/* ===== CSS Custom Properties ===== */
:root {
  --primary-blue: #1976d2;
  --primary-teal: #00796b;
  --accent-blue: #0984e3;
  --accent-teal: #00cec9;
  --text-dark: #2d3436;
  --text-medium: #34495e;
  --text-light: #666;
  --bg-white: #ffffff;
  --bg-light: #f4f4f9;
  --bg-card: #f8f9ff;
  --border-light: #dee2e6;
  --shadow-light: rgba(0, 0, 0, 0.05);
  --shadow-medium: rgba(0, 0, 0, 0.1);
  --shadow-dark: rgba(0, 0, 0, 0.2);
  
  /* Mobile-first spacing */
  --spacing-xs: 0.5rem;
  --spacing-sm: 1rem;
  --spacing-md: 1.5rem;
  --spacing-lg: 2rem;
  --spacing-xl: 3rem;
  
  /* Typography scale */
  --font-size-sm: clamp(0.875rem, 2vw, 1rem);
  --font-size-base: clamp(1rem, 2.5vw, 1.125rem);
  --font-size-lg: clamp(1.25rem, 3vw, 1.5rem);
  --font-size-xl: clamp(1.5rem, 4vw, 2rem);
  --font-size-2xl: clamp(2rem, 5vw, 2.8rem);
}

/* ===== Reset and Base Styles ===== */
* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: 'Poppins', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  margin: 0;
  padding: 0;
  padding-bottom: 60px;
  background-color: var(--bg-light);
  color: var(--text-dark);
  overflow-x: hidden;
  line-height: 1.6;
  font-size: var(--font-size-base);
  
  /* Mobile-optimized background */
  background-image: url('https://images.unsplash.com/photo-1732287931034-c4cc1b06de6a?q=80&w=2787&auto=format&fit=crop&ixlib=rb-4.0.3&ixid=M3wxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8fA%3D%3D');
  background-size: cover;
  background-position: center;
  background-attachment: fixed;
  background-repeat: no-repeat;
}

/* Disable background attachment on mobile for better performance */
@media (max-width: 768px) {
  body {
    background-attachment: scroll;
    background-size: cover;
  }
}

/* ===== Header ===== */
header {
  background: linear-gradient(135deg, var(--primary-teal), var(--primary-blue));
  padding: var(--spacing-lg) var(--spacing-sm);
  box-shadow: 0 4px 20px var(--shadow-medium);
  position: relative;
  overflow: hidden;
}

header h1 {
  text-align: center;
  font-size: var(--font-size-2xl);
  color: var(--bg-white);
  margin: 0;
  font-family: 'Poppins', sans-serif;
  font-weight: 600;
  letter-spacing: -0.5px;
  text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
  word-wrap: break-word;
  hyphens: auto;
}

header h1::after {
  content: "";
  display: block;
  width: min(120px, 80%);
  height: 4px;
  background: rgba(255, 255, 255, 0.8);
  margin: var(--spacing-sm) auto;
  border-radius: 2px;
  transform: scaleX(0);
  transition: transform 0.3s ease;
}

header:hover h1::after {
  transform: scaleX(1);
}

/* ===== Navigation Bar ===== */
.main-navbar {
  background: linear-gradient(to right, var(--primary-blue), var(--primary-teal));
  box-shadow: 0 4px 12px var(--shadow-medium);
  font-family: 'Poppins', sans-serif;
  position: sticky;
  top: 0;
  z-index: 1000;
  overflow: visible;
}

/* Mobile hamburger button */
.mobile-menu-toggle {
  display: none;
  flex-direction: column;
  background: transparent;
  border: none;
  padding: var(--spacing-sm);
  cursor: pointer;
  position: absolute;
  right: var(--spacing-sm);
  top: 50%;
  transform: translateY(-50%);
  z-index: 1002;
}

.hamburger-line {
  width: 25px;
  height: 3px;
  background-color: var(--bg-white);
  margin: 3px 0;
  transition: all 0.3s ease;
  transform-origin: center;
}

.mobile-menu-toggle.active .hamburger-line:nth-child(1) {
  transform: rotate(45deg) translate(6px, 6px);
}

