/* ------------------------------------ */
/* CSS Variables for Multi-Color Theming */
/* ------------------------------------ */
:root {
  /* Fonts */
  --font-primary: 'Inter', sans-serif;
  --font-secondary: 'Poppins', sans-serif;
  
  /* Light Theme Colors */
  --bg-color-light: #ffffff;
  --text-color-light: #2c3e50;
  --header-bg-light: #f5f8fa;
  --sidebar-bg-light: #f5f8fa;
  --card-bg-light: #ffffff;
  --accent-color-light: #3498db;
  --border-color-light: #e0e6ed;
  --shadow-color-light: rgba(0, 0, 0, 0.08);
  --table-header-bg-light: #ecf0f1;
  --theme-toggle-bg-light: #bdc3c7;
  --theme-toggle-slider-light: #ffffff;
  --theme-sun-color-light: #f1c40f;
  --theme-moon-color-light: #7f8c8d;
  
  /* Dark Theme Colors */
  --bg-color-dark: #1f2937;
  --text-color-dark: #e5e7eb;
  --header-bg-dark: #111827;
  --sidebar-bg-dark: #111827;
  --card-bg-dark: #1f2937;
  --accent-color-dark: #3b82f6;
  --border-color-dark: #374151;
  --shadow-color-dark: rgba(0, 0, 0, 0.25);
  --table-header-bg-dark: #374151;
  --theme-toggle-bg-dark: #4b5563;
  --theme-toggle-slider-dark: #ffffff;
  --theme-sun-color-dark: #fde047;
  --theme-moon-color-dark: #9ca3af;
  
  /* Cosmic Theme Colors */
  --bg-color-cosmic: #0a0f18;
  --text-color-cosmic: #e5e7eb;
  --header-bg-cosmic: #151b24;
  --sidebar-bg-cosmic: #151b24;
  --card-bg-cosmic: #1e293b;
  --accent-color-cosmic: #6366f1;
  --border-color-cosmic: #334155;
  --shadow-color-cosmic: rgba(0, 0, 0, 0.4);
  --table-header-bg-cosmic: #1f2937;
  --theme-toggle-bg-cosmic: #334155;
  --theme-toggle-slider-cosmic: #9333ea;
  --theme-sun-color-cosmic: #fde047;
  --theme-moon-color-cosmic: #a5b4fc;
  
  /* Multi-color gradients for headers and special elements */
  --gradient-gold: linear-gradient(45deg, #f9a825, #fbc02d);
  --gradient-blue-purple: linear-gradient(45deg, #3b82f6, #9333ea);
  --gradient-teal-pink: linear-gradient(45deg, #14b8a6, #ec4899);
  
  /* Spacing Variables */
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-2xl: 3rem;
  
  /* Border Radius */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  
  /* Shadows */
  --shadow-sm: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
  --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);
}

/* ------------------------------------ */
/* Global Base Styles */
/* ------------------------------------ */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

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

body {
  font-family: var(--font-primary);
  background: var(--bg-color-dark);
  color: var(--text-color-dark);
  line-height: 1.6;
  transition: background-color 0.3s, color 0.3s;
  min-height: 100vh;
}

/* ------------------------------------ */
/* Theme Switching Logic */
/* ------------------------------------ */
body.light-mode {
  --bg-color-dark: var(--bg-color-light);
  --text-color-dark: var(--text-color-light);
  --header-bg-dark: var(--header-bg-light);
  --sidebar-bg-dark: var(--sidebar-bg-light);
  --card-bg-dark: var(--card-bg-light);
  --accent-color-dark: var(--accent-color-light);
  --border-color-dark: var(--border-color-light);
  --shadow-color-dark: var(--shadow-color-light);
  --table-header-bg-dark: var(--table-header-bg-light);
  --theme-toggle-bg-dark: var(--theme-toggle-bg-light);
  --theme-toggle-slider-dark: var(--theme-toggle-slider-light);
  --theme-sun-color-dark: var(--theme-sun-color-light);
  --theme-moon-color-dark: var(--theme-moon-color-light);
}

body.cosmic-mode {
  --bg-color-dark: var(--bg-color-cosmic);
  --text-color-dark: var(--text-color-cosmic);
  --header-bg-dark: var(--header-bg-cosmic);
  --sidebar-bg-dark: var(--sidebar-bg-cosmic);
  --card-bg-dark: var(--card-bg-cosmic);
  --accent-color-dark: var(--accent-color-cosmic);
  --border-color-dark: var(--border-color-cosmic);
  --shadow-color-dark: var(--shadow-color-cosmic);
  --table-header-bg-dark: var(--table-header-bg-cosmic);
  --theme-toggle-bg-dark: var(--theme-toggle-bg-cosmic);
  --theme-toggle-slider-dark: var(--theme-toggle-slider-cosmic);
  --theme-sun-color-dark: var(--theme-sun-color-cosmic);
  --theme-moon-color-dark: var(--theme-moon-color-cosmic);
}

