/* CSS Variables for Light/Dark Mode */
:root {
  /* Light Mode Colors */
  --bg-primary: #f9f9f9;
  --bg-secondary: #ffffff;
  --bg-tertiary: #f5f5f5;
  --text-primary: #333333;
  --text-secondary: #666666;
  --text-muted: #999999;
  --accent-primary: #007bff;
  --accent-secondary: #0056b3;
  --border-color: #e0e0e0;
  --shadow-light: rgba(0, 0, 0, 0.1);
  --shadow-medium: rgba(0, 0, 0, 0.15);
  --shadow-heavy: rgba(0, 0, 0, 0.25);
  
  /* Typography */
  --font-heading: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-body: 'Merriweather', Georgia, serif;
  --font-size-xs: 0.75rem;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.25rem;
  --font-size-2xl: 1.5rem;
  --font-size-3xl: 1.875rem;
  --font-size-4xl: 2.25rem;
  --font-size-5xl: 3rem;
  
  /* Spacing */
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-2xl: 3rem;
  --spacing-3xl: 4rem;
  
  /* Layout */
  --container-max-width: 1200px;
  --content-max-width: 800px;
  --border-radius: 8px;
  --border-radius-lg: 12px;
  
  /* Transitions */
  --transition-fast: 0.15s ease;
  --transition-normal: 0.3s ease;
  --transition-slow: 0.5s ease;
}

/* Dark Mode Colors */
[data-theme="dark"] {
  --bg-primary: #1a1a1a;
  --bg-secondary: #2d2d2d;
  --bg-tertiary: #404040;
  --text-primary: #cccccc;
  --text-secondary: #999999;
  --text-muted: #666666;
  --accent-primary: #4da6ff;
  --accent-secondary: #0080ff;
  --border-color: #404040;
  --shadow-light: rgba(0, 0, 0, 0.3);
  --shadow-medium: rgba(0, 0, 0, 0.4);
  --shadow-heavy: rgba(0, 0, 0, 0.6);
}

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

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

body {
  font-family: var(--font-body);
  font-size: var(--font-size-base);
  line-height: 1.7;
  color: var(--text-primary);
  background-color: var(--bg-primary);
  transition: background-color var(--transition-normal), color var(--transition-normal);
  overflow-x: hidden;
}

/* Loading Screen */
.loading-screen {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: var(--bg-primary);
  display: flex;
  justify-content: center;
  align-items: center;
  z-index: 9999;
  transition: opacity var(--transition-slow), visibility var(--transition-slow);
}

.loading-screen.hidden {
  opacity: 0;
  visibility: hidden;
}

.loader {
  display: flex;
  gap: var(--spacing-sm);
}

.loader-dot {
  width: 12px;
  height: 12px;
  background-color: var(--accent-primary);
  border-radius: 50%;
  animation: loader-bounce 1.4s ease-in-out infinite both;
}

.loader-dot:nth-child(1) { animation-delay: -0.32s; }
.loader-dot:nth-child(2) { animation-delay: -0.16s; }

@keyframes loader-bounce {
  0%, 80%, 100% {
    transform: scale(0);
  }
  40% {
    transform: scale(1);
  }
}

/* Scroll Progress Bar */
.scroll-progress {
  position: fixed;
  top: 0;
  left: 0;
  width: 0%;
  height: 3px;
  background: linear-gradient(90deg, var(--accent-primary), var(--accent-secondary));
  z-index: 1000;
  transition: width var(--transition-fast);
}

/* Navigation */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  background-color: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border-color);
  z-index: 999;
  transition: all var(--transition-normal);
}

[data-theme="dark"] .navbar {
  background-color: rgba(26, 26, 26, 0.95);
}

.nav-container {
  max-width: var(--container-max-width);
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 70px;
}

.nav-brand .brand-link {
  font-family: var(--font-heading);
  font-size: var(--font-size-xl);
  font-weight: 700;
  color: var(--text-primary);
  text-decoration: none;
  transition: color var(--transition-fast);
}

.nav-brand .brand-link:hover {
  color: var(--accent-primary);
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: var(--spacing-xl);
}

