/* Base styles and variables */
:root {
  /* Color palette */
  --primary-50: #EFF6FF;
  --primary-100: #DBEAFE;
  --primary-200: #BFDBFE;
  --primary-300: #93C5FD;
  --primary-400: #60A5FA;
  --primary-500: #3B82F6;
  --primary-600: #2563EB;
  --primary-700: #1D4ED8;
  --primary-800: #1E40AF;
  --primary-900: #1E3A8A;
  
  --accent-500: #F97316;
  --accent-600: #EA580C;
  
  --success-500: #10B981;
  --warning-500: #FBBF24;
  --error-500: #EF4444;
  
  --neutral-50: #F9FAFB;
  --neutral-100: #F3F4F6;
  --neutral-200: #E5E7EB;
  --neutral-300: #D1D5DB;
  --neutral-400: #9CA3AF;
  --neutral-500: #6B7280;
  --neutral-600: #4B5563;
  --neutral-700: #374151;
  --neutral-800: #1F2937;
  --neutral-900: #111827;
  
  /* Typography */
  --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  
  /* Spacing based on 8px system */
  --space-1: 0.5rem;  /* 8px */
  --space-2: 1rem;    /* 16px */
  --space-3: 1.5rem;  /* 24px */
  --space-4: 2rem;    /* 32px */
  --space-5: 2.5rem;  /* 40px */
  --space-6: 3rem;    /* 48px */
  
  /* Border radius */
  --radius-sm: 0.25rem; /* 4px */
  --radius-md: 0.5rem;  /* 8px */
  --radius-lg: 1rem;    /* 16px */
  
  /* 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);
  
  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-normal: 300ms ease;
  
  /* Light theme default */
  --bg-primary: var(--neutral-50);
  --bg-secondary: white;
  --bg-tertiary: var(--neutral-100);
  --text-primary: var(--neutral-900);
  --text-secondary: var(--neutral-700);
  --text-tertiary: var(--neutral-500);
  --border-color: var(--neutral-200);

  /* Chatbot specific variables */
  --chat-primary: var(--primary-600);
  --chat-bg: var(--bg-secondary);
  --chat-text: var(--text-primary);
  --chat-border: var(--border-color);
  --chat-shadow: var(--shadow-lg);
  --chat-radius: var(--radius-md);
}

/* Dark theme */
[data-theme="dark"] {
  --bg-primary: var(--neutral-900);
  --bg-secondary: var(--neutral-800);
  --bg-tertiary: var(--neutral-700);
  --text-primary: var(--neutral-50);
  --text-secondary: var(--neutral-300);
  --text-tertiary: var(--neutral-400);
  --border-color: var(--neutral-700);
}

/* General Reset */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: var(--font-family);
  line-height: 1.5;
  color: var(--text-primary);
  background-color: var(--bg-primary);
  transition: background-color var(--transition-normal), color var(--transition-normal);
}

h1, h2, h3, h4, h5, h6 {
  line-height: 1.2;
  margin-bottom: var(--space-2);
  font-weight: 600;
}

p {
  margin-bottom: var(--space-2);
}

a {
  color: var(--primary-600);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--primary-800);
}

button {
  cursor: pointer;
  border: none;
  background: none;
  font-family: inherit;
  transition: all var(--transition-fast);
}

ul, ol {
  list-style-position: inside;
  margin-bottom: var(--space-2);
}

/* App container */
.app-container {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Header styles */
header {
  background-color: var(--bg-secondary);
  box-shadow: var(--shadow-sm);
  position: sticky;
  top: 0;
  z-index: 100;
  border-bottom: 1px solid var(--border-color);
}

.header-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--space-2);
  max-width: 1440px;
  margin: 0 auto;
  width: 100%;
}

.logo h1 {
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 0;
}

.logo span {
  color: var(--primary-600);
}

.search-container {
  display: flex;
  flex-grow: 1;
  max-width: 500px;
  margin: 0 var(--space-3);
}