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

@keyframes spin {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}

/* ------------------------------------ */
/* Layout Components */
/* ------------------------------------ */
.page-container {
  display: grid;
  grid-template-columns: 280px 1fr;
  grid-template-rows: auto 1fr;
  grid-template-areas:
      "header header"
      "sidebar content";
  min-height: 100vh;
  max-width: 100%;
  overflow-x: hidden;
  background-color: var(--bg-color-dark);
  transition: background-color 0.3s ease;
}

/* Header */
header {
  grid-area: header;
  background-color: var(--header-bg-dark);
  padding: var(--spacing-md) var(--spacing-2xl);
  border-bottom: 1px solid var(--border-color-dark);
  box-shadow: var(--shadow-xl);
  display: flex;
  justify-content: space-between;
  align-items: center;
  position: sticky;
  top: 0;
  z-index: 1000;
  transition: background-color 0.3s ease;
}

/* Sidebar */
.sidebar {
  grid-area: sidebar;
  background-color: var(--sidebar-bg-dark);
  padding: var(--spacing-xl);
  border-right: 1px solid var(--border-color-dark);
  position: sticky;
  top: 75px;
  height: calc(100vh - 75px);
  overflow-y: auto;
  transition: background-color 0.3s ease;
}

.sidebar h2 {
  margin-top: 0;
  font-size: 1.5rem;
  color: var(--accent-color-dark);
  border-bottom: 2px solid var(--accent-color-dark);
  padding-bottom: var(--spacing-sm);
}

.sidebar ul {
  list-style: none;
  padding: 0;
}

.sidebar li {
  margin-bottom: var(--spacing-md);
}

.sidebar li a {
  display: block;
  padding: var(--spacing-sm) var(--spacing-md);
  color: var(--text-color-dark);
  font-weight: 500;
  border-left: 3px solid transparent;
  text-decoration: none;
  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  border-radius: var(--radius-sm);
}

.sidebar li a:hover {
  color: var(--accent-color-dark);
  background-color: rgba(var(--accent-color-dark), 0.1);
  border-left: 3px solid var(--accent-color-dark);
  transform: translateX(5px);
}

/* Main Content */
.content {
  grid-area: content;
  padding: var(--spacing-2xl) var(--spacing-2xl);
  max-width: 100%;
  overflow-x: hidden;
  animation: fadeIn 0.8s ease-in-out;
}

/* ------------------------------------ */
/* Component Styles */
/* ------------------------------------ */

/* Cards */
.card {
  background-color: var(--card-bg-dark);
  border: 1px solid var(--border-color-dark);
  border-radius: var(--radius-lg);
  padding: var(--spacing-lg);
  margin-top: var(--spacing-xl);
  box-shadow: var(--shadow-lg);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.card:hover {
  transform: translateY(-8px);
  box-shadow: 0 15px 25px -5px var(--shadow-color-dark), 0 5px 10px -5px var(--shadow-color-dark);
}

.card.formula {
  background-color: var(--sidebar-bg-dark);
  border-left: 5px solid var(--accent-color-dark);
  font-family: monospace;
  font-size: 1.1rem;
}

.card ul, .card ol {
  padding-left: var(--spacing-xl);
}

.card-container {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--spacing-xl);
  margin-top: var(--spacing-md);
}

/* Tables */
table {
  width: 100%;
  border-collapse: collapse;
  margin-top: var(--spacing-lg);
  overflow: hidden;
  border-radius: var(--radius-md);
}

th, td {
  text-align: left;
  padding: var(--spacing-md);
  border-bottom: 1px solid var(--border-color-dark);
}

th {
  background-color: var(--table-header-bg-dark);
  font-weight: 600;
  white-space: nowrap;
}

tbody tr:hover {
  background-color: rgba(59, 130, 246, 0.1);
}

/* Links */
a {
  color: var(--accent-color-dark);
  text-decoration: none;
  transition: color 0.2s;
}

a:hover {
  text-decoration: underline;
  filter: brightness(1.2);
}

/* Headings */
h1, h2, h3, h4 {
  color: var(--text-color-dark);
  font-weight: 700;
  line-height: 1.3;
}

h1 { 
  font-size: 3rem; 
  text-align: center;
  margin-bottom: var(--spacing-xl);
  background: var(--gradient-blue-purple);
  background-clip: text;
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

h2 { 
  font-size: 2.25rem; 
  border-bottom: 2px solid var(--border-color-dark); 
  padding-bottom: var(--spacing-md); 
  margin-top: var(--spacing-2xl); 
  margin-bottom: var(--spacing-lg);
  color: var(--accent-color-dark);
}

h3 { 
  font-size: 1.75rem; 
  margin-top: var(--spacing-xl); 
  margin-bottom: var(--spacing-md); 
}

h4 { 
  font-size: 1.5rem; 
  margin-top: var(--spacing-lg);
  margin-bottom: var(--spacing-sm);
}

