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

:root {
  --primary: #6366f1;
  --primary-dark: #4f46e5;
  --primary-light: #818cf8;
  --success: #10b981;
  --success-light: #34d399;
  --warning: #f59e0b;
  --danger: #ef4444;
  --danger-light: #f87171;
  
  --bg-primary: #0f172a;
  --bg-secondary: #1e293b;
  --bg-tertiary: #334155;
  --bg-card: rgba(30, 41, 59, 0.7);
  
  --text-primary: #f1f5f9;
  --text-secondary: #cbd5e1;
  --text-muted: #94a3b8;
  
  --glass-bg: rgba(255, 255, 255, 0.05);
  --glass-border: rgba(255, 255, 255, 0.1);
  
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.1);
  --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.2);
  --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.3);
  --shadow-glow: 0 0 20px rgba(99, 102, 241, 0.4);
  
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  background: linear-gradient(135deg, var(--bg-primary) 0%, #1a1f3a 50%, var(--bg-primary) 100%);
  color: var(--text-primary);
  min-height: 100vh;
  line-height: 1.6;
  overflow-x: hidden;
}

/* Animated background */
body::before {
  content: '';
  position: fixed;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: radial-gradient(circle, rgba(99, 102, 241, 0.1) 0%, transparent 50%);
  animation: rotate 20s linear infinite;
  z-index: -1;
  pointer-events: none;
}

@keyframes rotate {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 2rem;
}

/* Header */
header {
  text-align: center;
  padding: 3rem 0 2rem;
  position: relative;
}

h1 {
  font-size: 3rem;
  font-weight: 800;
  background: linear-gradient(135deg, var(--primary-light) 0%, var(--primary) 50%, #8b5cf6 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 0.5rem;
  letter-spacing: -0.02em;
  animation: fadeInDown 0.8s ease-out;
}

@keyframes fadeInDown {
  from {
    opacity: 0;
    transform: translateY(-20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.subtitle {
  color: var(--text-secondary);
  font-size: 1.1rem;
  font-weight: 400;
}

/* Glass Cards */
.card {
  background: var(--glass-bg);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-lg);
  padding: 2rem;
  margin-bottom: 2rem;
  box-shadow: var(--shadow-md);
  transition: var(--transition);
  animation: fadeInUp 0.6s ease-out;
}

@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: rgba(255, 255, 255, 0.15);
}

.card-header {
  margin-bottom: 1.5rem;
}

.card-title {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
}

.card-description {
  color: var(--text-muted);
  font-size: 0.95rem;
}

/* Buttons */
.btn {
  padding: 0.875rem 2rem;
  border: none;
  border-radius: var(--radius-md);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  text-decoration: none;
  font-family: inherit;
  position: relative;
  overflow: hidden;
}

.btn::before {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  width: 0;
  height: 0;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.1);
  transform: translate(-50%, -50%);
  transition: width 0.6s, height 0.6s;
}

.btn:hover::before {
  width: 300px;
  height: 300px;
}

.btn-primary {
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
  color: white;
  box-shadow: 0 4px 12px rgba(99, 102, 241, 0.3);
}

.btn-primary:hover {
  box-shadow: var(--shadow-glow);
  transform: translateY(-2px);
}

.btn-success {
  background: linear-gradient(135deg, var(--success) 0%, #059669 100%);
  color: white;
}

.btn-success:hover {
  box-shadow: 0 4px 12px rgba(16, 185, 129, 0.4);
  transform: translateY(-2px);
}

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

.btn-outline:hover {
  background: var(--primary);
  color: white;
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

/* Form Elements */
input[type="date"],
input[type="text"],
input[type="number"],
select {
  width: 100%;
  padding: 0.875rem 1rem;
  border: 2px solid var(--glass-border);
  border-radius: var(--radius-md);
  background: var(--glass-bg);
  color: var(--text-primary);
  font-size: 1rem;
  font-family: inherit;
  transition: var(--transition);
}

input:focus,
select:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

/* Progress Bar */
.progress-container {
  margin: 1.5rem 0;
}

.progress-label {
  display: flex;
  justify-content: space-between;
  margin-bottom: 0.5rem;
  color: var(--text-secondary);
  font-size: 0.9rem;
  font-weight: 500;
}

