/* Global styles */
:root {
  /* Water - Softer blue gradient */
  --water-primary: #64b5f6;
  --water-secondary: #1976d2;
  --water-accent: #bbdefb;
  --water-text: #e3f2fd;
  --water-background: linear-gradient(135deg, #81d4fa, #4fc3f7, #29b6f6);
  
  /* Fire - Softer red/orange gradient */
  --fire-primary: #ff8a65;
  --fire-secondary: #e64a19;
  --fire-accent: #ffccbc;
  --fire-text: #fff3e0;
  --fire-background: linear-gradient(135deg, #ffab91, #ff8a65, #ff7043);
  
  /* Earth - Softer green gradient */
  --earth-primary: #81c784;
  --earth-secondary: #388e3c;
  --earth-accent: #c8e6c9;
  --earth-text: #e8f5e9;
  --earth-background: linear-gradient(135deg, #a5d6a7, #81c784, #66bb6a);
  
  /* Wind - Softer gray/blue gradient */
  --wind-primary: #90a4ae;
  --wind-secondary: #546e7a;
  --wind-accent: #cfd8dc;
  --wind-text: #eceff1;
  --wind-background: linear-gradient(135deg, #b0bec5, #90a4ae, #78909c);
  
  /* New section divider colors */
  --section-divider: rgba(0, 0, 0, 0.1);
  --section-highlight: rgba(255, 255, 255, 0.1);
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Inter', 'Roboto', 'Helvetica Neue', Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  background-color: #fafbfc;
  color: #1f2937;
  line-height: 1.7;
  scroll-behavior: smooth;
  font-size: 16px;
  font-weight: 400;
  letter-spacing: -0.01em;
  padding-top: 0; /* body의 패딩은 제거하고 개별 컨테이너에서 처리 */
  overflow-x: hidden; /* 가로 스크롤 방지 */
  -webkit-overflow-scrolling: touch; /* iOS에서 부드러운 스크롤 */
  scroll-padding-top: 100px; /* 더 큰 스크롤 오프셋 */
}

a {
  text-decoration: none;
  color: inherit;
  transition: color 0.3s ease;
}

a:hover {
  text-decoration: underline;
}

/* Typography improvements */
h1, h2, h3, h4, h5, h6 {
  color: #111827;
  font-weight: 600;
  line-height: 1.3;
  margin-bottom: 1rem;
  text-rendering: optimizeLegibility;
}

p {
  margin-bottom: 1.2rem;
  line-height: 1.7;
  text-rendering: optimizeLegibility;
  color: #374151;
}

/* List styling improvements */
ul, ol {
  margin-bottom: 1.5rem;
  padding-left: 1.5rem;
}

ul li, ol li {
  margin-bottom: 0.75rem;
  line-height: 1.7;
  color: #374151;
  text-rendering: optimizeLegibility;
}

ul li {
  list-style-type: none;
  position: relative;
}

ul li::before {
  content: '•';
  color: #6366f1;
  font-weight: bold;
  position: absolute;
  left: -1.2rem;
  font-size: 1.1rem;
}

ol li {
  list-style-type: decimal;
  list-style-position: outside;
}

/* Nested lists */
ul ul, ol ol, ul ol, ol ul {
  margin-top: 0.5rem;
  margin-bottom: 0.5rem;
}

ul ul li::before {
  content: '◦';
  color: #8b5cf6;
}

/* Text elements */
strong, b {
  font-weight: 600;
  color: #111827;
}

em, i {
  font-style: italic;
  color: #4b5563;
}

.strong-blue {
  font-weight: 600;
  color: #1976d2;
}

code {
  background-color: transparent;
  padding: 0;
  border-radius: 0;
  font-family: 'Fira Code', 'JetBrains Mono', 'Monaco', 'Consolas', monospace;
  font-size: 0.875rem;
  color: #333;
  border: none;
}

/* Section styles */
.section {
  margin-bottom: 70px;
  padding-bottom: 45px;
  border-bottom: 1px solid var(--section-divider);
  animation: fadeIn 0.8s ease-in-out;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}

.section-title {
  font-size: 2.2rem;
  margin-bottom: 30px;
  position: relative;
  display: inline-block;
  font-weight: 700;
  color: #111827;
  letter-spacing: -0.025em;
}

.section-title::after {
  content: '';
  position: absolute;
  bottom: -8px;
  left: 0;
  width: 100%;
  height: 3px;
  border-radius: 1.5px;
  background: linear-gradient(90deg, currentColor, transparent);
}