.search-container input {
  width: 100%;
  padding: var(--space-1) var(--space-2);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  background-color: var(--bg-tertiary);
  color: var(--text-primary);
  font-size: 0.875rem;
}

.search-container button {
  margin-left: -2.5rem;
  color: var(--text-tertiary);
  padding: var(--space-1);
}

.header-actions {
  display: flex;
  gap: var(--space-2);
}

.header-actions button {
  color: var(--text-secondary);
  padding: var(--space-1);
  border-radius: var(--radius-md);
}

.header-actions button:hover {
  color: var(--primary-600);
  background-color: var(--bg-tertiary);
}

/* Main content */
main {
  flex-grow: 1;
  max-width: 1440px;
  margin: 0 auto;
  width: 100%;
  padding: var(--space-2);
}

/* Hero section */
.hero-section {
  background: linear-gradient(135deg, var(--primary-700), var(--primary-500));
  color: white;
  border-radius: var(--radius-md);
  padding: var(--space-5) var(--space-3);
  margin-bottom: var(--space-4);
  text-align: center;
  box-shadow: var(--shadow-md);
}

.hero-content h2 {
  font-size: 2.5rem;
  margin-bottom: var(--space-1);
  font-weight: 700;
}

.hero-content p {
  font-size: 1.25rem;
  opacity: 0.9;
}

/* Subjects section */
.section-title {
  margin-bottom: var(--space-3);
  font-size: 1.5rem;
  position: relative;
  display: inline-block;
}

.section-title::after {
  content: '';
  position: absolute;
  bottom: -5px;
  left: 0;
  width: 40px;
  height: 3px;
  background-color: var(--primary-600);
  border-radius: 3px;
}

.subjects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--space-3);
}

.subject-card {
  background-color: var(--bg-secondary);
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
  overflow: hidden;
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
  box-shadow: var(--shadow-sm);
  height: 100%;
  display: flex;
  flex-direction: column;
}

.subject-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-md);
}

.subject-card-img {
  height: 160px;
  overflow: hidden;
}

.subject-card-img img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform var(--transition-normal);
}

.subject-card:hover .subject-card-img img {
  transform: scale(1.05);
}

.subject-card-content {
  padding: var(--space-2);
  flex-grow: 1;
  display: flex;
  flex-direction: column;
}

.subject-card h3 {
  font-size: 1.25rem;
  margin-bottom: var(--space-1);
}

.subject-card p {
  color: var(--text-secondary);
  font-size: 0.875rem;
  margin-bottom: var(--space-2);
  flex-grow: 1;
}

.subject-card-meta {
  display: flex;
  justify-content: space-between;
  font-size: 0.75rem;
  color: var(--text-tertiary);
}

.subject-card-button {
  background-color: var(--primary-600);
  color: white;
  border-radius: var(--radius-md);
  padding: var(--space-1) var(--space-2);
  font-weight: 500;
  text-align: center;
  margin-top: var(--space-1);
  transition: background-color var(--transition-fast);
}

.subject-card-button:hover {
  background-color: var(--primary-700);
}

/* Subject view styles */
.subject-container {
  display: flex;
  height: calc(100vh - 64px); /* Adjust based on header height */
  border-radius: var(--radius-md);
  overflow: hidden;
  background-color: var(--bg-secondary);
  box-shadow: var(--shadow-md);
  border: 1px solid var(--border-color);
}

.sidebar {
  width: 300px;
  background-color: var(--bg-tertiary);
  border-right: 1px solid var(--border-color);
  display: flex;
  flex-direction: column;
  transition: transform var(--transition-normal);
}

.sidebar-header {
  padding: var(--space-2);
  border-bottom: 1px solid var(--border-color);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.sidebar-header h2 {
  margin-bottom: 0;
  font-size: 1.25rem;
}

.mobile-close-sidebar {
  display: none;
}

.topic-search {
  padding: var(--space-2);
  border-bottom: 1px solid var(--border-color);
}