/* Text Elements */
p, li {
  font-size: 1.1rem;
  margin-bottom: var(--spacing-md);
  color: var(--text-color-dark);
}

b, strong {
  color: var(--accent-color-dark);
  font-weight: 600;
}

code {
  background-color: rgba(59, 130, 246, 0.1);
  padding: 2px 6px;
  border-radius: var(--radius-sm);
  font-family: monospace;
  color: var(--accent-color-dark);
}

/* Theme Toggle */
.theme-toggle-checkbox {
  display: none;
}

.theme-toggle-label {
  background: var(--theme-toggle-bg-dark);
  border-radius: 50px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 5px;
  position: relative;
  height: 28px;
  width: 60px;
  transition: background-color 0.3s ease;
}

.theme-toggle-label .sun, .theme-toggle-label .moon {
  font-size: 16px;
  line-height: 1;
  transition: color 0.3s ease;
}

.theme-toggle-label .sun { color: var(--theme-sun-color-dark); }
.theme-toggle-label .moon { color: var(--theme-moon-color-dark); }

.theme-toggle-label::after {
  content: '';
  position: absolute;
  top: 4px;
  left: 4px;
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background-color: var(--theme-toggle-slider-dark);
  transition: transform 0.3s ease, background-color 0.3s ease;
}

.theme-toggle-checkbox:checked + .theme-toggle-label::after {
  transform: translateX(32px);
}

/* ------------------------------------ */
/* Responsive Design (Mobile First) */
/* ------------------------------------ */

/* Mobile & Small Mobile */
@media (max-width: 768px) {
  .page-container {
    grid-template-columns: 1fr;
    grid-template-areas:
        "header"
        "content";
  }
  
  .sidebar {
    display: none; /* Hide sidebar on mobile */
  }
  
  header {
    flex-direction: column;
    gap: var(--spacing-md);
    padding: var(--spacing-md);
  }
  
  .content {
    padding: var(--spacing-lg);
    overflow-x: hidden;
    word-wrap: break-word;
  }
  
  h1 { font-size: 2rem; }
  h2 { font-size: 1.5rem; }
  h3 { font-size: 1.25rem; }
  h4 { font-size: 1.125rem; }
  p, li { 
    font-size: 1rem; 
    word-wrap: break-word;
    overflow-wrap: break-word;
  }
  
  .card-container {
    grid-template-columns: 1fr;
  }
  
  .subject-card h2 { font-size: 1.5rem; }
  .class-card { padding: var(--spacing-lg); }
  
  /* Fix text overflow */
  * {
    max-width: 100%;
    box-sizing: border-box;
  }
  
  table {
    font-size: 0.875rem;
    overflow-x: auto;
    display: block;
    white-space: nowrap;
  }
  
  th, td {
    padding: 0.5rem;
    min-width: 100px;
  }
  
  /* MathJax responsive */
  .MathJax {
    font-size: 0.9em !important;
  }
  
  /* Code blocks */
  code {
    font-size: 0.875rem;
    word-break: break-all;
  }
}

/* Tablet */
@media (min-width: 769px) and (max-width: 1024px) {
  .page-container {
    grid-template-columns: 200px 1fr;
  }
  
  .content {
    padding: var(--spacing-xl);
  }
  
  h1 { font-size: 2.5rem; }
  h2 { font-size: 1.75rem; }
  
  .subject-card h2 { font-size: 1.75rem; }
}

/* Very Small Mobile */
@media (max-width: 480px) {
  .content {
    padding: var(--spacing-md);
  }
  
  h1 { font-size: 1.5rem; }
  h2 { font-size: 1.25rem; }
  h3 { font-size: 1.125rem; }
  h4 { font-size: 1rem; }
  p, li { font-size: 0.875rem; }
  
  table {
    font-size: 0.75rem;
  }
  
  th, td {
    padding: 0.25rem;
    min-width: 60px;
  }
  
  .MathJax {
    font-size: 0.8em !important;
  }
  
  code {
    font-size: 0.75rem;
  }
}

/* Desktop */
@media (min-width: 1025px) {
  .page-container {
    grid-template-columns: 280px 1fr;
  }
  
  .content {
    padding: var(--spacing-2xl);
  }
  
  h1 { font-size: 3rem; }
  h2 { font-size: 2.25rem; }
}