/**
 * Modern Design System - Tamil Arasan Website
 * A contemporary design framework with dark mode support
 */

/* ===== DESIGN TOKENS ===== */
:root {
  /* Modern Color Palette - Light Mode */
  --color-primary: #4F46E5;
  --color-primary-light: #818CF8;
  --color-primary-dark: #3730A3;
  
  --color-secondary: #EC4899;
  --color-secondary-light: #F472B6;
  --color-secondary-dark: #BE185D;
  
  --color-accent: #06B6D4;
  --color-accent-light: #22D3EE;
  --color-accent-dark: #0891B2;
  
  --color-success: #10B981;
  --color-warning: #F59E0B;
  --color-error: #EF4444;
  
  /* Neutral Colors */
  --color-bg: #FFFFFF;
  --color-bg-secondary: #F9FAFB;
  --color-bg-tertiary: #F3F4F6;
  --color-surface: #FFFFFF;
  --color-surface-elevated: #FFFFFF;
  
  --color-text: #111827;
  --color-text-secondary: #6B7280;
  --color-text-tertiary: #9CA3AF;
  
  --color-border: #E5E7EB;
  --color-border-light: #F3F4F6;
  
  /* Gradients */
  --gradient-primary: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  --gradient-secondary: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
  --gradient-accent: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
  --gradient-sunset: linear-gradient(135deg, #fa709a 0%, #fee140 100%);
  --gradient-ocean: linear-gradient(135deg, #a8edea 0%, #fed6e3 100%);
  --gradient-hero: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  
  /* Typography Scale */
  --font-family-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Inter', 'Helvetica Neue', Arial, sans-serif;
  --font-family-serif: 'Playfair Display', 'Georgia', serif;
  --font-family-mono: 'SF Mono', 'Monaco', 'Cascadia Code', 'Courier New', monospace;
  
  --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;
  --font-weight-extrabold: 800;
  
  --line-height-tight: 1.25;
  --line-height-snug: 1.375;
  --line-height-normal: 1.5;
  --line-height-relaxed: 1.625;
  --line-height-loose: 2;
  
  /* Spacing Scale */
  --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 */
  
  /* Border Radius */
  --radius-sm: 0.375rem;   /* 6px */
  --radius-md: 0.5rem;     /* 8px */
  --radius-lg: 0.75rem;    /* 12px */
  --radius-xl: 1rem;       /* 16px */
  --radius-2xl: 1.5rem;    /* 24px */
  --radius-full: 9999px;
  
  /* Shadows - Modern, Subtle */
  --shadow-xs: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-sm: 0 1px 3px 0 rgb(0 0 0 / 0.1), 0 1px 2px -1px rgb(0 0 0 / 0.1);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
  --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);
  --shadow-2xl: 0 25px 50px -12px rgb(0 0 0 / 0.25);
  --shadow-inner: inset 0 2px 4px 0 rgb(0 0 0 / 0.05);
  
  /* 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);
  --transition-bounce: 500ms cubic-bezier(0.68, -0.55, 0.265, 1.55);
  
  /* Z-Index Scale */
  --z-base: 1;
  --z-dropdown: 1000;
  --z-sticky: 1020;
  --z-fixed: 1030;
  --z-modal-backdrop: 1040;
  --z-modal: 1050;
  --z-popover: 1060;
  --z-tooltip: 1070;
  
  /* Blur Effects */
  --blur-sm: 4px;
  --blur-md: 8px;
  --blur-lg: 16px;
  --blur-xl: 24px;
}

/* Dark Mode Colors */
[data-theme="dark"] {
  --color-primary: #818CF8;
  --color-primary-light: #A5B4FC;
  --color-primary-dark: #6366F1;
  
  --color-secondary: #F472B6;
  --color-secondary-light: #F9A8D4;
  --color-secondary-dark: #EC4899;
  
  --color-accent: #22D3EE;
  --color-accent-light: #67E8F9;
  --color-accent-dark: #06B6D4;
  
  --color-bg: #0F172A;
  --color-bg-secondary: #1E293B;
  --color-bg-tertiary: #334155;
  --color-surface: #1E293B;
  --color-surface-elevated: #334155;
  
  --color-text: #F1F5F9;
  --color-text-secondary: #CBD5E1;
  --color-text-tertiary: #94A3B8;
  
  --color-border: #334155;
  --color-border-light: #475569;
  
  /* Dark mode shadows */
  --shadow-xs: 0 1px 2px 0 rgb(0 0 0 / 0.3);
  --shadow-sm: 0 1px 3px 0 rgb(0 0 0 / 0.4), 0 1px 2px -1px rgb(0 0 0 / 0.4);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.4), 0 2px 4px -2px rgb(0 0 0 / 0.4);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.4), 0 4px 6px -4px rgb(0 0 0 / 0.4);
  --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.5), 0 8px 10px -6px rgb(0 0 0 / 0.5);
  --shadow-2xl: 0 25px 50px -12px rgb(0 0 0 / 0.6);
}