/* Navigation styles */
.back-button {
  display: inline-flex;
  align-items: center;
  padding: 8px 16px;
  background-color: rgba(255, 255, 255, 0.2);
  color: inherit;
  text-decoration: none;
  border-radius: 4px;
  transition: all 0.3s;
  margin-bottom: 16px;
  backdrop-filter: blur(5px);
}

.back-button:hover {
  background-color: rgba(255, 255, 255, 0.3);
  transform: translateY(-2px);
}

.navigation-section {
  display: flex;
  justify-content: space-between;
  margin-top: 40px;
  padding: 20px 0;
}

.element-nav {
  padding: 12px 24px;
  border-radius: 8px;
  text-decoration: none;
  font-weight: 600;
  transition: transform 0.3s, box-shadow 0.3s;
  backdrop-filter: blur(5px);
}

.element-nav:hover {
  transform: translateY(-3px);
  box-shadow: 0 6px 12px rgba(0, 0, 0, 0.15);
  text-decoration: none;
}

/* Element-specific navigation buttons */
.element-nav.water {
  background-color: rgba(100, 181, 246, 0.8);
  color: var(--water-text);
}

.element-nav.fire {
  background-color: rgba(255, 138, 101, 0.8);
  color: var(--fire-text);
}

.element-nav.earth {
  background-color: rgba(129, 199, 132, 0.8);
  color: var(--earth-text);
}

.element-nav.wind {
  background-color: rgba(144, 164, 174, 0.8);
  color: var(--wind-text);
}

/* Sticky top navigation */
.sticky-nav {
  position: fixed !important; /* 강제로 고정 */
  top: 0 !important;
  left: 0 !important;
  right: 0 !important;
  width: 100% !important;
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  z-index: 1000;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
  padding: 15px 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  transition: all 0.3s ease;
  border-bottom: 1px solid rgba(0, 0, 0, 0.1);
  min-height: 60px; /* 최소 높이 설정으로 일관성 확보 */
  transform: translateZ(0); /* 하드웨어 가속 활성화 */
  will-change: transform; /* 최적화를 위한 힌트 제공 */
}

/* Enhanced PhysGaia Logo */
.nav-logo {
  margin-left: -15pt;
  padding-left: 0;
  font-size: 1.8rem;
  font-weight: 800;
  letter-spacing: -0.5px;
  background: linear-gradient(135deg, #1e88e5 0%, #e53935 25%, #43a047 50%, #78909c 75%, #1e88e5 100%);
  background-size: 200% 200%;
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  position: relative;
  display: flex;
  align-items: center;
  gap: 8px;
  transition: all 0.3s ease;
  cursor: pointer;
  text-decoration: none;
  animation: gradientShift 6s ease-in-out infinite;
}

.nav-logo::before {
  content: '🌱';
  font-size: 1.5rem;
  filter: drop-shadow(0 2px 4px rgba(0,0,0,0.1));
  animation: floatIcon 3s ease-in-out infinite;
}

.nav-logo::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 2.3rem; /* 아이콘 크기 + gap만큼 오프셋 */
  width: 0%;
  height: 2px;
  background: linear-gradient(90deg, #1e88e5, #e53935, #43a047, #78909c);
  transition: width 0.3s ease;
  border-radius: 1px;
}

.nav-logo:hover {
  transform: translateY(-1px);
  filter: drop-shadow(0 4px 8px rgba(0,0,0,0.1));
}

.nav-logo:hover::after {
  width: calc(100% - 2.3rem); /* 전체 너비에서 아이콘 부분 제외 */
}

@keyframes gradientShift {
  0%, 100% {
    background-position: 0% 50%;
  }
  50% {
    background-position: 100% 50%;
  }
}

@keyframes floatIcon {
  0%, 100% {
    transform: translateY(0px) rotate(0deg);
  }
  50% {
    transform: translateY(-2px) rotate(5deg);
  }
}

.sticky-nav.hidden {
  transform: translateY(-100%);
}

.sticky-nav .nav-links {
  display: flex;
  gap: 20px;
}

.sticky-nav .nav-link {
  padding: 8px 12px;
  border-radius: 4px;
  transition: background 0.3s;
}

.sticky-nav .nav-link:hover {
  background: rgba(0, 0, 0, 0.05);
  text-decoration: none;
}

.sticky-nav .nav-link.active {
  background: rgba(0, 0, 0, 0.1);
  font-weight: bold;
}

/* 16:9 aspect ratio */
/* Video container styles */
.video-container {
  width: 100%;
  max-width: 800px;
  margin: 0 auto 40px;
  border-radius: 12px;
  overflow: hidden;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.15);
  position: relative; /* This is crucial for positioning children */
  padding-bottom: 112.5%; /* 640:720 aspect ratio */
  height: 0; /* Ensures height is controlled by padding-bottom */
  transition: transform 0.3s ease;
}


