/* LingLang Design System — "Cognitive Sanctuary" */
/* Shared tokens for landing page and dashboard */

:root {
  /* Surface hierarchy — no borders, only tonal shifts */
  --surface:          #0b1326;
  --surface-low:      #131b2e;
  --surface-mid:      #1a2035;
  --surface-high:     #222a3d;
  --surface-top:      #2d3449;
  --surface-well:     #060e20;

  /* Accent palette */
  --primary:          #b4c5ff;
  --primary-rgb:     180, 197, 255;
  --primary-container:#001442;
  --primary-gradient: linear-gradient(135deg, #b4c5ff 0%, #4278ff 100%);
  --secondary:        #4edea3;
  --secondary-rgb:   78, 222, 163;
  --secondary-dim:   #00a572;
  --tertiary:         #7bd0ff;
  --tertiary-rgb:    123, 208, 255;
  --tertiary-container:#001a27;
  --error:            #ffb4ab;
  --error-container:  #93000a;

  /* Text */
  --on-surface:       #dae2fd;
  --on-surface-variant:#c6c6cd;
  --on-primary:       #002a78;
  --on-surface-muted: #909097;

  /* Structural */
  --outline-variant:  #45464d;

  /* Typography */
  --font-display:     'Manrope', system-ui, -apple-system, sans-serif;
  --font-body:        'Inter', system-ui, -apple-system, sans-serif;
  --font-mono:        'JetBrains Mono', 'Fira Code', ui-monospace, monospace;

  /* Sizes */
  --radius-sm:        0.5rem;
  --radius-md:        0.75rem;
  --radius-lg:        1rem;
  --radius-xl:        1.5rem;
  --radius-2xl:       2rem;

  /* Spacing */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.25rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;
  --space-24: 6rem;

  /* Shadows — tinted, never pure black */
  --shadow-float:     0 20px 60px -15px rgba(0, 20, 66, 0.35);
  --shadow-subtle:    0 4px 20px -4px rgba(0, 20, 66, 0.2);
  --shadow-glow-primary: 0 0 20px rgba(180, 197, 255, 0.3);
  --shadow-glow-secondary: 0 0 20px rgba(78, 222, 163, 0.3);

  /* Glassmorphism */
  --glass-bg:         rgba(23, 31, 51, 0.4);
  --glass-blur:       20px;

  /* Transitions */
  --transition-fast:   150ms ease;
  --transition-base:  250ms ease;
  --transition-slow:  400ms ease;
}

/* Google Fonts import */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600&family=Manrope:wght@400;500;600;700;800&family=JetBrains+Mono:wght@400;500&display=swap');

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-body);
  background: var(--surface);
  color: var(--on-surface);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

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

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-display);
  line-height: 1.2;
}

/* Shared utility classes */
.surface-card {
  background: var(--surface-low);
  border-radius: var(--radius-md);
  padding: var(--space-6);
  transition: background var(--transition-base), transform var(--transition-base);
}
.surface-card:hover {
  background: var(--surface-high);
  transform: translateY(-2px);
}

.surface-card-elevated {
  background: var(--surface-high);
  border-radius: var(--radius-md);
  padding: var(--space-6);
}

.text-primary { color: var(--primary); }
.text-secondary { color: var(--secondary); }
.text-tertiary { color: var(--tertiary); }
.text-muted { color: var(--on-surface-muted); }
.text-error { color: var(--error); }

.font-display { font-family: var(--font-display); }
.font-mono { font-family: var(--font-mono); }

/* Button styles */
.btn-primary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-8);
  background: var(--primary-gradient);
  color: var(--on-primary);
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1rem;
  border-radius: var(--radius-sm);
  border: none;
  cursor: pointer;
  transition: all var(--transition-base);
  text-decoration: none;
  letter-spacing: 0.01em;
}
.btn-primary:hover {
  transform: translateY(-1px);
  box-shadow: var(--shadow-glow-primary);
}
.btn-primary:active {
  transform: translateY(0);
}

.btn-secondary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-8);
  background: var(--surface-high);
  color: var(--on-surface);
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1rem;
  border-radius: var(--radius-sm);
  border: none;
  cursor: pointer;
  transition: all var(--transition-base);
  text-decoration: none;
}
.btn-secondary:hover {
  background: var(--surface-top);
  color: var(--primary);
}

/* Progress bar */
.progress-track {
  width: 100%;
  height: 0.5rem;
  background: var(--surface-well);
  border-radius: var(--radius-sm);
  overflow: hidden;
}
.progress-fill {
  height: 100%;
  background: var(--secondary);
  border-radius: var(--radius-sm);
  transition: width var(--transition-slow);
  box-shadow: 0 0 8px rgba(78, 222, 163, 0.4);
}

/* Stacked progress bar for FSRS states */
.progress-stacked {
  display: flex;
  width: 100%;
  height: 0.5rem;
  border-radius: var(--radius-sm);
  overflow: hidden;
  background: var(--surface-well);
}
.progress-stacked .stack-new { background: var(--tertiary); }
.progress-stacked .stack-learning { background: var(--primary); }
.progress-stacked .stack-review { background: var(--secondary); }
.progress-stacked .stack-relearning { background: var(--error); }

/* State badges */
.badge {
  display: inline-flex;
  align-items: center;
  padding: var(--space-1) var(--space-3);
  border-radius: var(--radius-xl);
  font-size: 0.75rem;
  font-weight: 500;
  font-family: var(--font-body);
  letter-spacing: 0.02em;
}
.badge-new { background: rgba(123, 208, 255, 0.15); color: var(--tertiary); }
.badge-learning { background: rgba(180, 197, 255, 0.15); color: var(--primary); }
.badge-review { background: rgba(78, 222, 163, 0.15); color: var(--secondary); }
.badge-relearning { background: rgba(255, 180, 171, 0.15); color: var(--error); }

/* Scroll-triggered animation base */
.reveal {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}
.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

/* Loading spinner */
.loading-spinner {
  width: 2rem;
  height: 2rem;
  border: 2px solid var(--surface-high);
  border-top-color: var(--primary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
  margin: var(--space-4) auto;
}
@keyframes spin {
  to { transform: rotate(360deg); }
}

/* Section shared */
.section-inner {
  max-width: 1200px;
  margin: 0 auto;
  padding: var(--space-20) var(--space-8);
}