/* ===== BASE STYLES ===== */
* {
  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-family-sans);
  font-size: var(--font-size-base);
  font-weight: var(--font-weight-normal);
  line-height: var(--line-height-relaxed);
  color: var(--color-text);
  background-color: var(--color-bg);
  transition: background-color var(--transition-base), color var(--transition-base);
}

/* ===== TYPOGRAPHY ===== */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-family-serif);
  font-weight: var(--font-weight-bold);
  line-height: var(--line-height-tight);
  color: var(--color-text);
  margin-bottom: var(--space-4);
}

h1 { font-size: var(--font-size-5xl); }
h2 { font-size: var(--font-size-4xl); }
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(--space-4);
  color: var(--color-text-secondary);
}

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

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

strong, b {
  font-weight: var(--font-weight-semibold);
}

/* ===== MODERN NAVBAR ===== */
.navbar-modern {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: var(--z-sticky);
  background: rgba(255, 255, 255, 0.8);
  backdrop-filter: blur(var(--blur-lg));
  -webkit-backdrop-filter: blur(var(--blur-lg));
  border-bottom: 1px solid var(--color-border-light);
  padding: var(--space-4) 0;
  transition: all var(--transition-base);
}

[data-theme="dark"] .navbar-modern {
  background: rgba(15, 23, 42, 0.8);
  border-bottom-color: var(--color-border);
}

.navbar-modern.scrolled {
  box-shadow: var(--shadow-md);
  padding: var(--space-3) 0;
}

.navbar-container {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 var(--space-6);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.navbar-brand-modern {
  font-family: var(--font-family-serif);
  font-size: var(--font-size-2xl);
  font-weight: var(--font-weight-bold);
  color: var(--color-text);
  transition: color var(--transition-fast);
}

.navbar-brand-modern:hover {
  color: var(--color-primary);
}

.navbar-nav-modern {
  display: flex;
  gap: var(--space-2);
  align-items: center;
  list-style: none;
}

.nav-link-modern {
  position: relative;
  padding: var(--space-2) var(--space-4);
  font-weight: var(--font-weight-medium);
  color: var(--color-text-secondary);
  border-radius: var(--radius-lg);
  transition: all var(--transition-fast);
}

.nav-link-modern:hover {
  color: var(--color-text);
  background: var(--color-bg-tertiary);
}

.nav-link-modern.active {
  color: var(--color-primary);
  background: rgba(79, 70, 229, 0.1);
}

[data-theme="dark"] .nav-link-modern.active {
  background: rgba(129, 140, 248, 0.1);
}

/* Mobile Menu Toggle */
.navbar-toggler-modern {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--space-2);
  color: var(--color-text);
  font-size: var(--font-size-2xl);
}

/* Dark Mode Toggle */
.theme-toggle {
  background: var(--color-bg-tertiary);
  border: none;
  border-radius: var(--radius-full);
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all var(--transition-fast);
  color: var(--color-text);
  margin-left: var(--space-2);
}

.theme-toggle:hover {
  background: var(--color-border);
  transform: scale(1.05);
}

/* ===== HERO SECTION ===== */
.hero-modern {
  min-height: 90vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--gradient-hero);
  position: relative;
  overflow: hidden;
  padding: var(--space-20) var(--space-6);
  margin-top: 70px;
}

.hero-modern::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: 
    radial-gradient(circle at 20% 50%, rgba(255, 255, 255, 0.1) 0%, transparent 50%),
    radial-gradient(circle at 80% 80%, rgba(255, 255, 255, 0.1) 0%, transparent 50%);
  pointer-events: none;
}

.hero-container {
  max-width: 1280px;
  margin: 0 auto;
  position: relative;
  z-index: 1;
}

.hero-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-16);
  align-items: center;
}

.hero-text {
  color: white;
}

.hero-title {
  font-size: var(--font-size-6xl);
  font-weight: var(--font-weight-extrabold);
  color: white;
  margin-bottom: var(--space-6);
  line-height: 1.1;
}

.hero-subtitle {
  font-size: var(--font-size-2xl);
  color: rgba(255, 255, 255, 0.9);
  margin-bottom: var(--space-8);
  font-weight: var(--font-weight-medium);
}

.hero-description {
  font-size: var(--font-size-lg);
  color: rgba(255, 255, 255, 0.8);
  margin-bottom: var(--space-8);
  line-height: var(--line-height-relaxed);
}

