/* ==========================================================================
   Base Styles & Typography System
   ========================================================================== */

/* CSS Reset and Base Variables */
:root {
  /* Colors inspired by Medium's clean palette */
  --color-primary: #2962ff;
  --color-primary-dark: #0039cb;
  --color-text-primary: #191919;
  --color-text-secondary: #757575;
  --color-text-tertiary: #9e9e9e;
  --color-background: #ffffff;
  --color-surface: #f5f5f5;
  --color-border: #e0e0e0;
  --color-accent: #ff6b6b;
  
  /* Typography scale - fluid typography for responsive design */
  --font-family-primary: 'Georgia', 'Times New Roman', serif;
  --font-family-secondary: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue', sans-serif;
  --font-family-mono: 'SF Mono', 'Monaco', 'Inconsolata', 'Roboto Mono', 'Source Code Pro', monospace;
  
  /* Fluid typography values */
  --font-size-xs: clamp(0.75rem, 0.7rem + 0.25vw, 0.875rem);
  --font-size-sm: clamp(0.875rem, 0.8rem + 0.375vw, 1rem);
  --font-size-base: clamp(1rem, 0.9rem + 0.5vw, 1.125rem);
  --font-size-lg: clamp(1.125rem, 1rem + 0.625vw, 1.25rem);
  --font-size-xl: clamp(1.25rem, 1.1rem + 0.75vw, 1.5rem);
  --font-size-2xl: clamp(1.5rem, 1.3rem + 1vw, 2rem);
  --font-size-3xl: clamp(2rem, 1.7rem + 1.5vw, 2.5rem);
  --font-size-4xl: clamp(2.5rem, 2rem + 2.5vw, 3.5rem);
  
  /* Line heights optimized for readability */
  --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;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.25rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;
  --space-24: 6rem;
  
  /* Container widths for optimal reading (45-75 characters) */
  --container-sm: 40rem;  /* ~640px - good for mobile */
  --container-md: 48rem;  /* ~768px - tablet */
  --container-lg: 64rem;  /* ~1024px - desktop */
  --container-xl: 80rem;  /* ~1280px - large desktop */
  
  /* Breakpoints */
  --breakpoint-sm: 40rem;
  --breakpoint-md: 48rem;
  --breakpoint-lg: 64rem;
  --breakpoint-xl: 80rem;
  
  /* Border radius */
  --radius-sm: 0.125rem;
  --radius-md: 0.375rem;
  --radius-lg: 0.5rem;
  --radius-xl: 1rem;
  
  /* 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);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
  
  /* Transitions */
  --transition-fast: 150ms ease-in-out;
  --transition-normal: 250ms ease-in-out;
  --transition-slow: 350ms ease-in-out;
}

/* Reset and base styles */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

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

body {
  font-family: var(--font-family-secondary);
  font-size: var(--font-size-base);
  line-height: var(--line-height-relaxed);
  color: var(--color-text-primary);
  background-color: var(--color-background);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
}

/* Skip link for accessibility */
.skip-link {
  position: absolute;
  top: -40px;
  left: 6px;
  background: var(--color-primary);
  color: white;
  padding: var(--space-2) var(--space-4);
  text-decoration: none;
  border-radius: var(--radius-md);
  z-index: 1000;
  transition: top var(--transition-fast);
}

.skip-link:focus {
  top: 6px;
}

/* Typography utilities */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-family-primary);
  font-weight: 700;
  line-height: var(--line-height-tight);
  margin-bottom: var(--space-4);
  color: var(--color-text-primary);
}

h1 {
  font-size: var(--font-size-4xl);
  letter-spacing: -0.02em;
  margin-bottom: var(--space-6);
}

h2 {
  font-size: var(--font-size-3xl);
  letter-spacing: -0.01em;
  margin-bottom: var(--space-5);
  margin-top: var(--space-12);
}

h3 {
  font-size: var(--font-size-2xl);
  letter-spacing: -0.005em;
  margin-bottom: var(--space-4);
  margin-top: var(--space-8);
}

p {
  margin-bottom: var(--space-4);
  max-width: 65ch; /* Optimal reading line length */
}

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

a:hover,
a:focus {
  color: var(--color-primary-dark);
  text-decoration: underline;
  outline: none;
}

a:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}

/* ==========================================================================
   Layout Components
   ========================================================================== */