.mobile-menu-toggle.active .hamburger-line:nth-child(2) {
  opacity: 0;
}

.mobile-menu-toggle.active .hamburger-line:nth-child(3) {
  transform: rotate(-45deg) translate(6px, -6px);
}

/* Navigation links */
.nav-links {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  justify-content: center;
  gap: var(--spacing-md);
  position: relative;
}

.nav-links > li {
  position: relative;
}

.nav-links a {
  display: block;
  padding: var(--spacing-sm) var(--spacing-md);
  color: var(--bg-white);
  text-decoration: none;
  font-weight: 600;
  transition: all 0.3s ease;
  border-radius: 6px;
  font-size: var(--font-size-sm);
  white-space: nowrap;
  min-height: 44px; /* Touch-friendly minimum */
  display: flex;
  align-items: center;
}

.nav-links > li:hover > a {
  background-color: var(--bg-white);
  color: var(--text-dark);
}

/* Desktop dropdown */
.dropdown {
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  background: var(--bg-white);
  min-width: 220px;
  border-radius: 8px;
  box-shadow: 0 8px 25px var(--shadow-medium);
  padding: var(--spacing-xs) 0;
  z-index: 1001;
}

.dropdown li {
  margin: 0;
}

.dropdown a {
  color: var(--text-dark);
  font-weight: 500;
  padding: var(--spacing-sm) var(--spacing-md);
  border-radius: 0;
  font-size: var(--font-size-sm);
}

.dropdown a:hover {
  background-color: #f1f1f1;
  color: var(--primary-blue);
}

/* Desktop dropdown reveal */
.nav-links li:hover .dropdown {
  display: block;
}

/* Mobile menu overlay */
.mobile-menu-overlay {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.5);
  z-index: 999;
}

/* ===== Mobile Navigation Styles ===== */
@media (max-width: 768px) {
  .mobile-menu-toggle {
    display: flex;
  }
  
  .nav-links {
    position: fixed;
    top: 0;
    right: -100%;
    width: 80%;
    max-width: 300px;
    height: 100vh;
    background: var(--bg-white);
    flex-direction: column;
    justify-content: flex-start;
    align-items: stretch;
    padding: 80px 0 var(--spacing-lg);
    gap: 0;
    transition: right 0.3s ease;
    overflow-y: auto;
    box-shadow: -5px 0 15px var(--shadow-medium);
    z-index: 1001;
  }
  
  .nav-links.mobile-open {
    right: 0;
  }
  
  .mobile-menu-active .mobile-menu-overlay {
    display: block;
  }
  
  .nav-links > li {
    width: 100%;
    border-bottom: 1px solid #f0f0f0;
  }
  
  .nav-links a {
    color: var(--text-dark);
    padding: var(--spacing-md) var(--spacing-lg);
    font-weight: 500;
    justify-content: space-between;
    min-height: 48px;
    white-space: normal;
  }
  
  .nav-links > li > a::after {
    content: '▼';
    font-size: 0.8em;
    transition: transform 0.3s ease;
    opacity: 0.6;
  }
  
  .nav-links > li:last-child > a::after {
    content: '▼';
  }
  
  .nav-links > li.dropdown-open > a::after {
    transform: rotate(180deg);
  }
  
  .dropdown {
    position: static;
    display: none;
    box-shadow: none;
    background: #f8f9fa;
    border-radius: 0;
    padding: 0;
    margin: 0;
    width: 100%;
  }
  
  .dropdown-open .dropdown {
    display: block;
  }
  
  .dropdown a {
    padding: var(--spacing-sm) calc(var(--spacing-lg) + var(--spacing-md));
    font-size: 0.9em;
    color: var(--text-medium);
    border-bottom: 1px solid #e9ecef;
  }
  
  .dropdown a:hover {
    background-color: #e9ecef;
    color: var(--primary-blue);
  }
}

/* ===== Main Content ===== */
main {
  padding: var(--spacing-sm);
  margin: var(--spacing-sm) auto;
  max-width: 1200px;
  border: 2px solid #ccc;
  border-radius: 10px;
  background-color: rgba(255, 255, 255, 0.95);
  box-shadow: 0 4px 8px var(--shadow-medium);
  overflow-y: auto;
}