.hero-cta {
  display: flex;
  gap: var(--space-4);
  flex-wrap: wrap;
}

.hero-image-container {
  position: relative;
}

.hero-image {
  width: 100%;
  max-width: 500px;
  height: auto;
  border-radius: var(--radius-2xl);
  box-shadow: var(--shadow-2xl);
  border: 4px solid rgba(255, 255, 255, 0.2);
  transition: transform var(--transition-slow);
}

.hero-image:hover {
  transform: scale(1.02) rotate(-1deg);
}

/* ===== BUTTONS ===== */
.btn-modern {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-6);
  font-size: var(--font-size-base);
  font-weight: var(--font-weight-semibold);
  border-radius: var(--radius-lg);
  border: none;
  cursor: pointer;
  transition: all var(--transition-fast);
  text-decoration: none;
  white-space: nowrap;
}

.btn-primary {
  background: white;
  color: var(--color-primary);
}

.btn-primary:hover {
  background: rgba(255, 255, 255, 0.9);
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

.btn-secondary {
  background: var(--color-bg);
  color: var(--color-text);
  border: 2px solid var(--color-text-secondary);
  font-weight: var(--font-weight-semibold);
}

.btn-secondary:hover {
  background: var(--color-bg-secondary);
  border-color: var(--color-primary);
  color: var(--color-primary);
  transform: translateY(-2px);
}

.btn-outline {
  background: transparent;
  color: var(--color-text);
  border: 2px solid var(--color-border);
}

.btn-outline:hover {
  background: var(--color-bg-tertiary);
  border-color: var(--color-primary);
  color: var(--color-primary);
}

/* ===== CARDS ===== */
.card-modern {
  background: var(--color-surface);
  border-radius: var(--radius-xl);
  padding: var(--space-6);
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--color-border-light);
  transition: all var(--transition-base);
}

.card-modern:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-4px);
}

.card-header-modern {
  margin-bottom: var(--space-4);
}

.card-title-modern {
  font-size: var(--font-size-2xl);
  margin-bottom: var(--space-2);
}

.card-description-modern {
  color: var(--color-text-secondary);
  font-size: var(--font-size-base);
}

/* ===== SECTIONS ===== */
.section-modern {
  padding: var(--space-20) var(--space-6);
}

.section-container {
  max-width: 1280px;
  margin: 0 auto;
}

.section-header {
  text-align: center;
  margin-bottom: var(--space-16);
}

.section-title-modern {
  font-size: var(--font-size-4xl);
  margin-bottom: var(--space-4);
  position: relative;
  display: inline-block;
}

.section-title-modern::after {
  content: '';
  position: absolute;
  bottom: -8px;
  left: 50%;
  transform: translateX(-50%);
  width: 60px;
  height: 4px;
  background: var(--gradient-primary);
  border-radius: var(--radius-full);
}

.section-description {
  font-size: var(--font-size-lg);
  color: var(--color-text-secondary);
  max-width: 700px;
  margin: 0 auto;
}

/* ===== GRID LAYOUTS ===== */
.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-8);
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-8);
}

.grid-4 {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-6);
}

/* ===== FOOTER ===== */
.footer-modern {
  background: var(--color-bg-secondary);
  border-top: 1px solid var(--color-border);
  padding: var(--space-16) var(--space-6) var(--space-8);
  margin-top: var(--space-20);
}

.footer-container {
  max-width: 1280px;
  margin: 0 auto;
}

.footer-content {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: var(--space-12);
  margin-bottom: var(--space-12);
}

.footer-brand {
  font-family: var(--font-family-serif);
  font-size: var(--font-size-2xl);
  font-weight: var(--font-weight-bold);
  color: var(--color-text);
  margin-bottom: var(--space-4);
}

.footer-description {
  color: var(--color-text-secondary);
  margin-bottom: var(--space-6);
}

.footer-section-title {
  font-size: var(--font-size-lg);
  font-weight: var(--font-weight-semibold);
  margin-bottom: var(--space-4);
}

.footer-links {
  list-style: none;
}

.footer-link {
  display: block;
  color: var(--color-text-secondary);
  padding: var(--space-2) 0;
  transition: color var(--transition-fast);
}

.footer-link:hover {
  color: var(--color-primary);
  padding-left: var(--space-2);
}

.footer-bottom {
  padding-top: var(--space-8);
  border-top: 1px solid var(--color-border);
  display: flex;
  justify-content: space-between;
  align-items: center;
  color: var(--color-text-tertiary);
  font-size: var(--font-size-sm);
}

/* ===== SOCIAL LINKS ===== */
.social-links-modern {
  display: flex;
  gap: var(--space-3);
}

.social-link-modern {
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-full);
  background: var(--color-bg-tertiary);
  color: var(--color-text);
  font-size: var(--font-size-lg);
  transition: all var(--transition-fast);
}

