:root {
  /* Brand Colors */
  --primary: #2563eb;
  --primary-dark: #1e40af;
  --primary-light: #eff6ff;
  --secondary: #7c3aed;
  --secondary-dark: #6d28d9;
  --accent: #10b981;
  --accent-light: #d1fae5;
  --warning: #f59e0b;
  --danger: #ef4444;
  
  /* Neutral Colors */
  --bg-main: #f8fafc;
  --bg-card: #ffffff;
  --bg-hover: #f1f5f9;
  --text-main: #0f172a;
  --text-secondary: #334155;
  --text-muted: #64748b;
  --border-color: #e2e8f0;
  --border-focus: #2563eb;
  
  /* Shadows */
  --shadow-xs: 0 1px 2px 0 rgb(0 0 0 / 0.03);
  --shadow-sm: 0 1px 3px 0 rgb(0 0 0 / 0.05);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.08);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1);
  --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.12);
  
  /* Border Radius */
  --radius-sm: 0.5rem;
  --radius-md: 0.75rem;
  --radius-lg: 1rem;
  --radius-xl: 1.5rem;
  --radius-full: 9999px;
  
  /* Spacing */
  --spacing-xs: 0.5rem;
  --spacing-sm: 1rem;
  --spacing-md: 1.5rem;
  --spacing-lg: 2rem;
  --spacing-xl: 3rem;
  
  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'Fira Code', 'Courier New', monospace;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  background: linear-gradient(135deg, #f8fafc 0%, #f1f5f9 100%);
  color: var(--text-main);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

.layout {
  display: flex;
  min-height: 100vh;
  background: var(--bg-main);
}

/* Enhanced Sidebar */
.sidebar {
  width: 280px;
  background: linear-gradient(180deg, #ffffff 0%, #f8fafc 100%);
  border-right: 1px solid var(--border-color);
  padding: var(--spacing-lg) var(--spacing-md);
  flex-shrink: 0;
  box-shadow: var(--shadow-sm);
  position: sticky;
  top: 0;
  height: 100vh;
  overflow-y: auto;
}

.logo {
  font-weight: 800;
  font-size: 1.75rem;
  background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  margin-bottom: var(--spacing-xl);
  display: flex;
  align-items: center;
  gap: 0.75rem;
  letter-spacing: -0.02em;
}

.logo i {
  background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
  padding: 0.75rem;
  border-radius: var(--radius-lg);
  color: white;
  box-shadow: var(--shadow-md);
}

.nav-link {
  display: flex;
  align-items: center;
  gap: 0.875rem;
  padding: 1rem 1.25rem;
  text-decoration: none;
  color: var(--text-secondary);
  font-weight: 500;
  border-radius: var(--radius-md);
  margin-bottom: 0.5rem;
  transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
  position: relative;
  overflow: hidden;
}

.nav-link::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0;
  height: 100%;
  width: 3px;
  background: var(--primary);
  transform: scaleY(0);
  transition: transform 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

.nav-link:hover {
  background: var(--bg-hover);
  color: var(--primary);
  transform: translateX(4px);
}

.nav-link:hover::before {
  transform: scaleY(1);
}

.nav-link.active {
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
  color: white;
  box-shadow: var(--shadow-md);
}

.nav-link.active::before {
  transform: scaleY(1);
  background: white;
}

/* Main Content */
.main-content {
  flex: 1;
  padding: var(--spacing-xl);
  max-width: 1400px;
  margin: 0 auto;
  width: 100%;
}

/* Header */
.header {
  margin-bottom: var(--spacing-xl);
  animation: fadeInDown 0.6s ease;
}

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

.welcome-msg {
  font-size: 2.5rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  margin-bottom: 0.75rem;
  background: linear-gradient(135deg, var(--text-main) 0%, var(--text-secondary) 100%);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.subtitle {
  color: var(--text-muted);
  font-size: 1.125rem;
  max-width: 700px;
}

/* Enhanced Grid */
.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: var(--spacing-lg);
  animation: fadeInUp 0.6s ease 0.2s both;
}

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

/* Premium Cards */
.card {
  background: white;
  border-radius: var(--radius-xl);
  padding: var(--spacing-lg);
  border: 1px solid var(--border-color);
  box-shadow: var(--shadow-sm);
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  position: relative;
  overflow: hidden;
}

.card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--primary) 0%, var(--secondary) 100%);
  transform: scaleX(0);
  transition: transform 0.3s ease;
}

.card:hover {
  transform: translateY(-8px);
  box-shadow: var(--shadow-xl);
  border-color: var(--primary-light);
}