/* Container with optimal reading width */
.container {
  width: 100%;
  max-width: var(--container-lg);
  margin: 0 auto;
  padding: 0 var(--space-4);
}

.container-sm {
  max-width: var(--container-sm);
}

.container-md {
  max-width: var(--container-md);
}

.container-xl {
  max-width: var(--container-xl);
}

/* ==========================================================================
   Header & Navigation
   ========================================================================== */

.header {
  background-color: var(--color-background);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(10px);
  background-color: rgba(255, 255, 255, 0.95);
}

.nav-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 4rem;
  max-width: var(--container-xl);
  margin: 0 auto;
  padding: 0 var(--space-4);
}

.nav-logo {
  font-family: var(--font-family-primary);
  font-size: var(--font-size-xl);
  font-weight: 700;
  color: var(--color-text-primary);
  text-decoration: none;
}

.nav-menu {
  display: flex;
  list-style: none;
  gap: var(--space-6);
}

.nav-menu a {
  font-size: var(--font-size-sm);
  font-weight: 500;
  color: var(--color-text-secondary);
  text-decoration: none;
  transition: color var(--transition-fast);
}

.nav-menu a:hover,
.nav-menu a:focus {
  color: var(--color-primary);
}

.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--space-2);
}

.hamburger {
  display: block;
  width: 24px;
  height: 2px;
  background-color: var(--color-text-primary);
  position: relative;
  transition: background-color var(--transition-fast);
}

.hamburger::before,
.hamburger::after {
  content: '';
  position: absolute;
  width: 24px;
  height: 2px;
  background-color: var(--color-text-primary);
  transition: transform var(--transition-fast);
}

.hamburger::before {
  top: -8px;
}

.hamburger::after {
  top: 8px;
}

/* ==========================================================================
   Main Content & Article Layout
   ========================================================================== */

.main {
  flex: 1;
  padding: var(--space-8) 0;
}

.article {
  max-width: 65ch; /* Optimal reading width */
  margin: 0 auto;
  padding: 0 var(--space-4);
}

.article-header {
  text-align: center;
  margin-bottom: var(--space-12);
}

.article-title {
  font-size: var(--font-size-4xl);
  line-height: var(--line-height-tight);
  margin-bottom: var(--space-6);
  letter-spacing: -0.02em;
}

.article-meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  flex-wrap: wrap;
}

.author-info {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

.author-avatar {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  object-fit: cover;
}

.author-details {
  text-align: left;
}

.author-name {
  font-family: var(--font-family-secondary);
  font-size: var(--font-size-base);
  font-weight: 600;
  color: var(--color-text-primary);
  font-style: normal;
}

.publish-date,
.reading-time {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
}

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

.article-section {
  margin-bottom: var(--space-8);
}

.article-section h2 {
  margin-top: var(--space-12);
  margin-bottom: var(--space-4);
}

.article-section h3 {
  margin-top: var(--space-8);
  margin-bottom: var(--space-3);
}

.article-hero {
  margin: var(--space-8) 0;
  border-radius: var(--radius-lg);
  overflow: hidden;
}

.hero-image {
  width: 100%;
  height: auto;
  display: block;
  object-fit: cover;
}

.image-caption {
  text-align: center;
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  margin-top: var(--space-3);
  font-style: italic;
}

.article-quote {
  margin: var(--space-8) 0;
  padding: var(--space-6) var(--space-8);
  background-color: var(--color-surface);
  border-left: 4px solid var(--color-primary);
  border-radius: var(--radius-md);
  font-style: italic;
}

.article-quote p {
  font-size: var(--font-size-xl);
  line-height: var(--line-height-relaxed);
  margin-bottom: var(--space-3);
  color: var(--color-text-primary);
}

.article-quote cite {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  font-style: normal;
  font-weight: 600;
}

.article-footer {
  margin-top: var(--space-12);
  padding-top: var(--space-8);
  border-top: 1px solid var(--color-border);
}

.article-tags {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  flex-wrap: wrap;
}

.tag-label {
  font-size: var(--font-size-sm);
  font-weight: 600;
  color: var(--color-text-secondary);
}

.tag {
  font-size: var(--font-size-xs);
  padding: var(--space-1) var(--space-3);
  background-color: var(--color-surface);
  color: var(--color-text-secondary);
  border-radius: var(--radius-xl);
  text-decoration: none;
  transition: all var(--transition-fast);
}

.tag:hover,
.tag:focus {
  background-color: var(--color-primary);
  color: white;
  text-decoration: none;
}

