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

:root {
  /* Color Palette */
  --primary-color: #2563eb;
  --primary-dark: #1d4ed8;
  --secondary-color: #64748b;
  --accent-color: #f59e0b;
  --success-color: #10b981;
  --warning-color: #f59e0b;
  --danger-color: #ef4444;
  
  /* Neutral Colors */
  --white: #ffffff;
  --gray-50: #f8fafc;
  --gray-100: #f1f5f9;
  --gray-200: #e2e8f0;
  --gray-300: #cbd5e1;
  --gray-400: #94a3b8;
  --gray-500: #64748b;
  --gray-600: #475569;
  --gray-700: #334155;
  --gray-800: #1e293b;
  --gray-900: #0f172a;
  
  /* Element Colors */
  --hydrogen: #60a5fa;
  --alkali: #f472b6;
  --alkaline: #86efac;
  --transition-metal: #a78bfa;
  --post-transition: #fbbf24;
  --metalloid: #34d399;
  --nonmetal: #f87171;
  --noble-gas: #fbbf24;
  --lanthanide: #06b6d4;
  --actinide: #84cc16;
  --unknown: #9ca3af;
  
  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', 'SF Mono', Monaco, 'Cascadia Code', monospace;
  
  /* Spacing */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;
  --space-3xl: 4rem;
  
  /* Border Radius */
  --radius-sm: 0.25rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  
  /* Shadows */
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
  --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);
}

body {
  font-family: var(--font-sans);
  background: linear-gradient(135deg, var(--gray-50) 0%, var(--gray-100) 100%);
  color: var(--gray-900);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Header Styles */
.header {
  background: var(--white);
  border-bottom: 1px solid var(--gray-200);
  box-shadow: var(--shadow-sm);
  position: sticky;
  top: 0;
  z-index: 100;
}

.nav {
  max-width: 1200px;
  margin: 0 auto;
  padding: var(--space-md) var(--space-lg);
}

.nav-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.nav-brand {
  display: flex;
  align-items: center;
}

.nav-title {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--gray-900);
  margin: 0;
}

.nav-links {
  display: flex;
  gap: var(--space-lg);
}

.nav-link {
  display: inline-flex;
  align-items: center;
  padding: var(--space-sm) var(--space-md);
  color: var(--gray-600);
  text-decoration: none;
  font-weight: 500;
  border-radius: var(--radius-md);
  transition: all 0.2s ease;
}

.nav-link:hover {
  color: var(--primary-color);
  background: var(--gray-100);
}

.nav-link-text {
  font-size: 0.875rem;
}

/* Main Content */
.main {
  flex: 1;
  padding: var(--space-xl) 0;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

/* Hero Section */
.hero {
  text-align: center;
  margin-bottom: var(--space-3xl);
}

.hero-title {
  font-size: clamp(2rem, 5vw, 3.5rem);
  font-weight: 700;
  color: var(--gray-900);
  margin-bottom: var(--space-md);
  line-height: 1.2;
}

.hero-subtitle {
  font-size: 1.125rem;
  color: var(--gray-600);
  margin-bottom: var(--space-xl);
}

/* Periodic Table Container */
.periodic-table-container {
  background: var(--gray-900);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-lg);
  padding: var(--space-xl);
  margin-bottom: var(--space-2xl);
}

/* Periodic Table Grid */
.periodic-table {
  display: grid;
  grid-template-columns: repeat(18, 1fr);
  gap: 2px;
  padding: 0;
  list-style: none;
  counter-reset: element;
}

.periodic-table > li {
  display: flex;
  position: relative;
  justify-content: center;
  align-items: center;
  aspect-ratio: 1;
  border-radius: var(--radius-sm);
  background: var(--gray-800);
  color: var(--gray-50);
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  border: 1px solid var(--gray-700);
  transform: translateZ(0);
  will-change: transform, box-shadow, border-color;
}

