/**
 * OneLearning - Modern Design System
 * Inspired by Linear.app aesthetics
 * Target: Small-to-Medium Businesses (KKV/SMB)
 * Tone: Modern, approachable, professional - NOT corporate
 */

/* ============================================
   DESIGN TOKENS
   ============================================ */

:root {
  /* === PRIMARY BRAND COLORS === */
  --brand-primary: #5E6AD2;        /* Linear purple-blue */
  --brand-secondary: #6E56CF;      /* Vibrant purple */
  --brand-accent: #26F4D0;         /* Cyan accent */
  
  /* === GRADIENT BACKGROUNDS === */
  --gradient-hero: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  --gradient-card: linear-gradient(135deg, rgba(94, 106, 210, 0.1) 0%, rgba(110, 86, 207, 0.05) 100%);
  --gradient-cta: linear-gradient(135deg, #667eea 0%, #5E6AD2 100%);
  --gradient-text: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  
  /* === NEUTRAL PALETTE - Soft, not harsh === */
  --gray-50: #FAFAFA;
  --gray-100: #F5F5F5;
  --gray-200: #E5E5E5;
  --gray-300: #D4D4D4;
  --gray-400: #A3A3A3;
  --gray-500: #737373;
  --gray-600: #525252;
  --gray-700: #404040;
  --gray-800: #262626;
  --gray-900: #171717;
  
  /* === BACKGROUNDS === */
  --bg-primary: #FFFFFF;
  --bg-secondary: #FAFAFA;
  --bg-dark: #0A0A0A;
  --bg-dark-secondary: #171717;
  
  /* === TEXT COLORS === */
  --text-primary: #171717;
  --text-secondary: #525252;
  --text-muted: #A3A3A3;
  --text-on-dark: #FAFAFA;
  
  /* === GLASSMORPHISM - Linear style === */
  --glass-bg: rgba(255, 255, 255, 0.7);
  --glass-border: rgba(255, 255, 255, 0.3);
  --glass-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.08);
  --glass-blur: blur(12px);
  
  /* Dark theme glass (for modal) */
  --glass-dark-bg: rgba(23, 23, 23, 0.7);
  --glass-dark-border: rgba(255, 255, 255, 0.1);
  --glass-dark-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.4);
  
  /* === SHADOWS - Soft, not harsh === */
  --shadow-xs: 0 1px 2px 0 rgba(0, 0, 0, 0.03);
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
  --shadow-2xl: 0 25px 50px -12px rgba(0, 0, 0, 0.15);
  --shadow-glow: 0 0 20px rgba(94, 106, 210, 0.3);
  --shadow-glow-strong: 0 0 40px rgba(94, 106, 210, 0.5);
  
  /* === SPACING SCALE === */
  --space-xs: 0.5rem;    /* 8px */
  --space-sm: 0.75rem;   /* 12px */
  --space-md: 1rem;      /* 16px */
  --space-lg: 1.5rem;    /* 24px */
  --space-xl: 2rem;      /* 32px */
  --space-2xl: 3rem;     /* 48px */
  --space-3xl: 4rem;     /* 64px */
  --space-4xl: 6rem;     /* 96px */
  
  /* === BORDER RADIUS - Generous, modern === */
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --radius-2xl: 32px;
  --radius-full: 9999px;
  
  /* === TRANSITIONS - Smooth like Linear === */
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-base: 250ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 350ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-spring: 600ms cubic-bezier(0.34, 1.56, 0.64, 1);
  
  /* === TYPOGRAPHY === */
  --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  
  /* Font Sizes - Generous, readable */
  --text-xs: 0.75rem;     /* 12px */
  --text-sm: 0.875rem;    /* 14px */
  --text-base: 1rem;      /* 16px */
  --text-lg: 1.125rem;    /* 18px */
  --text-xl: 1.25rem;     /* 20px */
  --text-2xl: 1.5rem;     /* 24px */
  --text-3xl: 1.875rem;   /* 30px */
  --text-4xl: 2.25rem;    /* 36px */
  --text-5xl: 3rem;       /* 48px */
  --text-6xl: 3.75rem;    /* 60px */
  --text-7xl: 4.5rem;     /* 72px */
  
  /* Line Heights */
  --leading-none: 1;
  --leading-tight: 1.25;
  --leading-snug: 1.375;
  --leading-normal: 1.5;
  --leading-relaxed: 1.75;
  --leading-loose: 2;
  
  /* Font Weights */
  --font-normal: 400;
  --font-medium: 500;
  --font-semibold: 600;
  --font-bold: 700;
}

/* ============================================
   DARK MODE
   ============================================ */

/* Auto dark mode based on system preference */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    /* Backgrounds */
    --bg-primary: #0A0A0A;
    --bg-secondary: #171717;
    
    /* Text */
    --text-primary: #FAFAFA;
    --text-secondary: #A3A3A3;
    --text-muted: #737373;
    
