/* ==========================================================================
   IBM Mainframe Learning Platform - Refreshing Modern Light Theme
   Inspired by: Apple Developer Documentation & IBM Carbon Light System
   ========================================================================== */

@import url('https://fonts.googleapis.com/css2?family=IBM+Plex+Mono:wght@400;500;600&family=IBM+Plex+Sans:wght@300;400;500;600;700;800&family=Inter:wght@300;400;500;600;700;800;900&display=swap');

:root {
  /* Color Tokens - Modern Light Palette */
  --bg-dark: #f8fafc;
  --bg-surface: #ffffff;
  --bg-surface-hover: #f1f5f9;
  --bg-card: #ffffff;
  --bg-glass: rgba(255, 255, 255, 0.9);
  
  /* Primary IBM Blue Colors */
  --ibm-blue: #0f62fe;
  --ibm-blue-hover: #0043ce;
  --ibm-blue-light: #eff6ff;
  --ibm-blue-border: #bfdbfe;
  
  /* Accent Colors */
  --accent-cyan: #0284c7;
  --accent-emerald: #059669;
  --accent-amber: #d97706;
  --accent-purple: #7c3aed;
  
  /* Neutral / Text Colors */
  --text-main: #0f172a;
  --text-secondary: #334155;
  --text-muted: #64748b;
  --border-color: #e2e8f0;
  --border-color-hover: rgba(15, 98, 254, 0.3);
  
  /* Layout Dimensions */
  --sidebar-width: 300px;
  --header-height: 65px;
  --container-max-width: 100%;
  
  /* Radii & Shadows */
  --radius-sm: 10px;
  --radius-md: 16px;
  --radius-lg: 24px;
  --radius-pill: 9999px;
  
  --shadow-sm: 0 2px 10px rgba(15, 23, 42, 0.04);
  --shadow-md: 0 10px 30px rgba(15, 98, 254, 0.08);
  --shadow-glow: 0 0 20px rgba(15, 98, 254, 0.15);
  
  /* Transitions */
  --transition-fast: 0.15s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-normal: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-smooth: 0.4s cubic-bezier(0.16, 1, 0.3, 1);
}

/* Global Reset */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
  width: 100%;
  height: 100%;
}

body {
  font-family: 'Inter', 'IBM Plex Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background-color: var(--bg-dark);
  color: var(--text-main);
  line-height: 1.65;
  min-height: 100vh;
  width: 100%;
  height: 100%;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  background-image: 
    radial-gradient(circle at 10% 10%, rgba(15, 98, 254, 0.04) 0%, transparent 40%),
    radial-gradient(circle at 90% 80%, rgba(2, 132, 199, 0.04) 0%, transparent 40%);
  background-attachment: fixed;
}

/* Scrollbar Styling */
::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}

::-webkit-scrollbar-track {
  background: var(--bg-dark);
}

::-webkit-scrollbar-thumb {
  background: #cbd5e1;
  border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
  background: var(--ibm-blue);
}

/* Selection */
::selection {
  background: rgba(15, 98, 254, 0.15);
  color: var(--ibm-blue-hover);
}

/* Typography Headings */
h1, h2, h3, h4, h5, h6 {
  font-family: 'IBM Plex Sans', 'Inter', sans-serif;
  font-weight: 700;
  color: var(--text-main);
  letter-spacing: -0.02em;
}

h1 { font-size: 2.25rem; line-height: 1.3; }
h2 { font-size: 1.75rem; line-height: 1.35; }
h3 { font-size: 1.35rem; line-height: 1.4; }
h4 { font-size: 1.1rem; line-height: 1.45; }

p {
  color: var(--text-secondary);
  font-size: 1.025rem;
}

/* Code Typography */
code, pre, .font-mono {
  font-family: 'IBM Plex Mono', 'JetBrains Mono', monospace;
}

/* Utility Animations */
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

.animate-fade-in {
  animation: fadeIn 0.3s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}