.social-link-modern:hover {
  background: var(--color-primary);
  color: white;
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
}

/* ===== RESPONSIVE ===== */
@media (max-width: 1024px) {
  :root {
    --font-size-6xl: 3rem;
    --font-size-5xl: 2.5rem;
    --font-size-4xl: 2rem;
  }
  
  .hero-content {
    grid-template-columns: 1fr;
    gap: var(--space-12);
    text-align: center;
  }
  
  .hero-image {
    margin: 0 auto;
  }
  
  .hero-cta {
    justify-content: center;
  }
  
  .grid-3 {
    grid-template-columns: repeat(2, 1fr);
  }
  
  .grid-4 {
    grid-template-columns: repeat(2, 1fr);
  }
  
  .footer-content {
    grid-template-columns: 1fr;
    gap: var(--space-8);
  }
}

@media (max-width: 768px) {
  :root {
    --space-20: 3rem;
    --space-16: 2.5rem;
  }
  
  .navbar-nav-modern {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--color-surface);
    flex-direction: column;
    padding: var(--space-4);
    box-shadow: var(--shadow-lg);
    border-radius: 0 0 var(--radius-lg) var(--radius-lg);
  }
  
  .navbar-nav-modern.show {
    display: flex;
  }
  
  .navbar-toggler-modern {
    display: block;
  }
  
  .hero-title {
    font-size: var(--font-size-4xl);
  }
  
  .hero-subtitle {
    font-size: var(--font-size-xl);
  }
  
  .grid-2,
  .grid-3,
  .grid-4 {
    grid-template-columns: 1fr;
  }
  
  .section-title-modern {
    font-size: var(--font-size-3xl);
  }
  
  .footer-bottom {
    flex-direction: column;
    gap: var(--space-4);
    text-align: center;
  }
}

/* ===== UTILITY CLASSES ===== */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.mt-0 { margin-top: 0; }
.mt-4 { margin-top: var(--space-4); }
.mt-8 { margin-top: var(--space-8); }
.mt-12 { margin-top: var(--space-12); }
.mb-0 { margin-bottom: 0; }
.mb-4 { margin-bottom: var(--space-4); }
.mb-8 { margin-bottom: var(--space-8); }
.mb-12 { margin-bottom: var(--space-12); }

.container-modern {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 var(--space-6);
}

/* ===== ANIMATIONS ===== */
@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.fade-in {
  animation: fadeIn 0.6s ease-out;
}

@keyframes slideIn {
  from {
    opacity: 0;
    transform: translateX(-30px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

.slide-in {
  animation: slideIn 0.6s ease-out;
}

/* ===== SMOOTH SCROLLING ===== */
html.smooth-scroll {
  scroll-behavior: smooth;
}

/* ===== FOCUS STYLES ===== */
*:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

/* ===== SELECTION ===== */
::selection {
  background: var(--color-primary);
  color: white;
}

/* ===== BOOTSTRAP NAVBAR DARK MODE ===== */
/* Make navbar-toggler icon white everywhere - all specificity levels */
.navbar-toggler-icon,
.navbar-light .navbar-toggler-icon,
.navbar .navbar-toggler-icon,
button.navbar-toggler .navbar-toggler-icon {
  background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 30 30'%3e%3cpath stroke='rgba(255, 255, 255, 1)' stroke-linecap='round' stroke-miterlimit='10' stroke-width='2' d='M4 7h22M4 15h22M4 23h22'/%3e%3c/svg%3e") !important;
}

/* White hamburger in dark mode with even higher specificity */
[data-theme="dark"] .navbar-toggler-icon,
[data-theme="dark"] .navbar-light .navbar-toggler-icon,
[data-theme="dark"] .navbar .navbar-toggler-icon {
  background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 30 30'%3e%3cpath stroke='rgba(255, 255, 255, 1)' stroke-linecap='round' stroke-miterlimit='10' stroke-width='2' d='M4 7h22M4 15h22M4 23h22'/%3e%3c/svg%3e") !important;
}

/* Border styling */
.navbar-toggler,
[data-theme="dark"] .navbar-toggler,
[data-theme="dark"] .navbar-light .navbar-toggler {
  border-color: rgba(255, 255, 255, 0.3) !important;
}

/* Hide theme toggle completely on blog and notes pages via CSS as backup */
body[data-page*="blog"] .theme-toggle,
body[data-page*="blog"] .fab.theme-toggle,
body[data-page*="note"] .theme-toggle,
body[data-page*="note"] .fab.theme-toggle {
  display: none !important;
}

/* ===== MATHJAX STYLING ===== */
/* MathJax equations use default styling */
/* Dark mode is disabled on blog/notes pages for equation compatibility */

mjx-container {
  background: transparent;
}