/*
 * CloudKlass Academy - Base CSS
 * Design System: Modern, Clean, Mobile-First
 */

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

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
  font-size: 16px;
  line-height: 1.6;
  color: var(--text);
  background: var(--bg);
  min-height: 100vh;
}

/* ===== Design Tokens ===== */
:root {
  /* Primary Colors */
  --primary: #2563eb;
  --primary-light: #3b82f6;
  --primary-dark: #1d4ed8;
  --primary-bg: rgba(37, 99, 235, 0.1);
  
  /* Accent */
  --accent: #10b981;
  --accent-light: #34d399;
  --warning: #f59e0b;
  --error: #ef4444;
  --error-bg: rgba(239, 68, 68, 0.1);
  
  /* Neutrals */
  --bg: #f8fafc;
  --bg-alt: #f1f5f9;
  --card-bg: #ffffff;
  --card-hover: #fafafa;
  --border: #e2e8f0;
  --border-focus: #3b82f6;
  
  /* Text */
  --text: #1e293b;
  --text-light: #64748b;
  --text-muted: #94a3b8;
  --text-inverse: #ffffff;
  
  /* Spacing */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;
  
  /* Radius */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-full: 9999px;
  
  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -4px rgba(0, 0, 0, 0.1);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 8px 10px -6px rgba(0, 0, 0, 0.1);
  
  /* Transitions */
  --transition-fast: 150ms ease;
  --transition: 200ms ease;
  --transition-slow: 300ms ease;
  
  /* Container */
  --container-max: 1200px;
  --container-narrow: 640px;
}

/* ===== Typography ===== */
h1, h2, h3, h4, h5, h6 {
  font-weight: 600;
  line-height: 1.3;
  color: var(--text);
}

h1 { font-size: 2rem; }
h2 { font-size: 1.5rem; }
h3 { font-size: 1.25rem; }
h4 { font-size: 1.125rem; }

@media (min-width: 768px) {
  h1 { font-size: 2.5rem; }
  h2 { font-size: 1.875rem; }
  h3 { font-size: 1.5rem; }
}

p {
  color: var(--text-light);
  margin-bottom: var(--space-md);
}

a {
  color: var(--primary);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--primary-dark);
}

/* ===== Layout ===== */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--space-md);
}

.container-narrow {
  max-width: var(--container-narrow);
}

.page {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.page-content {
  flex: 1;
  padding: var(--space-xl) 0;
}

/* Center layout for auth pages */
.page-center {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-lg);
}

/* ===== Utilities ===== */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.text-primary { color: var(--primary); }
.text-muted { color: var(--text-muted); }
.text-error { color: var(--error); }
.text-success { color: var(--accent); }

.mt-sm { margin-top: var(--space-sm); }
.mt-md { margin-top: var(--space-md); }
.mt-lg { margin-top: var(--space-lg); }
.mt-xl { margin-top: var(--space-xl); }

.mb-sm { margin-bottom: var(--space-sm); }
.mb-md { margin-bottom: var(--space-md); }
.mb-lg { margin-bottom: var(--space-lg); }
.mb-xl { margin-bottom: var(--space-xl); }

.flex { display: flex; }
.flex-col { flex-direction: column; }
.items-center { align-items: center; }
.justify-center { justify-content: center; }
.justify-between { justify-content: space-between; }
.gap-sm { gap: var(--space-sm); }
.gap-md { gap: var(--space-md); }
.gap-lg { gap: var(--space-lg); }

.hidden { display: none !important; }
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* ===== Loading States ===== */
.loading {
  opacity: 0.6;
  pointer-events: none;
}

.spinner {
  width: 20px;
  height: 20px;
  border: 2px solid var(--border);
  border-top-color: var(--primary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

.spinner-lg {
  width: 40px;
  height: 40px;
  border-width: 3px;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

/* Page loading overlay */
.page-loading {
  position: fixed;
  inset: 0;
  background: var(--bg);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 9999;
  transition: opacity var(--transition-slow);
}

.page-loading.fade-out {
  opacity: 0;
  pointer-events: none;
}

/* ===== Breakpoints reference ===== */
/*
  Mobile: < 640px (default)
  Tablet: >= 640px
  Desktop: >= 768px
  Wide: >= 1024px
*/