.topic-search input {
  width: 100%;
  padding: var(--space-1);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  background-color: var(--bg-secondary);
  color: var(--text-primary);
  font-size: 0.875rem;
}

.topics-nav {
  flex-grow: 1;
  overflow-y: auto;
}

.topics-nav ul {
  list-style: none;
  margin: 0;
}

.topics-nav li {
  border-bottom: 1px solid var(--border-color);
}

.topics-nav a {
  display: block;
  padding: var(--space-2);
  color: var(--text-secondary);
  transition: background-color var(--transition-fast), color var(--transition-fast);
}

.topics-nav a:hover, .topics-nav a.active {
  background-color: var(--bg-secondary);
  color: var(--primary-600);
}

.topics-nav a.completed {
  position: relative;
}

.topics-nav a.completed::after {
  content: '\f058';
  font-family: 'Font Awesome 6 Free';
  font-weight: 900;
  position: absolute;
  right: var(--space-2);
  color: var(--success-500);
}

.content-area {
  flex-grow: 1;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.content-header {
  padding: var(--space-2);
  border-bottom: 1px solid var(--border-color);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.mobile-toggle-sidebar {
  display: none;
}

.topic-path {
  color: var(--text-secondary);
  font-size: 0.875rem;
}

.topic-path span:last-child {
  color: var(--text-primary);
  font-weight: 500;
}

.content-actions {
  display: flex;
  gap: var(--space-1);
}

.content-actions button {
  color: var(--text-secondary);
  padding: var(--space-1);
  border-radius: var(--radius-md);
}

.content-actions button:hover {
  color: var(--primary-600);
  background-color: var(--bg-tertiary);
}

.topic-content {
  padding: var(--space-3);
  overflow-y: auto;
  flex-grow: 1;
}

.topic-content h1 {
  font-size: 2rem;
  margin-bottom: var(--space-3);
  position: relative;
}

.topic-content h1::after {
  content: '';
  position: absolute;
  bottom: -10px;
  left: 0;
  width: 60px;
  height: 4px;
  background-color: var(--primary-600);
  border-radius: 4px;
}

.topic-content h2 {
  font-size: 1.5rem;
  margin-top: var(--space-4);
  margin-bottom: var(--space-2);
  color: var(--text-secondary);
}

.topic-content h3 {
  font-size: 1.25rem;
  margin-top: var(--space-3);
  margin-bottom: var(--space-1);
}

.topic-content p {
  margin-bottom: var(--space-2);
  line-height: 1.6;
}

.topic-content ul, .topic-content ol {
  margin-left: var(--space-3);
  margin-bottom: var(--space-3);
}

.topic-content img {
  max-width: 100%;
  border-radius: var(--radius-md);
  margin: var(--space-3) 0;
}

.topic-content pre {
  background-color: var(--bg-tertiary);
  padding: var(--space-2);
  border-radius: var(--radius-md);
  overflow-x: auto;
  margin: var(--space-2) 0;
}

.topic-content blockquote {
  border-left: 4px solid var(--primary-400);
  padding-left: var(--space-2);
  margin: var(--space-3) 0;
  color: var(--text-secondary);
}

.topic-content table {
  width: 100%;
  border-collapse: collapse;
  margin: var(--space-3) 0;
}

.topic-content th, .topic-content td {
  padding: var(--space-1) var(--space-2);
  border: 1px solid var(--border-color);
}

.topic-content th {
  background-color: var(--bg-tertiary);
  text-align: left;
}

/* Footer */
footer {
  background-color: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  padding: var(--space-4) var(--space-2);
  margin-top: var(--space-4);
}

.footer-container {
  max-width: 1440px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: var(--space-4);
}