.periodic-table > li:hover {
  transform: scale(1.15) translateZ(0);
  box-shadow: 
    0 0 0 2px var(--primary-color), 
    0 8px 32px 0 rgba(0,0,0,0.25),
    0 4px 16px 0 rgba(0,0,0,0.15);
  border-color: var(--primary-color);
  z-index: 20;
}

.periodic-table > li:active {
  transform: scale(1.05) translateZ(0);
  transition: transform 0.1s ease;
}

/* Add a subtle glow effect on hover */
.periodic-table > li::after {
  content: '';
  position: absolute;
  top: -2px;
  left: -2px;
  right: -2px;
  bottom: -2px;
  background: linear-gradient(45deg, var(--primary-color), var(--accent-color));
  border-radius: var(--radius-sm);
  opacity: 0;
  z-index: -1;
  transition: opacity 0.3s ease;
}

.periodic-table > li:hover::after {
  opacity: 0.3;
}

.periodic-table > li:before {
  counter-increment: element;
  content: counter(element);
  position: absolute;
  bottom: 2px;
  left: 2px;
  font-size: 0.5rem;
  font-weight: 400;
  color: var(--gray-400);
  font-family: var(--font-mono);
}

.periodic-table > li abbr {
  font-size: clamp(0.5rem, 1.5vw, 0.875rem);
  font-weight: 600;
  color: var(--gray-50);
  text-decoration: none;
  font-family: var(--font-mono);
}

/* Element Type Colors */
.periodic-table .hydrogen {
  background: #2563eb;
  color: #fff;
}

.periodic-table .alkali {
  background: #a21caf;
  color: #fff;
}

.periodic-table .alkaline {
  background: #15803d;
  color: #fff;
}

.periodic-table .noble-gas {
  background: #ca8a04;
  color: #fff;
}

.periodic-table .diatomic-nonmetal {
  background: #b91c1c;
  color: #fff;
}

.periodic-table .polyatomic-non-metal {
  background: #b91c1c;
  color: #fff;
}

.periodic-table .metalloid {
  background: #0d9488;
  color: #fff;
}

.periodic-table .lanthanide {
  background: #0369a1;
  color: #fff;
}

.periodic-table .actinide {
  background: #365314;
  color: #fff;
}

.periodic-table .unknown {
  background: #334155;
  color: #fff;
}

/* Periodic Table Layout Adjustments */
#helium {
  grid-column: 18;
}

#boron, #aluminium {
  grid-column: 13;
}

#cerium, #thorium {
  grid-column: 4;
}

.periodic-table > li:nth-child(n+58):nth-last-child(n+48) {
  grid-row: 8;
}

.periodic-table > li:nth-child(n+90):nth-last-child(n+16) {
  grid-row: 9;
}

.periodic-table:before {
  content: '';
  grid-row: 8 / 10;
  grid-column: 1 / 4;
}

/* Lightbox Styles */
#lightbox-overlay {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.8);
  backdrop-filter: blur(4px);
  justify-content: center;
  align-items: center;
  z-index: 1000;
  padding: var(--space-lg);
}

#lightbox-content {
  background: var(--white);
  padding: var(--space-xl);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-xl);
  max-width: 600px;
  width: 100%;
  max-height: 80vh;
  overflow-y: auto;
  text-align: left;
  font-size: 1rem;
  line-height: 1.6;
  color: var(--gray-900);
}

#lightbox-content h1,
#lightbox-content h2,
#lightbox-content h3 {
  color: var(--gray-900);
  margin-bottom: var(--space-md);
}

#lightbox-content p {
  margin-bottom: var(--space-md);
}

#lightbox-content a {
  color: var(--primary-color);
  text-decoration: none;
}

#lightbox-content a:hover {
  text-decoration: underline;
}

/* Footer */
.footer {
  background: var(--gray-900);
  color: var(--gray-300);
  padding: var(--space-lg) 0;
  margin-top: auto;
}

.footer-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--space-lg);
  text-align: center;
}

.footer-text {
  font-size: 0.875rem;
  margin: 0;
}

.footer-link {
  color: var(--accent-color);
  text-decoration: none;
  font-weight: 500;
}