/* ==========================================================================
   Author Bio Section
   ========================================================================== */

.author-bio {
  background-color: var(--color-surface);
  padding: var(--space-12) 0;
  margin-top: var(--space-16);
}

.bio-container {
  max-width: var(--container-lg);
  margin: 0 auto;
  padding: 0 var(--space-4);
  display: flex;
  gap: var(--space-6);
  align-items: flex-start;
}

.bio-avatar {
  width: 120px;
  height: 120px;
  border-radius: 50%;
  object-fit: cover;
  flex-shrink: 0;
}

.bio-content h3 {
  margin-top: 0;
  margin-bottom: var(--space-3);
  font-size: var(--font-size-xl);
}

.bio-content p {
  margin-bottom: var(--space-4);
  color: var(--color-text-secondary);
}

.bio-social {
  display: flex;
  gap: var(--space-4);
}

.social-link {
  font-size: var(--font-size-sm);
  color: var(--color-primary);
  text-decoration: none;
  font-weight: 500;
  transition: color var(--transition-fast);
}

.social-link:hover,
.social-link:focus {
  color: var(--color-primary-dark);
}

/* ==========================================================================
   Related Articles
   ========================================================================== */

.related-articles {
  padding: var(--space-16) 0;
}

.related-container {
  max-width: var(--container-xl);
  margin: 0 auto;
  padding: 0 var(--space-4);
}

.related-container h2 {
  text-align: center;
  margin-bottom: var(--space-8);
}

.related-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--space-6);
}

.related-card {
  background: white;
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-normal);
  border: 1px solid var(--color-border);
}

.related-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.related-image {
  width: 100%;
  height: 200px;
  object-fit: cover;
}

.related-content {
  padding: var(--space-4);
}

.related-content h3 {
  margin: 0 0 var(--space-2) 0;
  font-size: var(--font-size-lg);
}

.related-content h3 a {
  color: var(--color-text-primary);
  text-decoration: none;
}

.related-content h3 a:hover,
.related-content h3 a:focus {
  color: var(--color-primary);
}

.related-content p {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  margin-bottom: var(--space-3);
  line-height: var(--line-height-normal);
}

.related-content time {
  font-size: var(--font-size-xs);
  color: var(--color-text-tertiary);
}

/* ==========================================================================
   Footer
   ========================================================================== */

.footer {
  background-color: var(--color-surface);
  border-top: 1px solid var(--color-border);
  padding: var(--space-12) 0 var(--space-6);
  margin-top: var(--space-16);
}

.footer-container {
  max-width: var(--container-xl);
  margin: 0 auto;
  padding: 0 var(--space-4);
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: var(--space-8);
  margin-bottom: var(--space-8);
}

.footer-section h3 {
  font-size: var(--font-size-lg);
  margin-bottom: var(--space-3);
  font-family: var(--font-family-secondary);
}

.footer-section p {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  margin-bottom: 0;
}

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

.footer-section ul li {
  margin-bottom: var(--space-2);
}

.footer-section ul li a {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  text-decoration: none;
  transition: color var(--transition-fast);
}

.footer-section ul li a:hover,
.footer-section ul li a:focus {
  color: var(--color-primary);
}

.social-links {
  display: flex;
  gap: var(--space-4);
}

.social-links a {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  text-decoration: none;
  font-weight: 500;
  transition: color var(--transition-fast);
}

.social-links a:hover,
.social-links a:focus {
  color: var(--color-primary);
}

.subscribe-form {
  display: flex;
  gap: var(--space-2);
  margin-top: var(--space-3);
}

.subscribe-form input {
  flex: 1;
  padding: var(--space-2) var(--space-3);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  font-size: var(--font-size-sm);
}

.subscribe-form button {
  padding: var(--space-2) var(--space-4);
  background-color: var(--color-primary);
  color: white;
  border: none;
  border-radius: var(--radius-md);
  font-size: var(--font-size-sm);
  font-weight: 500;
  cursor: pointer;
  transition: background-color var(--transition-fast);
}

.subscribe-form button:hover,
.subscribe-form button:focus {
  background-color: var(--color-primary-dark);
}

.footer-bottom {
  max-width: var(--container-xl);
  margin: 0 auto;
  padding: var(--space-6) var(--space-4) 0;
  border-top: 1px solid var(--color-border);
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--space-4);
}

.footer-bottom p {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  margin: 0;
}

