0, 0, 0.4);
    text-decoration: none;
}

[data-theme="dark"] .nav-title:visited {
    color: var(--primary-teal) !important;
}

[data-theme="dark"] .nav-link {
    color: var(--primary-teal) !important;
}

[data-theme="dark"] .nav-link:hover,
[data-theme="dark"] .nav-link.active {
    color: #1A5F5F !important; /* Dark blue for hover */
}

/* Fallback for system preference */
@media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) {
        --bg-primary: var(--gray-900);
        --bg-secondary: var(--gray-800);
        --bg-tertiary: var(--gray-700);
        --bg-overlay: rgba(0, 0, 0, 0.8);
        
        --text-primary: var(--white);
        --text-secondary: var(--gray-300);
        --text-tertiary: var(--gray-400);
        --text-inverse: var(--gray-900);
        
        --border-primary: var(--gray-700);
        --border-secondary: var(--gray-600);
        
        --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
        --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4), 0 2px 4px -1px rgba(0, 0, 0, 0.3);
        --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.4), 0 4px 6px -2px rgba(0, 0, 0, 0.3);
        --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.4), 0 10px 10px -5px rgba(0, 0, 0, 0.3);
        --shadow-2xl: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
    }
    
    /* System preference fallback for "Giving Lab Equipment a Second Life" */
    .about-text h3 {
        color: var(--primary-teal) !important;
    }
    
    /* System preference fallback for navigation */
    .nav-brand {
        color: var(--primary-teal) !important;
    }
    
    .nav-title {
        color: var(--primary-teal) !important;
        text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
        text-decoration: none;
    }
    
    .nav-title:hover {
        color: var(--primary-teal-bright) !important;
        text-shadow: 0 4px 8px rgba(0, 0, 0, 0.4);
        text-decoration: none;
    }
    
    .nav-title:visited {
        color: var(--primary-teal) !important;
    }
    
    .nav-link {
        color: var(--primary-teal) !important;
    }
    
    .nav-link:hover,
    .nav-link.active {
        color: #1A5F5F !important; /* Dark blue for hover */
    }
}

/* Reduced motion preferences */
@media (prefers-reduced-motion: reduce) {
    :root {
        --transition-fast: 0ms;
        --transition-normal: 0ms;
        --transition-slow: 0ms;
    }
    
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}