.video-container img {
  position: absolute; /* Position the image relative to its parent (.video-container) */
  top: 0; /* Align to the top of the container */
  left: 0; /* Align to the left of the container */
  width: 100%; /* Make the image fill the full width of the container */
  height: 100%; /* Make the image fill the full height of the container */
  object-fit: cover; /* This will make sure the image covers the entire area without distortion, cropping if necessary */
}

.video-container:hover {
  transform: scale(1.01);
}

.video-container iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  border: 0;
}

/* Image carousel */
.image-carousel {
  position: relative;
  width: 100%;
  max-width: 800px;
  margin: 0 auto 40px;
  border-radius: 12px;
  overflow: hidden;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.15);
}

.carousel-container {
  display: flex;
  transition: transform 0.5s ease;
}

.carousel-slide {
  min-width: 100%;
  position: relative;
}

.carousel-slide img {
  width: 100%;
  height: auto;
  display: block;
}

.carousel-caption {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  background: rgba(0, 0, 0, 0.7);
  color: white;
  padding: 10px 20px;
  text-align: center;
}

.carousel-controls {
  position: absolute;
  top: 50%;
  width: 100%;
  display: flex;
  justify-content: space-between;
  transform: translateY(-50%);
}

.carousel-control {
  background: rgba(0, 0, 0, 0.5);
  color: white;
  border: none;
  border-radius: 50%;
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  margin: 0 10px;
  transition: background 0.3s;
}

.carousel-control:hover {
  background: rgba(0, 0, 0, 0.8);
}

.carousel-indicators {
  position: absolute;
  bottom: 10px;
  width: 100%;
  display: flex;
  justify-content: center;
  gap: 10px;
}

.carousel-indicator {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.5);
  cursor: pointer;
  transition: background 0.3s;
}

.carousel-indicator.active {
  background: white;
}

/* Description section styles */
.description-section {
  max-width: 900px;
  margin: 0 auto;
  padding: 45px;
  background-color: rgba(255, 255, 255, 0.97);
  border: 1px solid rgba(0, 0, 0, 0.08);
  border-radius: 16px;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
  backdrop-filter: blur(10px);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
  font-size: 16px;
  line-height: 1.75;
}

.description-section:hover {
  transform: translateY(-3px);
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.12);
}

.description-section h2 {
  margin-top: 0;
  margin-bottom: 28px;
  border-bottom: 2px solid rgba(25, 118, 210, 0.15);
  padding-bottom: 18px;
  font-size: 2.1rem;
  font-weight: 700;
  color: #111827;
  letter-spacing: -0.025em;
}

.description-section h3 {
  margin-top: 35px;
  margin-bottom: 18px;
  font-size: 1.5rem;
  font-weight: 600;
  color: #1f2937;
  letter-spacing: -0.02em;
}

.description-section ul {
  padding-left: 26px;
  margin-bottom: 26px;
}

.description-section li {
  margin-bottom: 14px;
  line-height: 1.8;
  color: #374151;
}

.description-section p {
  margin-bottom: 22px;
  font-size: 16px;
  line-height: 1.8;
  color: #1f2937;
  text-rendering: optimizeLegibility;
}

/* Abstract section styles moved to home.css to avoid duplication */

/* Container for element pages */
.element-container {
  min-height: 100vh;
  padding: 40px 20px;
}

.element-header {
  max-width: 1200px;
  margin: 0 auto 30px;
}

.element-header h1 {
  font-size: 2.5rem;
  margin: 20px 0;
  position: relative;
  display: inline-block;
  text-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.element-header h1::after {
  content: '';
  position: absolute;
  bottom: -10px;
  left: 0;
  width: 100%;
  height: 4px;
  border-radius: 2px;
}

.element-content {
  max-width: 1200px;
  margin: 0 auto;
}

/* BibTeX citation section */
.citation-section {
  margin-top: 40px;
  padding: 20px;
  background-color: rgba(255, 255, 255, 0.9);
  border-radius: 12px;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

.citation-section h2 {
  margin-top: 0;
  margin-bottom: 20px;
  font-size: 1.8rem;
}

.bibtex-container {
  background-color: #f5f5f5;
  border-radius: 8px;
  padding: 20px;
  overflow-x: auto;
  font-family: monospace;
  margin-bottom: 20px;
}

.copy-button {
  display: inline-block;
  padding: 8px 16px;
  background-color: #1976d2;
  color: white;
  border: none;
  border-radius: 4px;
  cursor: pointer;
  transition: background-color 0.3s;
}