.footer-links {
  display: flex;
  gap: var(--space-6);
}

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

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

/* ==========================================================================
   Social Sharing Component
   ========================================================================== */

.social-sharing {
  position: fixed;
  right: var(--space-4);
  top: 50%;
  transform: translateY(-50%);
  z-index: 50;
}

.share-toggle {
  display: block;
  padding: var(--space-3);
  background-color: var(--color-primary);
  color: white;
  border: none;
  border-radius: var(--radius-lg);
  font-size: var(--font-size-sm);
  font-weight: 500;
  cursor: pointer;
  box-shadow: var(--shadow-md);
  transition: all var(--transition-normal);
  writing-mode: vertical-rl;
  text-orientation: mixed;
}

.share-toggle:hover,
.share-toggle:focus {
  background-color: var(--color-primary-dark);
  transform: translateY(-50%) scale(1.05);
}

.share-menu {
  position: absolute;
  right: 100%;
  top: 50%;
  transform: translateY(-50%);
  background-color: white;
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-lg);
  border: 1px solid var(--color-border);
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition-normal);
  margin-right: var(--space-2);
  min-width: 120px;
}

.share-menu[aria-expanded="true"] {
  opacity: 1;
  visibility: visible;
}

.share-menu a {
  display: block;
  padding: var(--space-3) var(--space-4);
  color: var(--color-text-primary);
  text-decoration: none;
  font-size: var(--font-size-sm);
  transition: background-color var(--transition-fast);
  white-space: nowrap;
}

.share-menu a:hover,
.share-menu a:focus {
  background-color: var(--color-surface);
}

.share-menu a:first-child {
  border-radius: var(--radius-md) var(--radius-md) 0 0;
}

.share-menu a:last-child {
  border-radius: 0 0 var(--radius-md) var(--radius-md);
}

/* ==========================================================================
   Utility Classes
   ========================================================================== */

.visually-hidden {
  position: absolute !important;
  width: 1px !important;
  height: 1px !important;
  padding: 0 !important;
  margin: -1px !important;
  overflow: hidden !important;
  clip: rect(0, 0, 0, 0) !important;
  white-space: nowrap !important;
  border: 0 !important;
}

/* ==========================================================================
   Media Queries for Responsive Design
   ========================================================================== */

@media (max-width: 48rem) {
  .nav-menu {
    position: fixed;
    top: 4rem;
    left: 0;
    right: 0;
    background-color: white;
    border-bottom: 1px solid var(--color-border);
    flex-direction: column;
    padding: var(--space-4);
    gap: var(--space-4);
    transform: translateY(-100%);
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-normal);
  }
  
  .nav-menu[aria-expanded="true"] {
    transform: translateY(0);
    opacity: 1;
    visibility: visible;
  }
  
  .nav-toggle {
    display: block;
  }
  
  .article {
    padding: 0 var(--space-3);
  }
  
  .article-title {
    font-size: var(--font-size-3xl);
  }
  
  .article-content {
    font-size: var(--font-size-base);
  }
  
  .bio-container {
    flex-direction: column;
    text-align: center;
  }
  
  .bio-social {
    justify-content: center;
  }
  
  .social-sharing {
    position: static;
    transform: none;
    margin: var(--space-4) 0;
  }
  
  .share-toggle {
    writing-mode: horizontal-tb;
    margin-bottom: var(--space-2);
  }
  
  .share-menu {
    position: static;
    transform: none;
    opacity: 1;
    visibility: visible;
    margin: 0;
  }
  
  .footer-bottom {
    flex-direction: column;
    text-align: center;
  }
  
  .subscribe-form {
    flex-direction: column;
  }
}

@media (max-width: 30rem) {
  .article-meta {
    flex-direction: column;
    align-items: flex-start;
  }
  
  .author-info {
    width: 100%;
  }
  
  .related-grid {
    grid-template-columns: 1fr;
  }
  
  .footer-container {
    grid-template-columns: 1fr;
    text-align: center;
  }
  
  .social-links {
    justify-content: center;
  }
}

/* Print styles */
@media print {
  .header,
  .footer,
  .author-bio,
  .related-articles,
  .social-sharing {
    display: none;
  }
  
  .article {
    max-width: none;
    padding: 0;
  }
  
  .article-content {
    font-size: 12pt;
    line-height: 1.4;
  }
  
  a {
    color: inherit;
    text-decoration: underline;
  }
}