@media (min-width: 769px) {
  main {
    padding: var(--spacing-lg);
    margin: var(--spacing-lg) auto;
  }
}

/* ===== Content Wrapper ===== */
.content-wrapper {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-lg);
  width: 100%;
}

/* ===== Content Boxes ===== */
.content-box {
  background: var(--bg-white);
  border-radius: 16px;
  padding: var(--spacing-md);
  margin-bottom: var(--spacing-lg);
  box-shadow: 0 8px 30px var(--shadow-light);
  border-left: 0;
  transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1), box-shadow 0.3s ease;
  position: relative;
  overflow: hidden;
  width: 100%;
}

@media (min-width: 769px) {
  .content-box {
    padding: 2.5rem;
  }
}

.content-box::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 4px;
  height: 100%;
  background: var(--accent-teal);
  transition: width 0.3s ease;
}

.content-box:nth-child(even)::before {
  background: #6c5ce7;
}

.content-box:hover {
  transform: translateY(-5px);
  box-shadow: 0 12px 40px var(--shadow-medium);
}

.content-box:hover::before {
  width: 8px;
}

.content-box h2 {
  color: var(--text-dark);
  font-size: var(--font-size-xl);
  margin: 0 0 var(--spacing-md) 0;
  padding-bottom: var(--spacing-sm);
  border-bottom: 2px solid rgba(116, 185, 255, 0.3);
  font-family: 'Poppins', sans-serif;
  font-weight: 600;
  text-align: center;
  word-wrap: break-word;
  hyphens: auto;
}

.content-box p {
  color: #212121;
  line-height: 1.7;
  margin-bottom: var(--spacing-sm);
  word-wrap: break-word;
  hyphens: auto;
}

/* ===== Search Bar ===== */
.gcse-search {
  padding: var(--spacing-sm) var(--spacing-md);
  max-width: 100%;
  margin: var(--spacing-lg) auto;
  width: 100%;
}

@media (min-width: 769px) {
  .gcse-search {
    max-width: 600px;
  }
}

.gsc-control-cse {
  background-color: transparent !important;
  border: none !important;
  padding: 0 !important;
}

.gsc-input-box {
  border-radius: 20px !important;
  border: 1px solid #3498db !important;
  width: 100% !important;
}

.gsc-search-button {
  display: none !important;
}

.gsc-input {
  font-size: var(--font-size-sm) !important;
  padding-left: var(--spacing-sm) !important;
}

/* ===== Question Components ===== */
.question {
  margin-bottom: var(--spacing-lg);
  padding: var(--spacing-md);
  border: 1px solid var(--border-light);
  border-radius: 16px;
  background-color: var(--bg-white);
  transition: all 0.3s ease;
}

.options {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--spacing-sm);
  margin: var(--spacing-sm) 0;
}

@media (min-width: 769px) {
  .options {
    grid-template-columns: repeat(2, 1fr);
  }
}

.option {
  padding: var(--spacing-sm) var(--spacing-sm);
  background-color: #f8f9fa;
  color: #212121;
  border: 2px solid var(--border-light);
  border-radius: 8px;
  cursor: pointer;
  font-size: var(--font-size-sm);
  text-align: left;
  transition: all 0.3s ease;
  min-height: 44px; /* Touch-friendly */
  display: flex;
  align-items: center;
  word-wrap: break-word;
}

.option:hover {
  background-color: #e9ecef;
  transform: translateY(-2px);
  box-shadow: 0 3px 6px var(--shadow-medium);
}

.option:disabled {
  cursor: not-allowed;
  opacity: 0.7;
}

.option.correct {
  background-color: #d4edda;
  border-color: #c3e6cb;
}

.option.incorrect {
  background-color: #f8d7da;
  border-color: #f5c6cb;
}

/* ===== Whiteboard ===== */
.whiteboard {
  width: 100%;
  height: 300px;
  border: 2px solid #333;
  margin: var(--spacing-sm) auto;
  background-color: var(--bg-white);
  touch-action: none;
  border-radius: 8px;
  box-shadow: 0 2px 4px var(--shadow-medium);
}