.copy-button:hover {
  background-color: #0d47a1;
}

/* Water specific styles */
.water-container {
  background: var(--water-background);
  color: var(--water-text);
}

.water-container .element-header h1::after {
  background: var(--water-accent);
}

/* Fire specific styles */
.fire-container {
  background: var(--fire-background);
  color: var(--fire-text);
}

.fire-container .element-header h1::after {
  background: var(--fire-accent);
}

/* Earth specific styles */
.earth-container {
  background: var(--earth-background);
  color: var(--earth-text);
}

.earth-container .element-header h1::after {
  background: var(--earth-accent);
}

/* Wind specific styles */
.wind-container {
  background: var(--wind-background);
  color: var(--wind-text);
}

.wind-container .element-header h1::after {
  background: var(--wind-accent);
}

/* Comparison table */
.comparison-table {
  width: 100%;
  border-collapse: collapse;
  margin: 20px 0;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
  border-radius: 8px;
  overflow: hidden;
}

.comparison-table th,
.comparison-table td {
  padding: 12px 15px;
  text-align: left;
  border-bottom: 1px solid rgba(0, 0, 0, 0.1);
}

.comparison-table thead {
  background-color: rgba(0, 0, 0, 0.05);
  font-weight: bold;
}

.comparison-table tbody tr:nth-child(even) {
  background-color: rgba(0, 0, 0, 0.02);
}

.comparison-table tbody tr:hover {
  background-color: rgba(0, 0, 0, 0.05);
}

/* Method Diagram Section Styles */
/* The placeholder div that will become our grid container for the images */
.method-diagram {
  max-width: 1100px; /* Limits the overall width of the entire section */
  margin: 30px auto;
  border-radius: 8px;
  overflow: hidden; /* Hides any overflow of content */
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.15);

  /* New: Make teaser-container a Grid Container */
  display: grid;
  grid-template-columns: repeat(5, 1fr); /* 4 columns of equal width */
  gap: 15px; /* Space between the image items */
  padding: 10px; /* Padding inside the overall container */
  background-color: #f0f0f0; /* Optional: background for the container */
}

.method-image-item {
  display: flex;
  flex-direction: column;
  align-items: center;
}

.method-image-wrapper {
  position: relative;
  padding-bottom: 112.5%; /* Aspect ratio */
  width: 100%;
  height: 0;
  overflow: hidden;
  border-radius: 8px;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

.method-image-wrapper img {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.method-image-caption {
  font-size: 1em;
  color: #555;
  margin-top: 10px;
  text-align: center;
  line-height: 1.3;
}

/* Responsive design */
@media (max-width: 768px) {
  .navigation-section {
    flex-direction: column;
    gap: 16px;
  }
  
  .element-nav {
    text-align: center;
  }
  
  .element-header h1 {
    font-size: 2rem;
  }
  
  .sticky-nav {
    padding: 10px 15px;
    min-height: 50px;
    position: fixed !important; /* 모바일에서도 강제로 고정 */
    top: 0 !important;
    left: 0 !important;
    right: 0 !important;
    width: 100% !important;
  }
  
  .sticky-nav .nav-links {
    gap: 8px;
  }
  
  .sticky-nav .nav-link {
    padding: 4px 6px;
    font-size: 0.85rem;
  }
  
  .section-title {
    font-size: 1.6rem;
  }
}

/* Lightbox */
.lightbox {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.9);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 2000;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s ease;
}

.lightbox.active {
  opacity: 1;
  pointer-events: auto;
}

.lightbox-content {
  max-width: 90%;
  max-height: 90%;
}

.lightbox-content img {
  max-width: 100%;
  max-height: 100%;
  display: block;
}

.lightbox-close {
  position: absolute;
  top: 20px;
  right: 20px;
  color: white;
  font-size: 2rem;
  cursor: pointer;
}

/* Animation for section transitions */
.animate-in {
  animation: fadeInUp 0.6s ease forwards;
  opacity: 1; /* Changed from 0 to 1 to ensure visibility */
  transition: opacity 0.6s ease, transform 0.6s ease;
}

/* Special case for contact section - always visible */
#contact.animate-in {
  opacity: 1 !important;
  transform: translateY(0) !important;
}

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

/* Delayed animations for sequential elements */
.delay-1 { animation-delay: 0.1s; }
.delay-2 { animation-delay: 0.2s; }
.delay-3 { animation-delay: 0.3s; }
.delay-4 { animation-delay: 0.4s; }
.delay-5 { animation-delay: 0.5s; }