    /* Neutrals (inverted) */
    --gray-50: #171717;
    --gray-100: #262626;
    --gray-200: #404040;
    --gray-300: #525252;
    --gray-400: #737373;
    --gray-500: #A3A3A3;
    --gray-600: #D4D4D4;
    --gray-700: #E5E5E5;
    --gray-800: #F5F5F5;
    --gray-900: #FAFAFA;
    
    /* Glass */
    --glass-bg: rgba(23, 23, 23, 0.8);
    --glass-border: rgba(255, 255, 255, 0.1);
    --glass-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.4);
    
    /* Gradients adjusted for dark */
    --gradient-card: linear-gradient(135deg, rgba(94, 106, 210, 0.15) 0%, rgba(110, 86, 207, 0.08) 100%);
    
    /* Brand colors stay vibrant but slightly adjusted */
    --brand-primary: #7B8AE6;
    --brand-secondary: #8B7AE6;
  }
}

/* Manual dark mode override */
:root[data-theme="dark"] {
  /* Backgrounds */
  --bg-primary: #0A0A0A;
  --bg-secondary: #171717;
  
  /* Text */
  --text-primary: #FAFAFA;
  --text-secondary: #A3A3A3;
  --text-muted: #737373;
  
  /* Neutrals (inverted) */
  --gray-50: #171717;
  --gray-100: #262626;
  --gray-200: #404040;
  --gray-300: #525252;
  --gray-400: #737373;
  --gray-500: #A3A3A3;
  --gray-600: #D4D4D4;
  --gray-700: #E5E5E5;
  --gray-800: #F5F5F5;
  --gray-900: #FAFAFA;
  
  /* Glass */
  --glass-bg: rgba(23, 23, 23, 0.8);
  --glass-border: rgba(255, 255, 255, 0.1);
  --glass-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.4);
  
  /* Gradients adjusted for dark */
  --gradient-card: linear-gradient(135deg, rgba(94, 106, 210, 0.15) 0%, rgba(110, 86, 207, 0.08) 100%);
  
  /* Brand colors stay vibrant but slightly adjusted */
  --brand-primary: #7B8AE6;
  --brand-secondary: #8B7AE6;
}

/* ============================================
   GOOGLE FONTS - Inter
   ============================================ */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700&display=swap');

/* ============================================
   BASE STYLES
   ============================================ */

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

html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-family);
  font-size: var(--text-base);
  line-height: var(--leading-normal);
  color: var(--text-primary);
  background: var(--bg-primary);
  font-weight: var(--font-normal);
}

h1, h2, h3, h4, h5, h6 {
  font-weight: var(--font-semibold);
  line-height: var(--leading-tight);
  color: var(--text-primary);
}

h1 { font-size: var(--text-6xl); }
h2 { font-size: var(--text-5xl); }
h3 { font-size: var(--text-4xl); }
h4 { font-size: var(--text-3xl); }
h5 { font-size: var(--text-2xl); }
h6 { font-size: var(--text-xl); }

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

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

a:hover {
  color: var(--brand-secondary);
}

/* ============================================
   COMPONENT CLASSES
   ============================================ */

/* === CARDS === */
.card {
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  box-shadow: var(--shadow-lg);
  backdrop-filter: var(--glass-blur);
  transition: transform var(--transition-base), box-shadow var(--transition-base);
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-xl), var(--shadow-glow);
}

.card-compact {
  padding: var(--space-lg);
}

.card-glass-dark {
  background: var(--glass-dark-bg);
  border-color: var(--glass-dark-border);
  box-shadow: var(--glass-dark-shadow);
  color: var(--text-on-dark);
}

/* === BUTTONS === */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  padding: var(--space-md) var(--space-xl);
  border-radius: var(--radius-full);
  font-weight: var(--font-semibold);
  font-size: var(--text-base);
  transition: all var(--transition-base);
  cursor: pointer;
  border: none;
  text-decoration: none;
  white-space: nowrap;
}

.btn-primary {
  background: var(--gradient-cta);
  color: white;
  box-shadow: var(--shadow-md), 0 0 0 rgba(94, 106, 210, 0.5);
  border: 2px solid transparent;
}

.btn-primary:hover {
  background: white;
  color: var(--brand-primary);
  border-color: var(--brand-primary);
  box-shadow: var(--shadow-lg);
  transform: translateY(-2px);
}

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

.btn-secondary {
  background: transparent;
  color: var(--brand-primary);
  border: 2px solid var(--brand-primary);
}

.btn-secondary:hover {
  background: var(--brand-primary);
  color: white;
  transform: translateY(-2px);
}

.btn-ghost {
  background: transparent;
  color: var(--text-primary);
  padding: var(--space-sm) var(--space-lg);
}

.btn-ghost:hover {
  background: var(--gray-100);
}

.btn-large {
  padding: var(--space-lg) var(--space-2xl);
  font-size: var(--text-lg);
}

.btn-small {
  padding: var(--space-sm) var(--space-lg);
  font-size: var(--text-sm);
}