@media (min-width: 769px) {
  .whiteboard {
    height: 500px;
  }
}

.whiteboard-controls {
  margin-top: var(--spacing-xs);
  display: flex;
  gap: var(--spacing-xs);
  flex-wrap: wrap;
}

.whiteboard-controls button {
  padding: var(--spacing-sm) var(--spacing-sm);
  background-color: #6c757d;
  color: var(--bg-white);
  border: none;
  border-radius: 5px;
  cursor: pointer;
  transition: background-color 0.2s;
  min-height: 44px; /* Touch-friendly */
  font-size: var(--font-size-sm);
}

.whiteboard-controls button:hover {
  background-color: #5a6268;
}

/* ===== Feedback ===== */
.feedback {
  margin-top: var(--spacing-xs);
  padding: var(--spacing-xs);
  border-radius: 4px;
  font-size: var(--font-size-sm);
}

/* ===== Resource Cards ===== */
.resource-link {
  display: block;
  background: var(--bg-card);
  border: 2px solid #dfe6e9;
  border-radius: 10px;
  margin-bottom: var(--spacing-lg);
  text-decoration: none;
  transition: transform 0.2s ease, border-color 0.2s ease;
  overflow: hidden;
}

.resource-link:hover {
  transform: scale(1.02);
  border-color: var(--accent-blue);
}

.resource-text {
  padding: var(--spacing-lg);
  color: var(--text-dark);
}

.resource-text h3 {
  margin: 0 0 var(--spacing-sm) 0;
  font-size: var(--font-size-lg);
  color: var(--accent-blue);
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  word-wrap: break-word;
}

.resource-text p {
  margin: 0;
  font-size: var(--font-size-base);
  color: #424242;
}

.resource-link:hover h3 {
  color: #2ecc71;
}

/* ===== Unit List ===== */
.units {
  list-style-type: none;
  padding: 0;
}

.units li {
  font-size: var(--font-size-lg);
  font-weight: bold;
  margin: var(--spacing-sm) 0;
}

.units li a {
  text-decoration: none;
  color: #4caf50;
  transition: color 0.3s, text-shadow 0.3s;
  word-wrap: break-word;
  display: block;
  padding: var(--spacing-xs);
  min-height: 44px; /* Touch-friendly */
  display: flex;
  align-items: center;
}

.units li a:hover {
  color: #388e3c;
  text-shadow: 1px 1px 5px #555;
}

/* ===== Activity Button ===== */
.activity-button {
  display: inline-block;
  padding: var(--spacing-sm) var(--spacing-lg);
  margin-top: var(--spacing-md);
  background: linear-gradient(135deg, #3498db, #2ecc71);
  color: white;
  text-decoration: none;
  border-radius: 25px;
  font-weight: bold;
  transition: all 0.3s ease;
  border: none;
  cursor: pointer;
  box-shadow: 0 3px 6px var(--shadow-medium);
  font-size: var(--font-size-base);
  min-height: 44px; /* Touch-friendly */
  display: inline-flex;
  align-items: center;
  justify-content: center;
  text-align: center;
}

.activity-button:hover {
  transform: translateY(-2px);
  box-shadow: 0 5px 15px var(--shadow-dark);
  background: linear-gradient(135deg, #2ecc71, #3498db);
}

.activity-button:active {
  transform: translateY(0);
  box-shadow: 0 2px 4px var(--shadow-medium);
}

/* ===== Footer ===== */
footer {
  background-color: var(--text-dark);
  color: white;
  padding: var(--spacing-lg) var(--spacing-sm);
  text-align: center;
  font-size: var(--font-size-sm);
  margin-top: var(--spacing-xl);
  border-top: 5px solid #388e3c;
}

footer p {
  margin: 0;
  opacity: 0.8;
  word-wrap: break-word;
  hyphens: auto;
}

/* ===== Help Section ===== */
.intro-section {
  text-align: center;
  margin-bottom: var(--spacing-sm);
}