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

.card-title {
  font-size: 1.375rem;
  font-weight: 700;
  margin-bottom: var(--spacing-sm);
  color: var(--text-main);
}

.card-desc {
  color: var(--text-muted);
  margin-bottom: var(--spacing-lg);
  font-size: 0.95rem;
  line-height: 1.7;
}

/* Enhanced Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.875rem 1.75rem;
  border-radius: var(--radius-md);
  font-weight: 600;
  font-size: 0.95rem;
  text-decoration: none;
  text-align: center;
  transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
  cursor: pointer;
  border: none;
  position: relative;
  overflow: hidden;
}

.btn::before {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  width: 0;
  height: 0;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.3);
  transform: translate(-50%, -50%);
  transition: width 0.6s, height 0.6s;
}

.btn:hover::before {
  width: 300px;
  height: 300px;
}

.btn-primary {
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
  color: white;
  box-shadow: var(--shadow-md);
}

.btn-primary:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-2px);
}

.btn-primary:active {
  transform: translateY(0);
}

/* Systems Page */
.systems-container {
    display: flex;
    gap: var(--spacing-lg);
    height: calc(100vh - 12rem);
}

.system-list {
    width: 340px;
    overflow-y: auto;
    padding-right: var(--spacing-sm);
}

.system-list::-webkit-scrollbar {
    width: 6px;
}

.system-list::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: var(--radius-full);
}

.system-item {
    background: white;
    padding: var(--spacing-md);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
    margin-bottom: var(--spacing-sm);
    cursor: pointer;
    transition: all 0.25s ease;
    position: relative;
}

.system-item::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    height: 100%;
    width: 4px;
    background: var(--primary);
    border-radius: var(--radius-lg) 0 0 var(--radius-lg);
    opacity: 0;
    transition: opacity 0.25s ease;
}

.system-item:hover {
    border-color: var(--primary);
    box-shadow: var(--shadow-md);
    transform: translateX(4px);
}

.system-item:hover::before {
    opacity: 1;
}

.system-item.active {
    border-color: var(--primary);
    background: var(--primary-light);
    box-shadow: var(--shadow-md);
}

.system-item.active::before {
    opacity: 1;
}

.system-detail {
    flex: 1;
    background: white;
    border-radius: var(--radius-xl);
    border: 1px solid var(--border-color);
    padding: var(--spacing-xl);
    overflow-y: auto;
    box-shadow: var(--shadow-sm);
}

.system-detail::-webkit-scrollbar {
    width: 8px;
}

.system-detail::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: var(--radius-full);
}

.section-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-lg);
    margin-top: var(--spacing-lg);
}

.detail-section {
    background: linear-gradient(135deg, #f8fafc 0%, #f1f5f9 100%);
    padding: var(--spacing-md);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
    transition: all 0.3s ease;
}

.detail-section:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-4px);
}

.detail-section h4 {
    margin-bottom: var(--spacing-sm);
    color: var(--primary);
    text-transform: uppercase;
    font-size: 0.75rem;
    letter-spacing: 0.05em;
    font-weight: 800;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

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

.detail-section li {
    font-size: 0.9rem;
    margin-bottom: 0.75rem;
    position: relative;
    padding-left: 1.5rem;
    line-height: 1.6;
}

.detail-section li::before {
    content: "✓";
    position: absolute;
    left: 0;
    color: var(--accent);
    font-weight: bold;
    font-size: 1.1rem;
}

/* Footer */
.footer {
    margin-top: auto;
    padding: var(--spacing-lg);
    border-top: 1px solid var(--border-color);
    text-align: center;
    color: var(--text-muted);
    font-size: 0.875rem;
}

.footer a {
    color: var(--primary);
    text-decoration: none;
    font-weight: 600;
}

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

/* Print Styles */
@media print {
    .sidebar,
    .btn {
        display: none;
    }
    
    .main-content {
        max-width: 100%;
        padding: 0;
    }
    
    .card {
        break-inside: avoid;
    }
}

/* Responsive */
@media (max-width: 1024px) {
    .systems-container {
        flex-direction: column;
        height: auto;
    }
    
    .system-list {
        width: 100%;
        max-height: 300px;
    }
}

@media (max-width: 768px) {
    .layout {
        flex-direction: column;
    }
    
    .sidebar {
        width: 100%;
        height: auto;
        position: relative;
    }
    
    .main-content {
        padding: var(--spacing-md);
    }
    
    .welcome-msg {
        font-size: 2rem;
    }
    
    .grid {
        grid-template-columns: 1fr;
    }
}