/* ============================================
   Personal Portfolio Website - Main Styles
   Core layout, typography, and base styles
   ============================================ */

/* ============================================
   CSS Custom Properties (Theming Variables)
   ============================================ */
:root {
  /* Color Palette - Modern Gradient Theme */
  --primary-color: #6366f1;
  --primary-light: #818cf8;
  --primary-dark: #4f46e5;
  --secondary-color: #8b5cf6;
  --accent-color: #06b6d4;
  --bg-dark: #0f172a;
  --bg-darker: #020617;
  --bg-card: #1e293b;
  --text-primary: #f8fafc;
  --text-secondary: #cbd5e1;
  --text-muted: #64748b;
  --accent-glow: rgba(99, 102, 241, 0.3);
  
  /* Spacing System (8px base unit) */
  --spacing-unit: 8px;
  --spacing-xs: calc(var(--spacing-unit) * 1);   /* 8px */
  --spacing-sm: calc(var(--spacing-unit) * 2);   /* 16px */
  --spacing-md: calc(var(--spacing-unit) * 3);   /* 24px */
  --spacing-lg: calc(var(--spacing-unit) * 4);   /* 32px */
  --spacing-xl: calc(var(--spacing-unit) * 6);   /* 48px */
  --spacing-2xl: calc(var(--spacing-unit) * 10); /* 80px */
  
  /* Typography */
  --font-primary: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Helvetica Neue', Arial, sans-serif;
  --font-mono: 'Fira Code', 'Courier New', monospace;
  
  /* Font Sizes */
  --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 */
  
  /* Line Heights */
  --line-height-tight: 1.25;
  --line-height-normal: 1.5;
  --line-height-relaxed: 1.75;
  
  /* Border Radius */
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 16px;
  
  /* Transitions */
  --transition-fast: 0.15s ease;
  --transition-base: 0.3s ease;
  --transition-slow: 0.6s ease;
  
  /* Z-index Layers */
  --z-base: 1;
  --z-dropdown: 10;
  --z-sticky: 100;
  --z-modal: 1000;
  
  /* Container Widths */
  --container-max-width: 1200px;
  --container-padding: var(--spacing-md);
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-primary);
  font-size: var(--font-size-base);
  line-height: var(--line-height-normal);
  color: var(--text-primary);
  background-color: var(--bg-dark);
  min-width: 320px;
  overflow-x: hidden;
}

/* ============================================
   Typography
   ============================================ */
h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: var(--line-height-tight);
  margin-bottom: var(--spacing-md);
  color: var(--text-primary);
}

h1 {
  font-size: var(--font-size-5xl);
  letter-spacing: -0.02em;
}

h2 {
  font-size: var(--font-size-4xl);
  letter-spacing: -0.01em;
}

h3 {
  font-size: var(--font-size-3xl);
}

h4 {
  font-size: var(--font-size-2xl);
}

h5 {
  font-size: var(--font-size-xl);
}

h6 {
  font-size: var(--font-size-lg);
}

p {
  margin-bottom: var(--spacing-md);
  color: var(--text-secondary);
  line-height: var(--line-height-relaxed);
}

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

a:hover {
  color: var(--text-primary);
}

a:focus {
  outline: 2px solid var(--primary-color);
  outline-offset: 2px;
}

strong, b {
  font-weight: 600;
  color: var(--text-primary);
}

em, i {
  font-style: italic;
}

code {
  font-family: var(--font-mono);
  font-size: 0.9em;
  padding: 0.2em 0.4em;
  background-color: rgba(255, 255, 255, 0.05);
  border-radius: var(--radius-sm);
}

/* ============================================
   Layout Utilities
   ============================================ */
.container {
  max-width: var(--container-max-width);
  margin: 0 auto;
  padding-left: var(--container-padding);
  padding-right: var(--container-padding);
  width: 100%;
}

section {
  min-height: 100vh;
  padding: var(--spacing-2xl) 0;
  position: relative;
}

/* Section Spacing Variations */
section.compact {
  min-height: auto;
  padding: var(--spacing-xl) 0;
}

section.full-height {
  min-height: 100vh;
  display: flex;
  align-items: center;
}

/* ============================================
   Grid System
   ============================================ */
.grid {
  display: grid;
  gap: var(--spacing-lg);
}

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

.grid-cols-2 {
  grid-template-columns: repeat(2, 1fr);
}

.grid-cols-3 {
  grid-template-columns: repeat(3, 1fr);
}

.grid-cols-4 {
  grid-template-columns: repeat(4, 1fr);
}

/* Auto-fit responsive grid */
.grid-auto-fit {
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
}

/* ============================================
   Flexbox Utilities
   ============================================ */
.flex {
  display: flex;
}

.flex-col {
  flex-direction: column;
}

.flex-wrap {
  flex-wrap: wrap;
}

.items-center {
  align-items: center;
}

.items-start {
  align-items: flex-start;
}

.items-end {
  align-items: flex-end;
}

.justify-center {
  justify-content: center;
}

.justify-between {
  justify-content: space-between;
}

.justify-start {
  justify-content: flex-start;
}

.justify-end {
  justify-content: flex-end;
}

.gap-xs { gap: var(--spacing-xs); }
.gap-sm { gap: var(--spacing-sm); }
.gap-md { gap: var(--spacing-md); }
.gap-lg { gap: var(--spacing-lg); }
.gap-xl { gap: var(--spacing-xl); }