.progress-bar {
  width: 100%;
  height: 12px;
  background: var(--bg-tertiary);
  border-radius: 999px;
  overflow: hidden;
  box-shadow: inset 0 2px 4px rgba(0, 0, 0, 0.2);
}

.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--primary) 0%, var(--primary-light) 100%);
  border-radius: 999px;
  transition: width 0.5s ease;
  position: relative;
  overflow: hidden;
}

.progress-fill::after {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  bottom: 0;
  right: 0;
  background: linear-gradient(
    90deg,
    rgba(255, 255, 255, 0) 0%,
    rgba(255, 255, 255, 0.3) 50%,
    rgba(255, 255, 255, 0) 100%
  );
  animation: shimmer 2s infinite;
}

@keyframes shimmer {
  0% { transform: translateX(-100%); }
  100% { transform: translateX(100%); }
}

/* Stats Grid */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1.5rem;
  margin: 2rem 0;
}

.stat-card {
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  text-align: center;
  transition: var(--transition);
}

.stat-card:hover {
  transform: translateY(-4px);
  border-color: var(--primary);
  box-shadow: var(--shadow-md);
}

.stat-value {
  font-size: 2.5rem;
  font-weight: 800;
  background: linear-gradient(135deg, var(--primary-light) 0%, var(--primary) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 0.5rem;
}

.stat-label {
  color: var(--text-secondary);
  font-size: 0.95rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* Question Card */
.question-card {
  background: var(--glass-bg);
  border: 2px solid var(--glass-border);
  border-radius: var(--radius-lg);
  padding: 2.5rem;
  margin: 2rem 0;
  box-shadow: var(--shadow-lg);
}

.question-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1.5rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--glass-border);
}

.question-code {
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--primary-light);
  background: rgba(99, 102, 241, 0.15);
  padding: 0.5rem 1rem;
  border-radius: var(--radius-sm);
}

.question-category {
  font-size: 0.85rem;
  color: var(--text-muted);
  font-weight: 500;
}

.question-text {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 2rem;
  line-height: 1.6;
}

/* Answer Options */
.answer-options {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.answer-option {
  background: var(--glass-bg);
  border: 2px solid var(--glass-border);
  border-radius: var(--radius-md);
  padding: 1.25rem 1.5rem;
  cursor: pointer;
  transition: var(--transition);
  display: flex;
  align-items: center;
  gap: 1rem;
}

.answer-option:hover {
  border-color: var(--primary);
  background: rgba(99, 102, 241, 0.1);
  transform: translateX(4px);
}

.answer-option.selected {
  border-color: var(--primary);
  background: rgba(99, 102, 241, 0.15);
}

.answer-option.correct {
  border-color: var(--success);
  background: rgba(16, 185, 129, 0.15);
}

.answer-option.incorrect {
  border-color: var(--danger);
  background: rgba(239, 68, 68, 0.15);
}

.answer-option.disabled {
  cursor: not-allowed;
  opacity: 0.7;
}

.answer-letter {
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--primary-light);
  min-width: 2rem;
}

.answer-text {
  flex: 1;
  font-size: 1rem;
  color: var(--text-primary);
}

/* Feedback */
.feedback {
  margin-top: 1.5rem;
  padding: 1.5rem;
  border-radius: var(--radius-md);
  animation: slideIn 0.3s ease-out;
}

@keyframes slideIn {
  from {
    opacity: 0;
    transform: translateY(-10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.feedback-correct {
  background: rgba(16, 185, 129, 0.15);
  border: 2px solid var(--success);
}

.feedback-incorrect {
  background: rgba(239, 68, 68, 0.15);
  border: 2px solid var(--danger);
}

.feedback-title {
  font-weight: 700;
  font-size: 1.1rem;
  margin-bottom: 0.75rem;
}

