/* ========================================
   Modern Academic Design System
   VLCS@SCU - Future-Ready Styling
   ======================================== */

:root {
  /* Color Palette - Future Tech */
  --primary-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  --secondary-gradient: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
  --accent-gradient: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
  --dark-gradient: linear-gradient(135deg, #1e3c72 0%, #2a5298 100%);
  
  --primary-color: #667eea;
  --secondary-color: #764ba2;
  --accent-color: #4facfe;
  --text-primary: #1a202c;
  --text-secondary: #4a5568;
  --text-muted: #718096;
  --bg-light: #f7fafc;
  --bg-card: #ffffff;
  --border-color: #e2e8f0;
  
  /* Spacing */
  --spacing-xs: 0.5rem;
  --spacing-sm: 1rem;
  --spacing-md: 1.5rem;
  --spacing-lg: 2rem;
  --spacing-xl: 3rem;
  
  /* Typography */
  --font-primary: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  --font-mono: 'SF Mono', 'Monaco', 'Inconsolata', 'Fira Code', monospace;
  
  /* Effects */
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.07);
  --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.1);
  --shadow-xl: 0 20px 40px rgba(0, 0, 0, 0.15);
  --shadow-glow: 0 0 20px rgba(102, 126, 234, 0.3);
  
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 1rem;
  --radius-xl: 1.5rem;
  
  --transition-fast: 0.15s ease;
  --transition-base: 0.3s ease;
  --transition-slow: 0.5s ease;
}

/* ========================================
   Base Styles
   ======================================== */

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: 80px;
}

body {
  font-family: var(--font-primary);
  color: var(--text-primary);
  background: var(--bg-light);
  padding-top: 80px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* ========================================
   Typography
   ======================================== */

h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: 1.3;
  letter-spacing: -0.02em;
  color: var(--text-primary);
}

h1 {
  font-size: clamp(2rem, 5vw, 3.5rem);
  background: var(--primary-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

h2 {
  font-size: clamp(1.5rem, 4vw, 2.5rem);
}

h3 {
  font-size: clamp(1.25rem, 3vw, 2rem);
}

p {
  color: var(--text-secondary);
  margin-bottom: 1rem;
}

.lead {
  font-size: 1.25rem;
  font-weight: 300;
  color: var(--text-secondary);
}

/* ========================================
   Links
   ======================================== */

a {
  color: var(--primary-color);
  text-decoration: none;
  transition: all var(--transition-base);
  position: relative;
}

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

.non-decoration-link a {
  text-decoration: none;
  position: relative;
}

.non-decoration-link a::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--primary-gradient);
  transition: width var(--transition-base);
}

.non-decoration-link a:hover::after {
  width: 100%;
}

.non-decoration-link a:hover {
  color: var(--primary-color);
}

/* ========================================
   Cards & Containers
   ======================================== */

.card-modern {
  background: var(--bg-card);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
  padding: var(--spacing-lg);
  transition: all var(--transition-base);
  border: 1px solid var(--border-color);
  position: relative;
  overflow: hidden;
}

.card-modern::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: var(--primary-gradient);
  transform: scaleX(0);
  transition: transform var(--transition-base);
}

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

.card-modern:hover::before {
  transform: scaleX(1);
}

/* ========================================
   Buttons
   ======================================== */

.btn-modern {
  padding: 0.75rem 2rem;
  border-radius: var(--radius-md);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  transition: all var(--transition-base);
  border: none;
  cursor: pointer;
  position: relative;
  overflow: hidden;
}

.btn-gradient {
  background: var(--primary-gradient);
  color: white;
  box-shadow: var(--shadow-md);
}

.btn-gradient:hover {
  box-shadow: var(--shadow-lg), var(--shadow-glow);
  transform: translateY(-2px);
  color: white;
}

.btn-gradient::before {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255,255,255,0.3), transparent);
  transition: left 0.5s;
}

.btn-gradient:hover::before {
  left: 100%;
}

/* ========================================
   Navigation
   ======================================== */

.navbar-modern {
  background: rgba(255, 255, 255, 0.95) !important;
  backdrop-filter: blur(10px);
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-base);
}

.navbar-modern.scrolled {
  box-shadow: var(--shadow-md);
}

.nav-link {
  position: relative;
  font-weight: 500;
  color: var(--text-primary) !important;
  padding: 0.5rem 1rem !important;
  transition: all var(--transition-base);
}

.nav-link::before {
  content: '';
  position: absolute;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 0;
  height: 3px;
  background: var(--primary-gradient);
  border-radius: 2px;
  transition: width var(--transition-base);
}

.nav-link:hover::before,
.nav-link.active::before {
  width: 80%;
}

.navbar-brand {
  font-weight: 700;
  font-size: 1.5rem;
  background: var(--primary-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* ========================================
   Catalog / TOC
   ======================================== */

#catalog {
  background: var(--bg-card);
  border-radius: var(--radius-lg);
  padding: var(--spacing-md);
  box-shadow: var(--shadow-md);
  position: sticky;
  top: 100px;
}

#catalog li {
  list-style: none;
  line-height: 2;
  font-size: 0.9rem;
  padding: 0.5rem 1rem;
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
  position: relative;
}

#catalog li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 50%;
  transform: translateY(-50%);
  width: 3px;
  height: 0;
  background: var(--primary-gradient);
  border-radius: 2px;
  transition: height var(--transition-base);
}