.nav-link {
  font-family: var(--font-heading);
  font-size: var(--font-size-sm);
  font-weight: 500;
  color: var(--text-secondary);
  text-decoration: none;
  padding: var(--spacing-sm) var(--spacing-md);
  border-radius: var(--border-radius);
  transition: all var(--transition-fast);
  position: relative;
}

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

.nav-link::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 50%;
  width: 0;
  height: 2px;
  background-color: var(--accent-primary);
  transition: all var(--transition-fast);
  transform: translateX(-50%);
}

.nav-link:hover::after {
  width: 80%;
}

/* Theme Toggle */
.theme-toggle {
  background: none;
  border: 2px solid var(--border-color);
  border-radius: 50%;
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all var(--transition-fast);
  font-size: var(--font-size-lg);
}

.theme-toggle:hover {
  border-color: var(--accent-primary);
  transform: scale(1.1);
}

/* Mobile Navigation */
.nav-hamburger {
  display: none;
  flex-direction: column;
  cursor: pointer;
  gap: 4px;
}

.nav-hamburger span {
  width: 25px;
  height: 3px;
  background-color: var(--text-primary);
  transition: all var(--transition-fast);
}

.nav-hamburger.active span:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}

.nav-hamburger.active span:nth-child(2) {
  opacity: 0;
}

.nav-hamburger.active span:nth-child(3) {
  transform: rotate(-45deg) translate(7px, -6px);
}

/* Container */
.container {
  max-width: var(--container-max-width);
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
}

/* Main Content */
.main-content {
  margin-top: 70px;
}

/* Hero Section */
.hero-section {
  padding: var(--spacing-3xl) 0;
  background: linear-gradient(135deg, var(--bg-primary) 0%, var(--bg-secondary) 100%);
  text-align: center;
  position: relative;
  overflow: hidden;
}

.hero-section::before {
  content: '';
  position: absolute;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: radial-gradient(circle, rgba(0, 123, 255, 0.1) 0%, transparent 70%);
  animation: hero-float 20s ease-in-out infinite;
}

@keyframes hero-float {
  0%, 100% { transform: translate(0, 0) rotate(0deg); }
  33% { transform: translate(30px, -30px) rotate(120deg); }
  66% { transform: translate(-20px, 20px) rotate(240deg); }
}

.blog-hero-content {
  position: relative;
  z-index: 1;
  animation: fade-in-up 1s ease-out;
  width: 100%;
}

.hero-title {
  font-family: var(--font-heading);
  font-size: var(--font-size-5xl);
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: var(--spacing-lg);
  line-height: 1.2;
}

.blog-hero-content p {
  font-size: var(--font-size-xl);
  color: var(--text-muted);
  margin-bottom: var(--spacing-2xl);
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

.cta-button {
  display: inline-block;
  font-family: var(--font-heading);
  font-size: var(--font-size-lg);
  font-weight: 600;
  color: white;
  background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
  padding: var(--spacing-lg) var(--spacing-2xl);
  border-radius: var(--border-radius-lg);
  text-decoration: none;
  transition: all var(--transition-normal);
  box-shadow: 0 4px 15px var(--shadow-light);
  position: relative;
  overflow: hidden;
}

.cta-button::before {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
  transition: left var(--transition-slow);
}

.cta-button:hover::before {
  left: 100%;
}

.cta-button:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 25px var(--shadow-medium);
}

/* Featured Article */
.featured-article {
  padding: var(--spacing-3xl) 0;
  background-color: var(--bg-secondary);
}

.article-card {
  background-color: var(--bg-secondary);
  border-radius: var(--border-radius-lg);
  padding: var(--spacing-2xl);
  box-shadow: 0 4px 20px var(--shadow-light);
  transition: all var(--transition-normal);
  animation: fade-in-up 0.8s ease-out;
}

.article-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 8px 30px var(--shadow-medium);
}

.article-card.featured {
  max-width: var(--content-max-width);
  margin: 0 auto;
  border: 2px solid var(--accent-primary);
}