.footer-link:hover {
  text-decoration: underline;
}

/* Responsive Design */
@media (max-width: 1200px) {
  .periodic-table {
    grid-template-columns: repeat(18, 1fr);
    gap: 1px;
  }
  
  .periodic-table > li abbr {
    font-size: clamp(0.4rem, 1.2vw, 0.75rem);
  }
}

@media (max-width: 768px) {
  .nav-container {
    flex-direction: column;
    gap: var(--space-md);
  }
  
  .nav-title {
    font-size: 1.25rem;
  }
  
  .hero {
    margin-bottom: var(--space-2xl);
  }
  
  .periodic-table-container {
    padding: var(--space-lg);
  }
  
  .periodic-table {
    grid-template-columns: repeat(9, 1fr);
    gap: 1px;
  }
  
  #helium, #boron, #aluminium, #cerium, #thorium {
    grid-column: auto;
  }
  
  .periodic-table > li:nth-child(n+58):nth-last-child(n+48),
  .periodic-table > li:nth-child(n+90):nth-last-child(n+16) {
    grid-row: auto;
  }
  
  .periodic-table:before {
    display: none;
  }
  
  .periodic-table > li abbr {
    font-size: clamp(0.6rem, 2vw, 0.875rem);
  }
  
  .periodic-table > li:before {
    font-size: 0.4rem;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 var(--space-md);
  }
  
  .periodic-table-container {
    padding: var(--space-md);
  }
  
  .periodic-table {
    grid-template-columns: repeat(6, 1fr);
  }
  
  .periodic-table > li abbr {
    font-size: clamp(0.5rem, 2.5vw, 0.75rem);
  }
  
  #lightbox-content {
    padding: var(--space-lg);
    margin: var(--space-md);
  }
}

/* Focus styles for accessibility */
.periodic-table > li:focus {
  outline: 2px solid var(--primary-color);
  outline-offset: 2px;
  transform: scale(1.1);
  box-shadow: 0 0 0 2px var(--primary-color), 0 6px 24px 0 rgba(0,0,0,0.18);
  z-index: 20;
}

/* Elements Table Styles */
.elements-table-container {
  margin-top: var(--space-3xl);
  padding: var(--space-lg);
  background: var(--white);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
}

.elements-table-title {
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--gray-900);
  margin-bottom: var(--space-lg);
  text-align: center;
}

.elements-table-wrapper {
  overflow-x: auto;
  border-radius: var(--radius-md);
  border: 1px solid var(--gray-200);
}

.elements-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.875rem;
}

.elements-table th {
  background: var(--gray-50);
  padding: var(--space-md);
  text-align: left;
  font-weight: 600;
  color: var(--gray-700);
  border-bottom: 2px solid var(--gray-200);
  position: sticky;
  top: 0;
  z-index: 10;
}

.elements-table td {
  padding: var(--space-md);
  border-bottom: 1px solid var(--gray-100);
  color: var(--gray-700);
  transition: all 0.2s ease;
}

.elements-table tbody tr {
  cursor: pointer;
  transition: all 0.2s ease;
}

.elements-table tbody tr:hover {
  background: var(--primary-color);
  color: var(--white);
}

.elements-table tbody tr:hover td {
  color: var(--white);
}

.elements-table .element-number {
  font-weight: 600;
  font-family: var(--font-mono);
  width: 80px;
}

.elements-table .element-name {
  font-weight: 500;
  min-width: 120px;
}

.elements-table .author-name {
  color: var(--gray-600);
  font-style: italic;
}

.elements-table tbody tr:hover .author-name {
  color: var(--gray-100);
}

/* About Page Styles */
.about-content {
  max-width: 800px;
  margin: 0 auto;
  padding: var(--space-lg) 0;
}

.about-section {
  margin-bottom: var(--space-2xl);
  padding: var(--space-lg);
  background: var(--white);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
  border: 1px solid var(--gray-200);
}