/* ============================================
   Spacing Utilities
   ============================================ */
.m-0 { margin: 0; }
.mt-xs { margin-top: var(--spacing-xs); }
.mt-sm { margin-top: var(--spacing-sm); }
.mt-md { margin-top: var(--spacing-md); }
.mt-lg { margin-top: var(--spacing-lg); }
.mt-xl { margin-top: var(--spacing-xl); }

.mb-xs { margin-bottom: var(--spacing-xs); }
.mb-sm { margin-bottom: var(--spacing-sm); }
.mb-md { margin-bottom: var(--spacing-md); }
.mb-lg { margin-bottom: var(--spacing-lg); }
.mb-xl { margin-bottom: var(--spacing-xl); }

.p-0 { padding: 0; }
.pt-xs { padding-top: var(--spacing-xs); }
.pt-sm { padding-top: var(--spacing-sm); }
.pt-md { padding-top: var(--spacing-md); }
.pt-lg { padding-top: var(--spacing-lg); }
.pt-xl { padding-top: var(--spacing-xl); }

.pb-xs { padding-bottom: var(--spacing-xs); }
.pb-sm { padding-bottom: var(--spacing-sm); }
.pb-md { padding-bottom: var(--spacing-md); }
.pb-lg { padding-bottom: var(--spacing-lg); }
.pb-xl { padding-bottom: var(--spacing-xl); }

/* ============================================
   Text Utilities
   ============================================ */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.text-primary { color: var(--text-primary); }
.text-secondary { color: var(--text-secondary); }
.text-accent { color: var(--primary-color); }

.text-xs { font-size: var(--font-size-xs); }
.text-sm { font-size: var(--font-size-sm); }
.text-base { font-size: var(--font-size-base); }
.text-lg { font-size: var(--font-size-lg); }
.text-xl { font-size: var(--font-size-xl); }
.text-2xl { font-size: var(--font-size-2xl); }
.text-3xl { font-size: var(--font-size-3xl); }
.text-4xl { font-size: var(--font-size-4xl); }
.text-5xl { font-size: var(--font-size-5xl); }

.font-normal { font-weight: 400; }
.font-medium { font-weight: 500; }
.font-semibold { font-weight: 600; }
.font-bold { font-weight: 700; }

.uppercase { text-transform: uppercase; }
.lowercase { text-transform: lowercase; }
.capitalize { text-transform: capitalize; }

.tracking-tight { letter-spacing: -0.02em; }
.tracking-normal { letter-spacing: 0; }
.tracking-wide { letter-spacing: 0.05em; }

/* ============================================
   Button Base Styles
   ============================================ */
button {
  font-family: inherit;
  font-size: inherit;
  cursor: pointer;
  border: none;
  background: none;
  padding: 0;
  color: inherit;
}

button:focus {
  outline: 2px solid var(--primary-color);
  outline-offset: 2px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: var(--spacing-sm) var(--spacing-lg);
  font-size: var(--font-size-base);
  font-weight: 600;
  border-radius: var(--radius-md);
  transition: all var(--transition-base);
  cursor: pointer;
  text-decoration: none;
  border: 1px solid transparent;
  min-height: 44px; /* Touch-friendly */
  min-width: 44px;
}

.btn-primary {
  background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
  color: white;
  border-color: transparent;
  font-weight: 600;
  box-shadow: 0 4px 6px -1px rgba(99, 102, 241, 0.3);
}

.btn-primary:hover {
  background: linear-gradient(135deg, var(--primary-light), var(--primary-color));
  transform: translateY(-2px);
  box-shadow: 0 10px 15px -3px rgba(99, 102, 241, 0.4);
}

.btn-secondary {
  background-color: transparent;
  color: var(--text-primary);
  border-color: rgba(255, 255, 255, 0.2);
}

.btn-secondary:hover {
  border-color: var(--primary-color);
  color: var(--primary-color);
}

/* ============================================
   List Styles
   ============================================ */
ul, ol {
  list-style: none;
}

ul.styled-list,
ol.styled-list {
  list-style-position: inside;
  padding-left: var(--spacing-md);
}

ul.styled-list {
  list-style-type: disc;
}

ol.styled-list {
  list-style-type: decimal;
}

li {
  margin-bottom: var(--spacing-sm);
  color: var(--text-secondary);
}

/* ============================================
   Image Styles
   ============================================ */
img {
  max-width: 100%;
  height: auto;
  display: block;
}

img[loading="lazy"] {
  opacity: 0;
  transition: opacity var(--transition-slow);
}

img[loading="lazy"].loaded {
  opacity: 1;
}

/* ============================================
   Accessibility
   ============================================ */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border-width: 0;
}

/* Skip to main content link */
.skip-link {
  position: absolute;
  top: -40px;
  left: 0;
  background: var(--primary-color);
  color: var(--bg-dark);
  padding: var(--spacing-sm) var(--spacing-md);
  text-decoration: none;
  z-index: var(--z-modal);
  font-weight: 600;
}

.skip-link:focus {
  top: 0;
}

/* Focus visible for keyboard navigation */
:focus-visible {
  outline: 2px solid var(--primary-color);
  outline-offset: 2px;
}

/* ============================================
   Reduced Motion Support
   ============================================ */
@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;
  }
}

/* ============================================
   Print Styles
   ============================================ */
@media print {
  body {
    background: white;
    color: black;
  }
  
  a {
    text-decoration: underline;
  }
  
  a[href^="http"]::after {
    content: " (" attr(href) ")";
  }
  
  section {
    page-break-inside: avoid;
  }
}