.article-meta {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  margin-bottom: var(--spacing-lg);
  font-family: var(--font-heading);
  font-size: var(--font-size-sm);
}

.article-category {
  background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
  color: white;
  padding: var(--spacing-xs) var(--spacing-md);
  border-radius: var(--border-radius);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.article-date {
  color: var(--text-muted);
}

.article-title {
  font-family: var(--font-heading);
  font-size: var(--font-size-3xl);
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: var(--spacing-lg);
  line-height: 1.3;
}

.article-excerpt {
  font-size: var(--font-size-lg);
  color: var(--text-secondary);
  margin-bottom: var(--spacing-xl);
  line-height: 1.6;
}

.article-content {
  font-size: var(--font-size-lg);
  line-height: 1.8;
  color: var(--text-primary);
}

.article-content h3 {
  font-family: var(--font-heading);
  font-size: var(--font-size-2xl);
  font-weight: 600;
  color: var(--text-primary);
  margin: var(--spacing-2xl) 0 var(--spacing-lg) 0;
  line-height: 1.4;
}

.article-content p {
  margin-bottom: var(--spacing-lg);
}

/* Drop Cap */
.drop-cap-paragraph {
  position: relative;
}

.drop-cap {
  float: left;
  font-family: var(--font-heading);
  font-size: 4rem;
  font-weight: 700;
  line-height: 1;
  color: var(--accent-primary);
  margin: 0 var(--spacing-sm) 0 0;
  padding: var(--spacing-xs);
}

/* Collapsible Sections */
.collapsible-section {
  margin: var(--spacing-xl) 0;
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius);
  overflow: hidden;
}

.collapsible-toggle {
  width: 100%;
  background-color: var(--bg-tertiary);
  border: none;
  padding: var(--spacing-lg);
  font-family: var(--font-heading);
  font-size: var(--font-size-lg);
  font-weight: 600;
  color: var(--text-primary);
  text-align: left;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  transition: all var(--transition-fast);
}

.collapsible-toggle:hover {
  background-color: var(--bg-primary);
}

.collapsible-toggle[aria-expanded="true"] .toggle-icon {
  transform: rotate(45deg);
}

.toggle-icon {
  font-size: var(--font-size-xl);
  transition: transform var(--transition-fast);
}

.collapsible-content {
  max-height: 0;
  overflow: hidden;
  transition: max-height var(--transition-normal);
}

.collapsible-content.expanded {
  max-height: 1000px;
  padding: var(--spacing-lg);
}

 /* Grammar FAQ - themed to your CSS variables */
.grammar-faq {
  max-width: 800px;
  margin: var(--spacing-md) 0;
  padding: calc(var(--spacing-md) * 1);
  border-radius: var(--border-radius);
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  box-shadow: 0 6px 18px var(--shadow-light);
  color: var(--text-primary);
  font-family: var(--font-body);
  font-size: var(--font-size-base);
  line-height: 1.5;
}

/* Question row */
.grammar-faq dt {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--spacing-sm);
  font-weight: 600;
  margin: 0.5rem 0 0.25rem 0;
  cursor: pointer;
  position: relative;
  padding: calc(var(--spacing-sm) * 0.6) calc(var(--spacing-md) * 0.2);
  color: var(--text-primary);
  background: transparent;
  border-radius: 6px;
  transition: background var(--transition-fast), color var(--transition-fast), transform var(--transition-fast);
}

/* Hover / focus affordance */
.grammar-faq dt:hover,
.grammar-faq dt:focus {
  background: var(--bg-tertiary);
  color: var(--text-primary);
  transform: translateY(-1px);
  outline: none;
}

/* Caret */
.grammar-faq dt::after {
  content: "▸";
  margin-left: var(--spacing-sm);
  transform-origin: center;
  transition: transform var(--transition-fast), color var(--transition-fast);
  font-size: 0.95rem;
  color: var(--accent-primary);
}

