/* ============================================
   MODERN NEWS AGGREGATOR - DESIGN SYSTEM
   ============================================ */

:root {
  /* Color System - Vibrant & Professional */
  --primary-hue: 210;
  --accent-hue: 280;
  
  /* Light Theme */
  --bg-primary: hsl(0, 0%, 98%);
  --bg-secondary: hsl(0, 0%, 100%);
  --bg-tertiary: hsl(var(--primary-hue), 30%, 96%);
  --text-primary: hsl(0, 0%, 10%);
  --text-secondary: hsl(0, 0%, 35%);
  --text-tertiary: hsl(0, 0%, 55%);
  
  /* Accent Colors */
  --accent-primary: hsl(var(--primary-hue), 85%, 55%);
  --accent-secondary: hsl(var(--accent-hue), 75%, 60%);
  --accent-gradient: linear-gradient(135deg, 
    hsl(var(--primary-hue), 85%, 55%) 0%, 
    hsl(var(--accent-hue), 75%, 60%) 100%);
  
  /* Semantic Colors */
  --success: hsl(145, 65%, 50%);
  --warning: hsl(40, 95%, 55%);
  --error: hsl(5, 75%, 55%);
  
  /* Shadows & Effects */
  --shadow-sm: 0 2px 8px hsla(0, 0%, 0%, 0.06);
  --shadow-md: 0 4px 16px hsla(0, 0%, 0%, 0.08);
  --shadow-lg: 0 8px 32px hsla(0, 0%, 0%, 0.12);
  --shadow-glow: 0 0 40px hsla(var(--accent-hue), 75%, 60%, 0.2);
  
  /* Glass Effect */
  --glass-bg: hsla(0, 0%, 100%, 0.7);
  --glass-border: hsla(0, 0%, 100%, 0.3);
  
  /* Spacing */
  --space-xs: 0.5rem;
  --space-sm: 1rem;
  --space-md: 1.5rem;
  --space-lg: 2.5rem;
  --space-xl: 4rem;
  
  /* Typography */
  --font-primary: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif;
  --font-weight-normal: 400;
  --font-weight-medium: 500;
  --font-weight-semibold: 600;
  --font-weight-bold: 700;
  
  /* Border Radius */
  --radius-sm: 0.5rem;
  --radius-md: 1rem;
  --radius-lg: 1.5rem;
  --radius-full: 9999px;
  
  /* Transitions */
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-normal: 300ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 500ms cubic-bezier(0.4, 0, 0.2, 1);
  
  /* Layout */
  --max-width: 1400px;
  --header-height: 80px;
}

/* Dark Theme */
[data-theme="dark"] {
  --bg-primary: hsl(220, 15%, 8%);
  --bg-secondary: hsl(220, 15%, 12%);
  --bg-tertiary: hsl(220, 15%, 16%);
  --text-primary: hsl(0, 0%, 95%);
  --text-secondary: hsl(0, 0%, 75%);
  --text-tertiary: hsl(0, 0%, 55%);
  
  --glass-bg: hsla(220, 15%, 15%, 0.7);
  --glass-border: hsla(0, 0%, 100%, 0.1);
  
  --shadow-sm: 0 2px 8px hsla(0, 0%, 0%, 0.3);
  --shadow-md: 0 4px 16px hsla(0, 0%, 0%, 0.4);
  --shadow-lg: 0 8px 32px hsla(0, 0%, 0%, 0.5);
}

/* ============================================
   BASE STYLES
   ============================================ */

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

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

body {
  font-family: var(--font-primary);
  font-weight: var(--font-weight-normal);
  line-height: 1.6;
  color: var(--text-primary);
  background: var(--bg-primary);
  transition: background var(--transition-normal), color var(--transition-normal);
  overflow-x: hidden;
}

/* ============================================
   TYPOGRAPHY
   ============================================ */

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

h1 { font-size: 3rem; }
h2 { font-size: 2.25rem; }
h3 { font-size: 1.75rem; }
h4 { font-size: 1.5rem; }
h5 { font-size: 1.25rem; }
h6 { font-size: 1rem; }

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

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

a:hover {
  color: var(--accent-secondary);
}

/* ============================================
   HEADER & NAVIGATION
   ============================================ */

.header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: var(--glass-bg);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--glass-border);
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-normal);
}

.header-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: var(--space-md) var(--space-lg);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-lg);
}

.logo {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-size: 1.5rem;
  font-weight: var(--font-weight-bold);
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  cursor: pointer;
}

.logo-icon {
  width: 40px;
  height: 40px;
  background: var(--accent-gradient);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-size: 1.5rem;
}

.header-controls {
  display: flex;
  align-items: center;
  gap: var(--space-md);
}

.search-container {
  position: relative;
  flex: 1;
  max-width: 500px;
}

.search-input {
  width: 100%;
  padding: var(--space-sm) var(--space-md);
  padding-left: 3rem;
  background: var(--bg-tertiary);
  border: 2px solid transparent;
  border-radius: var(--radius-full);
  font-size: 1rem;
  color: var(--text-primary);
  transition: all var(--transition-normal);
}

.search-input:focus {
  outline: none;
  border-color: var(--accent-primary);
  background: var(--bg-secondary);
  box-shadow: var(--shadow-glow);
}

.search-icon {
  position: absolute;
  left: 1rem;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-tertiary);
  pointer-events: none;
}

.theme-toggle {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-full);
  background: var(--bg-tertiary);
  border: none;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.25rem;
  transition: all var(--transition-normal);
}

.theme-toggle:hover {
  background: var(--accent-gradient);
  transform: scale(1.1) rotate(15deg);
  box-shadow: var(--shadow-glow);
}

