/* Core Color Palette */
:root {
  /* Base Colors */
  --color-black: #0a0a0a;
  --color-black-soft: #1a1a1a;
  --color-black-mute: #252525;
  --color-white: #ffffff;
  --color-white-soft: #f8f8f8;
  --color-gray: #888888;
  --color-gray-light: #aaaaaa;
  --color-gray-dark: #444444;

  /* Brand Colors - Black & White Theme */
  --color-primary: #ffffff;
  --color-primary-dark: #cccccc;
  --color-primary-light: #ffffff;
  --color-accent: #ffffff;
  --color-accent-dark: #cccccc;

  /* Semantic Colors */
  --color-background: #000000;
  --color-background-elevated: #1a1a1a;
  --color-background-card: rgba(255, 255, 255, 0.03);
  --color-surface: rgba(255, 255, 255, 0.05);
  --color-text-primary: #ffffff;
  --color-text-secondary: rgba(255, 255, 255, 0.7);
  --color-text-tertiary: rgba(255, 255, 255, 0.5);

  /* Border & Divider Colors */
  --color-border: rgba(255, 255, 255, 0.15);
  --color-border-hover: rgba(255, 255, 255, 0.4);
  --color-divider: rgba(255, 255, 255, 0.1);

  /* Gradient Colors - Grayscale */
  --gradient-primary: linear-gradient(135deg, #ffffff 0%, #cccccc 100%);
  --gradient-accent: linear-gradient(135deg, #ffffff 0%, #aaaaaa 100%);
  --gradient-mesh: radial-gradient(at 0% 0%, rgba(255, 255, 255, 0.02) 0px, transparent 50%),
                   radial-gradient(at 100% 100%, rgba(255, 255, 255, 0.02) 0px, transparent 50%);

  /* Spacing System (8px base) */
  --space-xs: 0.25rem;   /* 4px */
  --space-sm: 0.5rem;    /* 8px */
  --space-md: 1rem;      /* 16px */
  --space-lg: 1.5rem;    /* 24px */
  --space-xl: 2rem;      /* 32px */
  --space-2xl: 3rem;     /* 48px */
  --space-3xl: 4rem;     /* 64px */
  --space-4xl: 6rem;     /* 96px */
  --space-5xl: 8rem;     /* 128px */

  /* Typography Scale */
  --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 */

  /* Line Heights */
  --line-height-tight: 1.2;
  --line-height-normal: 1.5;
  --line-height-relaxed: 1.75;
  --line-height-loose: 2;

  /* Font Weights */
  --font-weight-normal: 400;
  --font-weight-medium: 500;
  --font-weight-semibold: 600;
  --font-weight-bold: 700;

  /* 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-glow: 0 0 15px rgba(255, 255, 255, 0.2);
  --shadow-glow-accent: 0 0 15px rgba(255, 255, 255, 0.2);

  /* Transitions */
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-base: 250ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 350ms cubic-bezier(0.4, 0, 0.2, 1);

  /* Z-index Scale */
  --z-base: 0;
  --z-dropdown: 1000;
  --z-sticky: 1100;
  --z-fixed: 1200;
  --z-modal: 1300;
  --z-popover: 1400;
  --z-tooltip: 1500;

  /* Container Widths */
  --container-sm: 640px;
  --container-md: 768px;
  --container-lg: 1024px;
  --container-xl: 1280px;
  --container-2xl: 1400px;

  /* Section Gaps */
  --section-gap: 8rem;
  --section-gap-mobile: 4rem;
}

/* Reset & Base Styles */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

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

body {
  min-height: 100vh;
  background: var(--color-background);
  background-image: var(--gradient-mesh);
  background-attachment: fixed;
  background-size: 100% 100vh;
  color: var(--color-text-primary);
  font-family: 'Share Tech', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  font-size: var(--font-size-lg);
  line-height: var(--line-height-relaxed);
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Viewport edge fade effect */
body::before,
body::after {
  content: '';
  position: fixed;
  left: 0;
  right: 0;
  height: 40px;
  pointer-events: none;
  z-index: 9999;
  filter: blur(4px);
}

body::before {
  top: -5px;
  background: linear-gradient(to bottom,
    rgba(0, 0, 0, 0.65) 0%,
    rgba(0, 0, 0, 0.58) 8%,
    rgba(0, 0, 0, 0.50) 16%,
    rgba(0, 0, 0, 0.42) 24%,
    rgba(0, 0, 0, 0.35) 32%,
    rgba(0, 0, 0, 0.28) 40%,
    rgba(0, 0, 0, 0.22) 48%,
    rgba(0, 0, 0, 0.16) 56%,
    rgba(0, 0, 0, 0.11) 64%,
    rgba(0, 0, 0, 0.07) 72%,
    rgba(0, 0, 0, 0.04) 80%,
    rgba(0, 0, 0, 0.02) 88%,
    transparent 100%);
}

body::after {
  bottom: -5px;
  background: linear-gradient(to top,
    rgba(0, 0, 0, 0.65) 0%,
    rgba(0, 0, 0, 0.58) 8%,
    rgba(0, 0, 0, 0.50) 16%,
    rgba(0, 0, 0, 0.42) 24%,
    rgba(0, 0, 0, 0.35) 32%,
    rgba(0, 0, 0, 0.28) 40%,
    rgba(0, 0, 0, 0.22) 48%,
    rgba(0, 0, 0, 0.16) 56%,
    rgba(0, 0, 0, 0.11) 64%,
    rgba(0, 0, 0, 0.07) 72%,
    rgba(0, 0, 0, 0.04) 80%,
    rgba(0, 0, 0, 0.02) 88%,
    transparent 100%);
}

/* Selection */
::selection {
  background: var(--color-primary);
  color: var(--color-black);
}

::-moz-selection {
  background: var(--color-primary);
  color: var(--color-black);
}

/* Scrollbar Styling */
::-webkit-scrollbar {
  width: 12px;
}

::-webkit-scrollbar-track {
  background: var(--color-black-soft);
}

::-webkit-scrollbar-thumb {
  background: var(--color-primary);
  border-radius: var(--radius-full);
  border: 3px solid var(--color-black-soft);
}

::-webkit-scrollbar-thumb:hover {
  background: var(--color-primary-light);
}

/* Enhanced Focus Styles for Accessibility */
:focus {
  outline: none;
}

:focus-visible {
  outline: 3px solid var(--color-primary);
  outline-offset: 3px;
  border-radius: var(--radius-sm);
}

/* Specific focus styles for interactive elements */
button:focus-visible,
a:focus-visible,
input:focus-visible,
textarea:focus-visible,
select:focus-visible {
  outline: 3px solid var(--color-primary);
  outline-offset: 3px;
  box-shadow: 0 0 0 4px rgba(255, 255, 255, 0.1);
}

/* Focus for dark mode contrast */
.category-button:focus-visible,
.back-to-top:focus-visible {
  outline: 3px solid var(--color-primary);
  outline-offset: 2px;
  box-shadow: 0 0 15px rgba(255, 255, 255, 0.4);
}

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