/**
 * KaigoHub Design System Version 2.0
 * Theme: Japanese EdTech + Premium SaaS
 * Color Tokens:
 *  - Primary: #5145CD
 *  - Deep Navy: #172554
 *  - Background: #F7F8FC
 *  - Surface: #FFFFFF
 *  - Success: #0F766E
 *  - Warning: #F59E0B
 *  - Text Primary: #172033
 *  - Text Secondary: #64748B
 *  - Border: #E5E7EB
 */

:root {
  /* Brand & Core Colors */
  --color-primary: #5145CD;
  --color-primary-hover: #4338CA;
  --color-primary-active: #3730A3;
  --color-primary-light: #EEF2FF;
  --color-primary-subtle: #F5F7FF;

  --color-navy: #172554;
  --color-navy-dark: #0F172A;
  --color-navy-light: #1E293B;

  --color-bg: #F7F8FC;
  --color-surface: #FFFFFF;
  --color-surface-subtle: #F8FAFC;

  --color-success: #0F766E;
  --color-success-hover: #115E59;
  --color-success-light: #F0FDFA;
  --color-success-border: #99F6E4;

  --color-warning: #F59E0B;
  --color-warning-hover: #D97706;
  --color-warning-light: #FFFBEB;
  --color-warning-border: #FDE68A;

  --color-danger: #E11D48;
  --color-danger-light: #FFF1F2;
  --color-danger-border: #FECDD3;

  --color-text-primary: #172033;
  --color-text-secondary: #64748B;
  --color-text-tertiary: #94A3B8;

  --color-border: #E5E7EB;
  --color-border-subtle: #F1F5F9;
  --color-border-strong: #CBD5E1;

  /* Typography */
  --font-sans: 'Be Vietnam Pro', 'Inter', 'Noto Sans JP', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-jp: 'Noto Sans JP', 'Hiragino Kaku Gothic ProN', 'Meiryo', sans-serif;

  /* Elevation & Shadows */
  --shadow-xs: 0 1px 2px 0 rgba(23, 37, 84, 0.04);
  --shadow-sm: 0 1px 3px 0 rgba(23, 37, 84, 0.06), 0 1px 2px -1px rgba(23, 37, 84, 0.04);
  --shadow-md: 0 4px 6px -1px rgba(23, 37, 84, 0.06), 0 2px 4px -2px rgba(23, 37, 84, 0.04);
  --shadow-lg: 0 10px 15px -3px rgba(23, 37, 84, 0.08), 0 4px 6px -4px rgba(23, 37, 84, 0.04);
  --shadow-xl: 0 20px 25px -5px rgba(23, 37, 84, 0.1), 0 8px 10px -6px rgba(23, 37, 84, 0.04);
  --shadow-card: 0 1px 3px rgba(23, 37, 84, 0.05), 0 20px 25px -20px rgba(23, 37, 84, 0.05);

  /* Radius */
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 20px;
  --radius-full: 9999px;

  /* Transitions */
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-normal: 250ms cubic-bezier(0.16, 1, 0.3, 1);
}

/* ==================== GLOBAL BASE RESET & TYPOGRAPHY ==================== */
html {
  font-family: var(--font-sans);
  background-color: var(--color-bg);
  color: var(--color-text-primary);
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  background-color: var(--color-bg);
  color: var(--color-text-primary);
  overflow-x: hidden;
}

/* Furigana Precision Styling */
ruby {
  ruby-align: center;
  ruby-position: over;
  line-height: 1.85;
}
rt {
  font-family: var(--font-jp);
  font-size: 0.62em;
  font-weight: 500;
  color: #5145CD;
  user-select: none;
  line-height: 1.1;
  padding-bottom: 2px;
}

/* Heading Hierarchy */
h1, h2, h3, h4, h5, h6 {
  color: var(--color-navy);
  font-weight: 700;
  letter-spacing: -0.02em;
}

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

/* Cards */
.kaigo-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition-normal), box-shadow var(--transition-normal), border-color var(--transition-normal);
}
.kaigo-card:hover {
  border-color: #CBD5E1;
  box-shadow: var(--shadow-md);
}
.kaigo-card-interactive {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition-normal), box-shadow var(--transition-normal), border-color var(--transition-normal);
  cursor: pointer;
}
.kaigo-card-interactive:hover {
  transform: translateY(-2px);
  border-color: var(--color-primary);
  box-shadow: var(--shadow-md);
}
.kaigo-card-interactive:active {
  transform: translateY(0);
}

/* Buttons */
.kaigo-btn-primary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  background-color: var(--color-primary);
  color: #FFFFFF;
  font-weight: 600;
  font-size: 0.875rem;
  padding: 0.625rem 1.25rem;
  border-radius: var(--radius-md);
  border: 1px solid transparent;
  box-shadow: 0 1px 2px 0 rgba(81, 69, 205, 0.2);
  transition: all var(--transition-fast);
  cursor: pointer;
  user-select: none;
  text-decoration: none;
}
.kaigo-btn-primary:hover {
  background-color: var(--color-primary-hover);
  box-shadow: 0 4px 12px 0 rgba(81, 69, 205, 0.25);
  transform: translateY(-1px);
}
.kaigo-btn-primary:active {
  background-color: var(--color-primary-active);
  transform: translateY(0);
}
.kaigo-btn-primary:disabled {
  opacity: 0.6;
  cursor: not-allowed;
  transform: none;
  box-shadow: none;
}