/* Answer block: animated collapse (max-height + opacity) */
.grammar-faq dd {
  margin: 0 0 var(--spacing-sm) 0;
  padding: 0.6rem calc(var(--spacing-md) * 0.5);
  color: var(--text-secondary);
  background: transparent;
  border-left: 3px solid rgba(0,0,0,0); /* visually becomes accent when open */
  overflow: hidden;
  max-height: 1000px; /* large enough for full content when open */
  opacity: 1;
  transition: max-height var(--transition-normal) ease, opacity var(--transition-fast) ease, border-color var(--transition-fast) ease;
  font-size: var(--font-size-sm);
  border-radius: 4px;
}

/* Closed state (hidden) */
.grammar-faq dd.hidden {
  max-height: 0;
  opacity: 0;
  padding-top: 0;
  padding-bottom: 0;
  margin-bottom: 0;
  border-left-color: rgba(0,0,0,0);
}

/* When question is open, rotate caret and show accent border */
.grammar-faq dt.open::after {
  transform: rotate(90deg);
  color: var(--accent-secondary);
}
.grammar-faq dt.open + dd {
  border-left-color: var(--accent-primary);
}

/* Small improvements for inline code inside FAQ */
.grammar-faq code {
  background: var(--bg-tertiary);
  padding: 0.12rem 0.35rem;
  border-radius: 4px;
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, "Roboto Mono", "Courier New", monospace;
  font-size: 0.92em;
  color: var(--text-primary);
}

/* Accessibility: visible focus outline */
.grammar-faq dt:focus {
  box-shadow: 0 0 0 4px rgba(0, 123, 255, 0.12);
  outline: none;
}



/* Highlight Quote */
.highlight-quote {
  background: linear-gradient(135deg, var(--bg-tertiary), var(--bg-secondary));
  border-left: 4px solid var(--accent-primary);
  padding: var(--spacing-xl);
  margin: var(--spacing-xl) 0;
  border-radius: 0 var(--border-radius) var(--border-radius) 0;
  font-style: italic;
  font-size: var(--font-size-lg);
  position: relative;
}

.highlight-quote::before {
  content: '"';
  font-size: 4rem;
  color: var(--accent-primary);
  position: absolute;
  top: -10px;
  left: var(--spacing-lg);
  opacity: 0.3;
}

.highlight-quote cite {
  display: block;
  margin-top: var(--spacing-md);
  font-size: var(--font-size-base);
  color: var(--text-secondary);
  font-style: normal;
}

/* Side Highlight */
.side-highlight {
  background-color: var(--bg-tertiary);
  border-radius: var(--border-radius);
  padding: var(--spacing-lg);
  margin: var(--spacing-xl) 0;
  border-left: 4px solid var(--accent-primary);
}

.side-highlight h4 {
  font-family: var(--font-heading);
  font-size: var(--font-size-lg);
  font-weight: 600;
  color: var(--accent-primary);
  margin-bottom: var(--spacing-sm);
}

/* Article Footer */
.article-footer {
  margin-top: var(--spacing-2xl);
  padding-top: var(--spacing-xl);
  border-top: 1px solid var(--border-color);
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--spacing-lg);
}

.article-tags {
  display: flex;
  gap: var(--spacing-sm);
  flex-wrap: wrap;
}

.tag {
  background-color: var(--bg-tertiary);
  color: var(--text-secondary);
  padding: var(--spacing-xs) var(--spacing-sm);
  border-radius: var(--border-radius);
  font-family: var(--font-heading);
  font-size: var(--font-size-xs);
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  transition: all var(--transition-fast);
}

.tag:hover {
  background-color: var(--accent-primary);
  color: white;
}

.article-share {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  font-family: var(--font-heading);
  font-size: var(--font-size-sm);
}

.share-text {
  color: var(--text-secondary);
  font-weight: 500;
}

.share-link {
  color: var(--text-secondary);
  text-decoration: none;
  padding: var(--spacing-xs) var(--spacing-sm);
  border-radius: var(--border-radius);
  transition: all var(--transition-fast);
}

.share-link:hover {
  color: var(--accent-primary);
  background-color: var(--bg-tertiary);
}

/* Articles Section */
.articles-section {
  padding: var(--spacing-3xl) 0;
  background-color: var(--bg-primary);
}