.about-section-title {
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--gray-900);
  margin-bottom: var(--space-md);
  border-bottom: 2px solid var(--primary-color);
  padding-bottom: var(--space-sm);
}

.about-text {
  font-size: 1rem;
  line-height: 1.7;
  color: var(--gray-700);
  margin-bottom: var(--space-md);
}

.about-text:last-child {
  margin-bottom: 0;
}

.about-link {
  color: var(--primary-color);
  text-decoration: none;
  font-weight: 500;
  transition: color 0.2s ease;
}

.about-link:hover {
  color: var(--primary-dark);
  text-decoration: underline;
}

.thumbnail-container {
  text-align: center;
  margin: var(--space-lg) 0;
}

.thumbnail {
  max-width: 300px;
  height: auto;
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-lg);
  cursor: pointer;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.thumbnail:hover {
  transform: scale(1.05);
  box-shadow: var(--shadow-xl);
}

/* About page lightbox styles */
#about-lightbox {
  background: rgba(0, 0, 0, 0.9);
  z-index: 1000;
}

#about-lightbox .lightbox-content {
  position: relative;
  max-width: 90vw;
  max-height: 90vh;
  background: var(--white);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
  box-shadow: var(--shadow-xl);
}

#about-lightbox .lightbox-content img {
  max-width: 100%;
  max-height: 80vh;
  border-radius: var(--radius-md);
  display: block;
  margin: 0 auto;
}

#about-lightbox .close-btn {
  position: absolute;
  top: var(--space-md);
  right: var(--space-md);
  background: var(--gray-100);
  border: none;
  border-radius: 50%;
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all 0.2s ease;
}

#about-lightbox .close-btn:hover {
  background: var(--gray-200);
  transform: scale(1.1);
}

/* Responsive about page styles */
@media (max-width: 768px) {
  .about-content {
    padding: var(--space-md) 0;
  }
  
  .about-section {
    padding: var(--space-md);
    margin-bottom: var(--space-xl);
  }
  
  .about-section-title {
    font-size: 1.25rem;
  }
  
  .about-text {
    font-size: 0.95rem;
  }
  
  .thumbnail {
    max-width: 250px;
  }
}

@media (max-width: 480px) {
  .about-section {
    padding: var(--space-sm);
    margin-bottom: var(--space-lg);
  }
  
  .about-section-title {
    font-size: 1.125rem;
  }
  
  .about-text {
    font-size: 0.9rem;
  }
  
  .thumbnail {
    max-width: 200px;
  }
}

/* Responsive table styles */
@media (max-width: 768px) {
  .elements-table-container {
    margin-top: var(--space-xl);
    padding: var(--space-md);
  }
  
  .elements-table-title {
    font-size: 1.25rem;
    margin-bottom: var(--space-md);
  }
  
  .elements-table {
    font-size: 0.75rem;
  }
  
  .elements-table th,
  .elements-table td {
    padding: var(--space-sm);
  }
  
  .elements-table .element-number {
    width: 60px;
  }
  
  .elements-table .element-name {
    min-width: 100px;
  }
}

@media (max-width: 480px) {
  .elements-table-container {
    padding: var(--space-sm);
  }
  
  .elements-table {
    font-size: 0.7rem;
  }
  
  .elements-table th,
  .elements-table td {
    padding: 0.5rem 0.25rem;
  }
  
  .elements-table .element-number {
    width: 50px;
  }
  
  .elements-table .element-name {
    min-width: 80px;
  }
}

/* Remove the pulse animation and fadeInUp for hover, keep only for initial load */
.element-fade-in {
  animation: fadeInUp 0.6s ease-out forwards;
  opacity: 0;
  transform: translateY(20px);
}

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

/* Print styles */
@media print {
  .header,
  .footer {
    display: none;
  }
  
  .periodic-table-container {
    box-shadow: none;
    border: 1px solid var(--gray-300);
  }
  
  .periodic-table > li {
    border: 1px solid var(--gray-300);
  }
}