#catalog li:hover {
  background: linear-gradient(90deg, rgba(102, 126, 234, 0.1), transparent);
  padding-left: 1.5rem;
}

#catalog li:hover::before {
  height: 70%;
}

#catalog li.current {
  font-weight: 600;
  color: var(--primary-color);
  background: linear-gradient(90deg, rgba(102, 126, 234, 0.15), transparent);
  padding-left: 1.5rem;
}

#catalog li.current::before {
  height: 70%;
}

#catalog a {
  color: inherit;
  text-decoration: none;
}

/* ========================================
   Blockquotes
   ======================================== */

blockquote {
  padding: var(--spacing-md);
  margin: var(--spacing-lg) 0;
  background: linear-gradient(135deg, rgba(102, 126, 234, 0.05), rgba(118, 75, 162, 0.05));
  border-left: 4px solid;
  border-image: var(--primary-gradient) 1;
  border-radius: var(--radius-md);
  font-style: italic;
  color: var(--text-secondary);
  position: relative;
}

blockquote::before {
  content: '"';
  position: absolute;
  top: -10px;
  left: 10px;
  font-size: 4rem;
  color: var(--primary-color);
  opacity: 0.2;
  font-family: Georgia, serif;
}

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

footer {
  background: var(--dark-gradient);
  color: rgba(255, 255, 255, 0.9);
  padding: var(--spacing-xl) 0;
  margin-top: var(--spacing-xl);
  position: relative;
  overflow: hidden;
}

footer::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, rgba(255,255,255,0.3), transparent);
}

footer p {
  color: rgba(255, 255, 255, 0.8);
  margin: 0;
}

footer a {
  color: rgba(255, 255, 255, 0.9);
  transition: all var(--transition-base);
}

footer a:hover {
  color: white;
  text-shadow: 0 0 10px rgba(255, 255, 255, 0.5);
}

/* ========================================
   Animations
   ======================================== */

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

@keyframes float {
  0%, 100% {
    transform: translateY(0);
  }
  50% {
    transform: translateY(-10px);
  }
}

@keyframes pulse {
  0%, 100% {
    opacity: 1;
  }
  50% {
    opacity: 0.5;
  }
}

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

.float-animation {
  animation: float 3s ease-in-out infinite;
}

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

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

.glass-effect {
  background: rgba(255, 255, 255, 0.7);
  backdrop-filter: blur(10px);
  border: 1px solid rgba(255, 255, 255, 0.3);
}

.section-divider {
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--border-color), transparent);
  margin: var(--spacing-xl) 0;
}

/* ========================================
   Responsive Design
   ======================================== */

@media (max-width: 768px) {
  body {
    padding-top: 70px;
  }
  
  .card-modern {
    padding: var(--spacing-md);
  }
  
  #catalog {
    position: static;
    margin-bottom: var(--spacing-lg);
  }
}

/* ========================================
   News Images - Responsive & Modal
   ======================================== */

.markdown-content img {
  max-width: 100%;
  height: auto;
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-md);
  cursor: pointer;
  transition: all var(--transition-base);
  margin: var(--spacing-md) 0;
  display: block;
}

.markdown-content img:hover {
  transform: scale(1.02);
  box-shadow: var(--shadow-lg);
}

/* Image Modal Styles */
.image-modal {
  display: none;
  position: fixed;
  z-index: 9999;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.9);
  animation: fadeIn 0.3s ease;
}

.image-modal.active {
  display: flex;
  align-items: center;
  justify-content: center;
}

.image-modal-content {
  max-width: 90%;
  max-height: 90%;
  object-fit: contain;
  border-radius: var(--radius-lg);
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.5);
  animation: zoomIn 0.3s ease;
}

.image-modal-close {
  position: absolute;
  top: 20px;
  right: 40px;
  color: white;
  font-size: 40px;
  font-weight: bold;
  cursor: pointer;
  transition: all var(--transition-base);
  z-index: 10000;
  width: 50px;
  height: 50px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(255, 255, 255, 0.1);
  border-radius: 50%;
  backdrop-filter: blur(10px);
}

.image-modal-close:hover {
  background: rgba(255, 255, 255, 0.2);
  transform: rotate(90deg);
}

.image-modal-caption {
  position: absolute;
  bottom: 30px;
  left: 50%;
  transform: translateX(-50%);
  color: white;
  text-align: center;
  padding: 1rem 2rem;
  background: rgba(0, 0, 0, 0.7);
  border-radius: var(--radius-md);
  backdrop-filter: blur(10px);
  max-width: 80%;
}

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

@keyframes zoomIn {
  from {
    transform: scale(0.8);
    opacity: 0;
  }
  to {
    transform: scale(1);
    opacity: 1;
  }
}

/* Mobile responsive */
@media (max-width: 768px) {
  .image-modal-close {
    top: 10px;
    right: 10px;
    font-size: 30px;
    width: 40px;
    height: 40px;
  }
  
  .image-modal-content {
    max-width: 95%;
    max-height: 85%;
  }
  
  .image-modal-caption {
    bottom: 10px;
    padding: 0.75rem 1rem;
    font-size: 0.9rem;
    max-width: 90%;
  }
}

/* ========================================
   Accessibility
   ======================================== */

:focus-visible {
  outline: 3px solid var(--primary-color);
  outline-offset: 2px;
}

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