.section-title {
  font-family: var(--font-heading);
  font-size: var(--font-size-4xl);
  font-weight: 700;
  color: var(--text-primary);
  text-align: center;
  margin-bottom: var(--spacing-2xl);
  position: relative;
}

.section-title::after {
  content: '';
  position: absolute;
  bottom: -10px;
  left: 50%;
  width: 60px;
  height: 3px;
  background: linear-gradient(90deg, var(--accent-primary), var(--accent-secondary));
  transform: translateX(-50%);
  border-radius: var(--border-radius);
}

.articles-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--spacing-xl);
  margin-top: var(--spacing-2xl);
}

.articles-grid .article-card {
  background-color: var(--bg-secondary);
}

.articles-grid .article-title {
  font-size: var(--font-size-xl);
  margin-bottom: var(--spacing-md);
}

.read-more {
  display: inline-block;
  font-family: var(--font-heading);
  font-size: var(--font-size-sm);
  font-weight: 600;
  color: var(--accent-primary);
  text-decoration: none;
  margin-top: var(--spacing-md);
  padding: var(--spacing-sm) 0;
  border-bottom: 2px solid transparent;
  transition: all var(--transition-fast);
}

.read-more:hover {
  border-bottom-color: var(--accent-primary);
}

/* About Section */
.about-section {
  padding: var(--spacing-3xl) 0;
  background-color: var(--bg-secondary);
}

.about-content {
  max-width: var(--content-max-width);
  margin: 0 auto;
  text-align: center;
}

.about-text {
  font-size: var(--font-size-lg);
  color: var(--text-secondary);
  margin-bottom: var(--spacing-lg);
  line-height: 1.7;
}

/* Author Bio */
.author-bio {
  padding: var(--spacing-2xl) 0;
  background-color: var(--bg-tertiary);
}

.bio-card {
  max-width: var(--content-max-width);
  margin: 0 auto;
  background-color: var(--bg-secondary);
  border-radius: var(--border-radius-lg);
  padding: var(--spacing-2xl);
  box-shadow: 0 4px 20px var(--shadow-light);
  display: flex;
  gap: var(--spacing-xl);
  align-items: center;
  animation: fade-in-up 0.8s ease-out;
}

.bio-avatar {
  flex-shrink: 0;
}

.avatar-placeholder {
  width: 80px;
  height: 80px;
  background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-heading);
  font-size: var(--font-size-xl);
  font-weight: 700;
  color: white;
}

.bio-content {
  flex: 1;
}

.bio-name {
  font-family: var(--font-heading);
  font-size: var(--font-size-2xl);
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: var(--spacing-xs);
}

.bio-title {
  font-family: var(--font-heading);
  font-size: var(--font-size-base);
  font-weight: 500;
  color: var(--accent-primary);
  margin-bottom: var(--spacing-md);
}

.bio-description {
  color: var(--text-secondary);
  margin-bottom: var(--spacing-lg);
  line-height: 1.6;
}

.bio-links {
  display: flex;
  gap: var(--spacing-md);
}

.bio-link {
  font-family: var(--font-heading);
  font-size: var(--font-size-sm);
  font-weight: 500;
  color: var(--text-secondary);
  text-decoration: none;
  padding: var(--spacing-xs) var(--spacing-sm);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius);
  transition: all var(--transition-fast);
}

.bio-link:hover {
  color: var(--accent-primary);
  border-color: var(--accent-primary);
  background-color: var(--bg-tertiary);
}

/* Footer */
.footer {
  background-color: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  padding: var(--spacing-2xl) 0 var(--spacing-lg) 0;
}

.footer-content {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: var(--spacing-xl);
  margin-bottom: var(--spacing-xl);
}

.footer-title {
  font-family: var(--font-heading);
  font-size: var(--font-size-lg);
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--spacing-md);
}

.footer-text {
  color: var(--text-secondary);
  line-height: 1.6;
}

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

.footer-links li {
  margin-bottom: var(--spacing-sm);
}

.footer-links a {
  color: var(--text-secondary);
  text-decoration: none;
  transition: color var(--transition-fast);
}