/* ============================================
   MAIN CONTENT
   ============================================ */

.main-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: var(--space-lg);
  min-height: calc(100vh - var(--header-height));
}

.hero-section {
  text-align: center;
  padding: var(--space-xl) 0;
  margin-bottom: var(--space-lg);
}

.hero-title {
  font-size: clamp(2rem, 5vw, 4rem);
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  margin-bottom: var(--space-md);
  animation: fadeInUp 0.8s ease;
}

.hero-subtitle {
  font-size: 1.25rem;
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto;
  animation: fadeInUp 0.8s ease 0.2s both;
}

/* ============================================
   NEWS GRID
   ============================================ */

.news-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
  gap: var(--space-lg);
  margin-bottom: var(--space-xl);
}

.news-card {
  background: var(--bg-secondary);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-md);
  transition: all var(--transition-normal);
  cursor: pointer;
  animation: fadeInUp 0.6s ease both;
  position: relative;
}

.news-card:hover {
  transform: translateY(-8px);
  box-shadow: var(--shadow-lg), var(--shadow-glow);
}

.news-image-container {
  position: relative;
  width: 100%;
  padding-top: 56.25%; /* 16:9 aspect ratio */
  background: var(--bg-tertiary);
  overflow: hidden;
}

.news-image {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform var(--transition-slow);
}

.news-card:hover .news-image {
  transform: scale(1.05);
}

.news-content {
  padding: var(--space-md);
}

.news-meta {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  margin-bottom: var(--space-sm);
  font-size: 0.875rem;
  color: var(--text-tertiary);
}

.news-source {
  font-weight: var(--font-weight-semibold);
  color: var(--accent-primary);
}

.news-date {
  display: flex;
  align-items: center;
  gap: 0.25rem;
}

.news-title {
  font-size: 1.25rem;
  font-weight: var(--font-weight-semibold);
  color: var(--text-primary);
  margin-bottom: var(--space-sm);
  line-height: 1.4;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.news-description {
  color: var(--text-secondary);
  font-size: 0.95rem;
  line-height: 1.6;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
  margin-bottom: var(--space-md);
}

.news-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: var(--space-sm);
  border-top: 1px solid var(--glass-border);
}

.read-more {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--accent-primary);
  font-weight: var(--font-weight-medium);
  transition: gap var(--transition-fast);
}

.news-card:hover .read-more {
  gap: 0.75rem;
}

/* ============================================
   LOADING & EMPTY STATES
   ============================================ */

.loading-container {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: var(--space-xl) 0;
  min-height: 400px;
}

.loader {
  width: 60px;
  height: 60px;
  border: 4px solid var(--bg-tertiary);
  border-top: 4px solid var(--accent-primary);
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

.loading-text {
  margin-top: var(--space-md);
  color: var(--text-secondary);
  font-weight: var(--font-weight-medium);
}

.empty-state {
  text-align: center;
  padding: var(--space-xl) 0;
  color: var(--text-secondary);
}

.empty-icon {
  font-size: 4rem;
  margin-bottom: var(--space-md);
  opacity: 0.5;
}

.error-message {
  background: hsla(5, 75%, 55%, 0.1);
  border: 1px solid var(--error);
  border-radius: var(--radius-md);
  padding: var(--space-md);
  margin-bottom: var(--space-lg);
  color: var(--error);
  text-align: center;
}

/* ============================================
   AD PLACEHOLDERS
   ============================================ */

.ad-container {
  background: var(--bg-tertiary);
  border-radius: var(--radius-md);
  padding: var(--space-lg);
  margin: var(--space-lg) 0;
  text-align: center;
  border: 2px dashed var(--glass-border);
  min-height: 250px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-tertiary);
  font-size: 0.875rem;
}

.ad-leaderboard {
  min-height: 90px;
}

.ad-square {
  min-height: 250px;
}

.ad-sidebar {
  position: sticky;
  top: calc(var(--header-height) + var(--space-lg));
}

/* ============================================
   FOOTER
   ============================================ */

.footer {
  background: var(--bg-secondary);
  border-top: 1px solid var(--glass-border);
  padding: var(--space-xl) var(--space-lg);
  text-align: center;
  color: var(--text-secondary);
  margin-top: var(--space-xl);
}

.footer-content {
  max-width: var(--max-width);
  margin: 0 auto;
}

.footer-text {
  margin-bottom: var(--space-sm);
}

.footer-links {
  display: flex;
  justify-content: center;
  gap: var(--space-md);
  flex-wrap: wrap;
}

/* ============================================
   ANIMATIONS
   ============================================ */

@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

/* ============================================
   RESPONSIVE DESIGN
   ============================================ */

@media (max-width: 768px) {
  :root {
    --space-lg: 1.5rem;
    --space-xl: 2.5rem;
  }
  
  h1 { font-size: 2rem; }
  h2 { font-size: 1.75rem; }
  
  .header-container {
    flex-direction: column;
    gap: var(--space-md);
    padding: var(--space-md);
  }
  
  .search-container {
    max-width: 100%;
    width: 100%;
  }
  
  .news-grid {
    grid-template-columns: 1fr;
    gap: var(--space-md);
  }
  
  .hero-section {
    padding: var(--space-lg) 0;
  }
}

@media (max-width: 480px) {
  .main-container {
    padding: var(--space-md);
  }
  
  .logo {
    font-size: 1.25rem;
  }
  
  .logo-icon {
    width: 32px;
    height: 32px;
  }
}

/* ============================================
   UTILITY CLASSES
   ============================================ */

.hidden {
  display: none !important;
}

.fade-in {
  animation: fadeInUp 0.6s ease both;
}

.text-gradient {
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}