.footer-section h3 {
  font-size: 1.25rem;
  margin-bottom: var(--space-2);
}

.footer-section p {
  color: var(--text-secondary);
}

.footer-section ul {
  list-style: none;
  margin: 0;
  padding: 0;
}

.footer-section ul li {
  margin-bottom: var(--space-1);
}

.social-icons {
  display: flex;
  gap: var(--space-2);
  margin-top: var(--space-1);
}

.social-icons a {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background-color: var(--bg-tertiary);
  color: var(--text-secondary);
  transition: background-color var(--transition-fast), color var(--transition-fast);
}

.social-icons a:hover {
  background-color: var(--primary-600);
  color: white;
}

.footer-bottom {
  max-width: 1440px;
  margin: 0 auto;
  text-align: center;
  padding-top: var(--space-3);
  margin-top: var(--space-3);
  border-top: 1px solid var(--border-color);
  color: var(--text-tertiary);
  font-size: 0.875rem;
}

/* Animations */
@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes slideInUp {
  from {
    transform: translateY(20px);
    opacity: 0;
  }
  to {
    transform: translateY(0);
    opacity: 1;
  }
}

.subject-card {
  animation: fadeIn 0.5s ease forwards;
}

.topic-content {
  animation: fadeIn 0.3s ease forwards;
}

/* Loading spinner */
.loading {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100%;
  animation: fadeIn 0.3s ease forwards;
}

.loading-spinner {
  width: 40px;
  height: 40px;
  border: 4px solid var(--border-color);
  border-top: 4px solid var(--primary-600);
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

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

/* Chatbot styles */
.chat-container {
  position: fixed;
  bottom: 20px;
  right: 20px;
  z-index: 1000;
}

.chat-toggle {
  width: 60px;
  height: 60px;
  border-radius: 50%;
  background-color: var(--chat-primary);
  color: white;
  border: none;
  cursor: pointer;
  box-shadow: var(--chat-shadow);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 24px;
  transition: transform var(--transition-fast);
}

.chat-toggle:hover {
  transform: scale(1.1);
}

.chat-box {
  position: absolute;
  bottom: 80px;
  right: 0;
  width: 350px;
  height: 500px;
  background-color: var(--chat-bg);
  border-radius: var(--chat-radius);
  box-shadow: var(--chat-shadow);
  display: none;
  flex-direction: column;
  overflow: hidden;
  border: 1px solid var(--chat-border);
}

.chat-box.active {
  display: flex;
}

.chat-header {
  padding: 15px;
  background-color: var(--chat-primary);
  color: white;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.chat-header h3 {
  margin: 0;
  font-size: 1.1rem;
}

.minimize-chat {
  background: none;
  border: none;
  color: white;
  cursor: pointer;
  padding: 5px;
}

.chat-messages {
  flex-grow: 1;
  padding: 15px;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.message {
  max-width: 80%;
  padding: 10px 15px;
  border-radius: var(--chat-radius);
  font-size: 0.9rem;
  line-height: 1.4;
}

.message.user {
  background-color: var(--chat-primary);
  color: white;
  align-self: flex-end;
}

.message.bot {
  background-color: var(--bg-tertiary);
  color: var(--chat-text);
  align-self: flex-start;
}

.message.typing::after {
  content: '';
  animation: typing 1s infinite;
}

@keyframes typing {
  0% { content: '.'; }
  33% { content: '..'; }
  66% { content: '...'; }
}

.chat-input {
  padding: 15px;
  display: flex;
  gap: 10px;
  border-top: 1px solid var(--chat-border);
}

.chat-input input {
  flex-grow: 1;
  padding: 10px;
  border: 1px solid var(--chat-border);
  border-radius: var(--chat-radius);
  background-color: var(--bg-tertiary);
  color: var(--chat-text);
}

.chat-input button {
  padding: 10px 15px;
  background-color: var(--chat-primary);
  color: white;
  border: none;
  border-radius: var(--chat-radius);
  cursor: pointer;
  transition: background-color var(--transition-fast);
}

.chat-input button:hover {
  background-color: var(--primary-700);
}