.footer-links a:hover {
  color: var(--accent-primary);
}

.footer-bottom {
  text-align: center;
  padding-top: var(--spacing-lg);
  border-top: 1px solid var(--border-color);
  color: var(--text-muted);
  font-size: var(--font-size-sm);
}

/* Back to Top Button */
.back-to-top {
  position: fixed;
  bottom: var(--spacing-xl);
  right: var(--spacing-xl);
  width: 50px;
  height: 50px;
  background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
  color: white;
  border: none;
  border-radius: 50%;
  cursor: pointer;
  font-size: var(--font-size-xl);
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 4px 15px var(--shadow-medium);
  transition: all var(--transition-normal);
  opacity: 0;
  visibility: hidden;
  transform: translateY(20px);
  z-index: 998;
}

.back-to-top.visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.back-to-top:hover {
  transform: translateY(-3px);
  box-shadow: 0 6px 20px var(--shadow-heavy);
}

/* Animations */
@keyframes fade-in-up {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.fade-in-up {
  animation: fade-in-up 0.8s ease-out;
}

/* Responsive Design */
@media (max-width: 768px) {
  :root {
    --font-size-5xl: 2.5rem;
    --font-size-4xl: 2rem;
    --font-size-3xl: 1.5rem;
    --spacing-3xl: 2rem;
  }

  .nav-menu {
    position: fixed;
    top: 70px;
    left: -100%;
    width: 100%;
    height: calc(100vh - 70px);
    background-color: var(--bg-secondary);
    flex-direction: column;
    justify-content: flex-start;
    align-items: center;
    padding-top: var(--spacing-2xl);
    transition: left var(--transition-normal);
    border-top: 1px solid var(--border-color);
  }

  .nav-menu.active {
    left: 0;
  }

  .nav-hamburger {
    display: flex;
  }

  .hero-title {
    font-size: var(--font-size-4xl);
  }

  .hero-subtitle {
    font-size: var(--font-size-lg);
  }

  .article-title {
    font-size: var(--font-size-2xl);
  }

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

  .article-footer {
    flex-direction: column;
    align-items: flex-start;
  }
  

  .grammar-faq {
    padding: calc(var(--spacing-sm) * 1.2);
    font-size: var(--font-size-sm);
  }
  .grammar-faq dd {
    font-size: 0.95rem;
  }

  .bio-card {
    flex-direction: column;
    text-align: center;
  }

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

  .footer-content {
    grid-template-columns: 1fr;
    text-align: center;
  }

  .container {
    padding: 0 var(--spacing-md);
  }
}

@media (max-width: 480px) {
  .hero-title {
    font-size: var(--font-size-3xl);
  }

  .cta-button {
    padding: var(--spacing-md) var(--spacing-lg);
    font-size: var(--font-size-base);
  }

  .article-card {
    padding: var(--spacing-lg);
  }

  .bio-card {
    padding: var(--spacing-lg);
  }

  .back-to-top {
    bottom: var(--spacing-lg);
    right: var(--spacing-lg);
    width: 45px;
    height: 45px;
  }
}

/* Accessibility */
@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
  
  html {
    scroll-behavior: auto;
  }
}

/* Focus Styles */
*:focus {
  outline: 2px solid var(--accent-primary);
  outline-offset: 2px;
}

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

/* High Contrast Mode */
@media (prefers-contrast: high) {
  :root {
    --shadow-light: rgba(0, 0, 0, 0.3);
    --shadow-medium: rgba(0, 0, 0, 0.5);
    --shadow-heavy: rgba(0, 0, 0, 0.7);
  }
}

/* Print Styles */
@media print {
  .navbar,
  .back-to-top,
  .scroll-progress,
  .loading-screen {
    display: none !important;
  }
  
  .main-content {
    margin-top: 0;
  }
  
  body {
    background: white;
    color: black;
  }
  
  .article-card {
    box-shadow: none;
    border: 1px solid #ccc;
  }
}
/* Respect reduced motion */
@media (prefers-reduced-motion: reduce) {
  .grammar-faq dt,
  .grammar-faq dt::after,
  .grammar-faq dd {
    transition: none !important;
  }
}