.help-section {
  max-width: 100%;
  margin: var(--spacing-sm) auto var(--spacing-lg) auto;
  padding: var(--spacing-md);
  text-align: center;
  background-color: #f0f4ff;
  border-radius: 12px;
  border: 1px solid #d1ecf1;
}

@media (min-width: 769px) {
  .help-section {
    max-width: 600px;
    padding: var(--spacing-lg);
  }
}

/* ===== Performance Optimizations ===== */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* ===== Touch Improvements ===== */
@media (hover: none) {
  .option:hover,
  .resource-link:hover,
  .activity-button:hover {
    transform: none;
  }
}

/* ===== High DPI Display Support ===== */
@media (-webkit-min-device-pixel-ratio: 2), (min-resolution: 192dpi) {
  /* Optimize for high DPI displays */
  body {
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
  }
}

/* ===== Accessibility Improvements ===== */
@media (prefers-contrast: high) {
  .content-box {
    border: 2px solid var(--text-dark);
  }
  
  .nav-links a {
    border: 1px solid rgba(255, 255, 255, 0.3);
  }
}

/* ===== Focus States ===== */
button:focus,
a:focus,
input:focus,
select:focus,
textarea:focus {
  outline: 2px solid var(--primary-blue);
  outline-offset: 2px;
}

/* ===== Print Styles ===== */
@media print {
  .main-navbar,
  .mobile-menu-toggle,
  .gcse-search {
    display: none !important;
  }
  
  body {
    background: white !important;
    color: black !important;
  }
  
  .content-box {
    box-shadow: none !important;
    border: 1px solid #ccc !important;
  }
}

/* ===== Universal Grid and Layout Fixes ===== */
.stream-container {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--spacing-lg);
  margin-top: var(--spacing-lg);
  width: 100%;
}

@media (min-width: 769px) {
  .stream-container {
    grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
  }
}

.units-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--spacing-sm);
  margin-top: var(--spacing-sm);
  width: 100%;
}

@media (min-width: 480px) {
  .units-grid {
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  }
}

@media (min-width: 769px) {
  .units-grid {
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-lg);
  }
}

.unit-card {
  padding: var(--spacing-md);
  border-radius: 8px;
  background: #f8f9fa;
  transition: transform 0.3s ease;
  border: 1px solid #e0e0e0;
  text-decoration: none;
  color: var(--text-medium);
  display: block;
  width: 100%;
  box-sizing: border-box;
  min-height: 120px;
  display: flex;
  flex-direction: column;
  justify-content: flex-start;
}

.unit-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 4px 15px var(--shadow-medium);
  border-color: var(--primary-blue);
}

.unit-card h3 {
  color: var(--primary-blue);
  margin-bottom: var(--spacing-sm);
  font-size: var(--font-size-lg);
  word-wrap: break-word;
  hyphens: auto;
}

.unit-card p {
  line-height: 1.6;
  font-size: var(--font-size-sm);
  margin: 0;
  word-wrap: break-word;
  hyphens: auto;
}

.resources-box {
  background: #f8f9fa;
  border: 2px solid #2ecc71;
}

.resource-link {
  display: flex;
  align-items: center;
  padding: var(--spacing-sm);
  margin: var(--spacing-sm) 0;
  background: white;
  border-radius: 6px;
  transition: transform 0.3s ease;
  text-decoration: none;
  color: var(--text-medium);
  border: 1px solid #e0e0e0;
  min-height: 44px;
  word-wrap: break-word;
  box-sizing: border-box;
  width: 100%;
}

.resource-link:hover {
  transform: translateX(5px);
  border-color: var(--primary-blue);
  color: var(--primary-blue);
}

/* ===== Additional Mobile Optimizations ===== */
@media (max-width: 480px) {
  :root {
    --spacing-sm: 0.75rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
  }
  
  header {
    padding: var(--spacing-md) var(--spacing-xs);
  }
  
  main {
    margin: var(--spacing-xs);
    padding: var(--spacing-sm);
    border-radius: 8px;
  }
  
  .content-box {
    padding: var(--spacing-sm);
    border-radius: 12px;
  }
  
  footer {
    padding: var(--spacing-md) var(--spacing-xs);
  }
}