/* === TEXT UTILITIES === */
.gradient-text {
  background: var(--gradient-text);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.text-primary {
  color: var(--text-primary);
}

.text-secondary {
  color: var(--text-secondary);
}

.text-muted {
  color: var(--text-muted);
}

.text-center {
  text-align: center;
}

.font-semibold {
  font-weight: var(--font-semibold);
}

.font-bold {
  font-weight: var(--font-bold);
}

/* === LINKS === */
.link-underline {
  position: relative;
  text-decoration: none;
  color: var(--text-primary);
}

.link-underline::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--gradient-cta);
  transition: width var(--transition-base);
}

.link-underline:hover::after {
  width: 100%;
}

/* === CONTAINERS === */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

.container-wide {
  max-width: 1400px;
}

.container-narrow {
  max-width: 800px;
}

/* === SECTIONS === */
.section {
  padding: var(--space-4xl) 0;
}

.section-compact {
  padding: var(--space-3xl) 0;
}

/* === GRID LAYOUTS === */
.grid {
  display: grid;
  gap: var(--space-xl);
}

.grid-2 {
  grid-template-columns: repeat(2, 1fr);
}

.grid-3 {
  grid-template-columns: repeat(3, 1fr);
}

.grid-4 {
  grid-template-columns: repeat(4, 1fr);
}

@media (max-width: 1024px) {
  .grid-3, .grid-4 {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 640px) {
  .grid-2, .grid-3, .grid-4 {
    grid-template-columns: 1fr;
  }
}

/* ============================================
   ANIMATION UTILITIES
   ============================================ */

/* Fade in on scroll */
.fade-in {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity var(--transition-slow), transform var(--transition-slow);
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* Scale in on scroll */
.scale-in {
  opacity: 0;
  transform: scale(0.95);
  transition: opacity var(--transition-slow), transform var(--transition-slow);
}

.scale-in.visible {
  opacity: 1;
  transform: scale(1);
}

/* Slide in from left */
.slide-in-left {
  opacity: 0;
  transform: translateX(-30px);
  transition: opacity var(--transition-slow), transform var(--transition-slow);
}

.slide-in-left.visible {
  opacity: 1;
  transform: translateX(0);
}

/* Slide in from right */
.slide-in-right {
  opacity: 0;
  transform: translateX(30px);
  transition: opacity var(--transition-slow), transform var(--transition-slow);
}

.slide-in-right.visible {
  opacity: 1;
  transform: translateX(0);
}

/* Pulse animation */
@keyframes pulse {
  0%, 100% {
    opacity: 1;
  }
  50% {
    opacity: 0.5;
  }
}

.pulse {
  animation: pulse 2s cubic-bezier(0.4, 0, 0.6, 1) infinite;
}

/* Glow animation */
@keyframes glow {
  0%, 100% {
    box-shadow: 0 0 20px rgba(94, 106, 210, 0.3);
  }
  50% {
    box-shadow: 0 0 40px rgba(94, 106, 210, 0.6);
  }
}

.glow {
  animation: glow 2s ease-in-out infinite;
}

/* ============================================
   UTILITY CLASSES
   ============================================ */

/* Spacing */
.mt-1 { margin-top: var(--space-xs); }
.mt-2 { margin-top: var(--space-sm); }
.mt-3 { margin-top: var(--space-md); }
.mt-4 { margin-top: var(--space-lg); }
.mt-5 { margin-top: var(--space-xl); }
.mt-6 { margin-top: var(--space-2xl); }

.mb-1 { margin-bottom: var(--space-xs); }
.mb-2 { margin-bottom: var(--space-sm); }
.mb-3 { margin-bottom: var(--space-md); }
.mb-4 { margin-bottom: var(--space-lg); }
.mb-5 { margin-bottom: var(--space-xl); }
.mb-6 { margin-bottom: var(--space-2xl); }

.p-1 { padding: var(--space-xs); }
.p-2 { padding: var(--space-sm); }
.p-3 { padding: var(--space-md); }
.p-4 { padding: var(--space-lg); }
.p-5 { padding: var(--space-xl); }
.p-6 { padding: var(--space-2xl); }

/* Display */
.flex { display: flex; }
.inline-flex { display: inline-flex; }
.grid { display: grid; }
.hidden { display: none; }

/* Flexbox utilities */
.items-center { align-items: center; }
.items-start { align-items: flex-start; }
.items-end { align-items: flex-end; }
.justify-center { justify-content: center; }
.justify-between { justify-content: space-between; }
.justify-end { justify-content: flex-end; }
.gap-1 { gap: var(--space-xs); }
.gap-2 { gap: var(--space-sm); }
.gap-3 { gap: var(--space-md); }
.gap-4 { gap: var(--space-lg); }

/* Responsive utilities */
@media (max-width: 1024px) {
  .lg\:hidden { display: none; }
}

@media (max-width: 640px) {
  .sm\:hidden { display: none; }
  .sm\:text-center { text-align: center; }
}