.feedback-correct .feedback-title {
  color: var(--success-light);
}

.feedback-incorrect .feedback-title {
  color: var(--danger-light);
}

.feedback-text {
  color: var(--text-secondary);
  line-height: 1.6;
}

/* AI Explanation Section */
.ai-explanation {
  margin-top: 1rem;
  padding: 1.5rem;
  background: rgba(139, 92, 246, 0.1);
  border: 1px solid rgba(139, 92, 246, 0.3);
  border-radius: var(--radius-md);
}

.ai-explanation-header {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 1rem;
  color: #a78bfa;
  font-weight: 600;
}

.ai-explanation-content {
  color: var(--text-secondary);
  line-height: 1.8;
}

.loading-spinner {
  display: inline-block;
  width: 16px;
  height: 16px;
  border: 2px solid rgba(167, 139, 250, 0.3);
  border-top-color: #a78bfa;
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

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

/* Topic Grid */
.topic-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.5rem;
  margin: 2rem 0;
}

.topic-card {
  background: var(--glass-bg);
  border: 2px solid var(--glass-border);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  transition: var(--transition);
  cursor: pointer;
}

.topic-card:hover {
  border-color: var(--primary);
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
}

.topic-card.weak {
  border-color: var(--warning);
}

.topic-card.strong {
  border-color: var(--success);
}

.topic-title {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
}

.topic-subtitle {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 1rem;
}

.topic-accuracy {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: 1rem;
}

.accuracy-value {
  font-size: 1.5rem;
  font-weight: 800;
}

.accuracy-value.high {
  color: var(--success);
}

.accuracy-value.medium {
  color: var(--warning);
}

.accuracy-value.low {
  color: var(--danger);
}

/* Navigation */
.navigation {
  display: flex;
  justify-content: center;
  gap: 1rem;
  margin: 2rem 0;
  flex-wrap: wrap;
}

/* Utilities */
.hidden {
  display: none !important;
}

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

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

.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mt-4 { margin-top: 2rem; }

.mb-1 { margin-bottom: 0.5rem; }
.mb-2 { margin-bottom: 1rem; }
.mb-3 { margin-bottom: 1.5rem; }
.mb-4 { margin-bottom: 2rem; }

/* Countdown Timer */
.countdown {
  text-align: center;
  padding: 2rem;
  background: linear-gradient(135deg, rgba(99, 102, 241, 0.2) 0%, rgba(139, 92, 246, 0.2) 100%);
  border-radius: var(--radius-lg);
  margin: 2rem 0;
  border: 2px solid var(--glass-border);
}

.countdown-value {
  font-size: 4rem;
  font-weight: 900;
  background: linear-gradient(135deg, var(--primary-light) 0%, #a78bfa 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  line-height: 1;
  margin-bottom: 0.5rem;
}

.countdown-label {
  font-size: 1.1rem;
  color: var(--text-secondary);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.1em;
}

/* Responsive Design */
@media (max-width: 768px) {
  .container {
    padding: 1rem;
  }
  
  h1 {
    font-size: 2rem;
  }
  
  .card {
    padding: 1.5rem;
  }
  
  .stats-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  
  .countdown-value {
    font-size: 3rem;
  }
  
  .question-text {
    font-size: 1.1rem;
  }
  
  .topic-grid {
    grid-template-columns: 1fr;
  }
}

/* Success Animation */
@keyframes celebrate {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.05); }
}

.celebrate {
  animation: celebrate 0.5s ease-in-out;
}

/* Badge */
.badge {
  display: inline-block;
  padding: 0.35rem 0.75rem;
  border-radius: 999px;
  font-size: 0.85rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.badge-success {
  background: rgba(16, 185, 129, 0.2);
  color: var(--success-light);
}

.badge-warning {
  background: rgba(245, 158, 11, 0.2);
  color: var(--warning);
}

.badge-danger {
  background: rgba(239, 68, 68, 0.2);
  color: var(--danger-light);
}

.badge-primary {
  background: rgba(99, 102, 241, 0.2);
  color: var(--primary-light);
}