.kaigo-btn-secondary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  background-color: var(--color-surface);
  color: var(--color-navy);
  font-weight: 600;
  font-size: 0.875rem;
  padding: 0.625rem 1.25rem;
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-xs);
  transition: all var(--transition-fast);
  cursor: pointer;
  user-select: none;
  text-decoration: none;
}
.kaigo-btn-secondary:hover {
  background-color: var(--color-surface-subtle);
  border-color: var(--color-border-strong);
  color: var(--color-navy);
  transform: translateY(-1px);
}
.kaigo-btn-secondary:active {
  transform: translateY(0);
}

.kaigo-btn-ghost {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  background-color: transparent;
  color: var(--color-text-secondary);
  font-weight: 600;
  font-size: 0.875rem;
  padding: 0.5rem 0.875rem;
  border-radius: var(--radius-md);
  border: 1px solid transparent;
  transition: all var(--transition-fast);
  cursor: pointer;
  user-select: none;
  text-decoration: none;
}
.kaigo-btn-ghost:hover {
  background-color: var(--color-primary-light);
  color: var(--color-primary);
}

/* Badges */
.kaigo-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
  font-size: 0.6875rem;
  font-weight: 700;
  padding: 0.25rem 0.625rem;
  border-radius: var(--radius-full);
  line-height: 1;
}
.kaigo-badge-primary {
  background-color: var(--color-primary-light);
  color: var(--color-primary);
  border: 1px solid #C7D2FE;
}
.kaigo-badge-navy {
  background-color: #EFF6FF;
  color: var(--color-navy);
  border: 1px solid #BFDBFE;
}
.kaigo-badge-success {
  background-color: var(--color-success-light);
  color: var(--color-success);
  border: 1px solid var(--color-success-border);
}
.kaigo-badge-warning {
  background-color: var(--color-warning-light);
  color: #B45309;
  border: 1px solid var(--color-warning-border);
}

/* Inputs */
.kaigo-input {
  width: 100%;
  padding: 0.625rem 0.875rem;
  font-size: 0.875rem;
  background-color: #FFFFFF;
  color: var(--color-text-primary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  outline: none;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}
.kaigo-input:focus {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(81, 69, 205, 0.12);
}
.kaigo-input::placeholder {
  color: var(--color-text-tertiary);
}

/* Question Option States */
.kaigo-option-card {
  position: relative;
  display: flex;
  align-items: flex-start;
  gap: 0.875rem;
  padding: 1rem;
  background-color: #FFFFFF;
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition-fast);
}
.kaigo-option-card:hover {
  border-color: #CBD5E1;
  background-color: #FAFAFC;
}
.kaigo-option-card.selected {
  border-color: var(--color-primary);
  background-color: var(--color-primary-subtle);
  box-shadow: 0 0 0 1px var(--color-primary);
}
.kaigo-option-card.correct {
  border-color: var(--color-success);
  background-color: var(--color-success-light);
  box-shadow: 0 0 0 1px var(--color-success);
}
.kaigo-option-card.wrong {
  border-color: var(--color-danger);
  background-color: var(--color-danger-light);
  box-shadow: 0 0 0 1px var(--color-danger);
}

/* Skeleton Loading Animation */
.kaigo-skeleton {
  background: linear-gradient(90deg, #F1F5F9 25%, #E2E8F0 50%, #F1F5F9 75%);
  background-size: 200% 100%;
  animation: kaigoSkeleton 1.5s infinite;
  border-radius: var(--radius-sm);
}
@keyframes kaigoSkeleton {
  0% { background-position: 200% 0; }
  100% { background-position: -200% 0; }
}

/* Modals & Backdrop */
.kaigo-modal-backdrop {
  position: fixed;
  inset: 0;
  z-index: 50;
  background-color: rgba(15, 23, 42, 0.5);
  backdrop-filter: blur(4px);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1rem;
}
.kaigo-modal-box {
  background-color: #FFFFFF;
  border-radius: var(--radius-xl);
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-xl);
  max-width: 32rem;
  width: 100%;
  overflow: hidden;
  animation: kaigoModalIn 0.2s cubic-bezier(0.16, 1, 0.3, 1);
}
@keyframes kaigoModalIn {
  from {
    opacity: 0;
    transform: scale(0.96) translateY(8px);
  }
  to {
    opacity: 1;
    transform: scale(1) translateY(0);
  }
}

/* Micro Toast Notification */
.kaigo-toast {
  position: fixed;
  bottom: 1.5rem;
  right: 1.5rem;
  z-index: 60;
  max-width: 24rem;
  background: #FFFFFF;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  padding: 0.875rem 1.125rem;
  display: flex;
  align-items: center;
  gap: 0.75rem;
  animation: kaigoToastIn 0.3s cubic-bezier(0.16, 1, 0.3, 1);
}
@keyframes kaigoToastIn {
  from {
    opacity: 0;
    transform: translateY(16px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}