/* ============================================
   AQA Chemistry 6-Mark Master - Styles
   Color Palette: Teal/Blue/White (Science Theme)
   ============================================ */

:root {
  /* Primary Colors */
  --color-primary: #0d9488;
  --color-primary-dark: #0f766e;
  --color-primary-light: #14b8a6;
  
  /* Secondary Colors */
  --color-secondary: #0ea5e9;
  --color-secondary-dark: #0284c7;
  
  /* Accent (CTA) */
  --color-cta: #f59e0b;
  --color-cta-dark: #d97706;
  --color-cta-light: #fbbf24;
  
  /* Neutrals */
  --color-bg: #f0fdfa;
  --color-surface: #ffffff;
  --color-text: #134e4a;
  --color-text-muted: #5f9ea0;
  --color-border: #99f6e4;
  
  /* Semantic */
  --color-success: #10b981;
  --color-error: #ef4444;
  --color-warning: #f59e0b;
  
  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(13, 148, 136, 0.08);
  --shadow-md: 0 4px 12px rgba(13, 148, 136, 0.12);
  --shadow-lg: 0 8px 24px rgba(13, 148, 136, 0.16);
  
  /* Spacing */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;
  
  /* Border Radius */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  
  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-normal: 250ms ease;
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background: linear-gradient(135deg, var(--color-bg) 0%, #ccfbf1 50%, #e0f2fe 100%);
  color: var(--color-text);
  line-height: 1.6;
  min-height: 100vh;
}

/* Container */
.container {
  max-width: 720px;
  margin: 0 auto;
  padding: var(--space-lg);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Header */
.header {
  text-align: center;
  padding: var(--space-xl) 0;
}

.header h1 {
  font-size: 2rem;
  font-weight: 700;
  color: var(--color-primary-dark);
  margin-bottom: var(--space-sm);
  letter-spacing: -0.02em;
}

.header .tagline {
  font-size: 1.1rem;
  color: var(--color-text-muted);
  font-weight: 500;
}

/* Main Content */
.main-content {
  flex: 1;
}

/* Form Styling */
.grading-form {
  background: var(--color-surface);
  padding: var(--space-xl);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-lg);
  border: 1px solid var(--color-border);
}

.input-group {
  margin-bottom: var(--space-lg);
}

.input-group label {
  display: block;
  font-weight: 600;
  margin-bottom: var(--space-sm);
  color: var(--color-primary-dark);
  font-size: 0.95rem;
}

.input-group textarea {
  width: 100%;
  padding: var(--space-md);
  border: 2px solid var(--color-border);
  border-radius: var(--radius-md);
  font-family: inherit;
  font-size: 1rem;
  resize: vertical;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
  background: #f0fdfa;
}

.input-group textarea:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(13, 148, 136, 0.15);
  background: var(--color-surface);
}

.input-group textarea::placeholder {
  color: var(--color-text-muted);
  opacity: 0.7;
}

/* Primary Button */
.btn-primary {
  width: 100%;
  padding: var(--space-md) var(--space-lg);
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
  color: white;
  border: none;
  border-radius: var(--radius-md);
  font-size: 1.1rem;
  font-weight: 600;
  cursor: pointer;
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
  position: relative;
  overflow: hidden;
}

.btn-primary:hover:not(:disabled) {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

.btn-primary:active:not(:disabled) {
  transform: translateY(0);
}

.btn-primary:disabled {
  opacity: 0.7;
  cursor: not-allowed;
}

.btn-text,
.btn-loading {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
}

/* Spinner */
.spinner {
  width: 20px;
  height: 20px;
  border: 2px solid rgba(255, 255, 255, 0.3);
  border-top-color: white;
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

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

/* Results Section */
.results-section {
  margin-top: var(--space-xl);
  animation: fadeIn 0.4s ease;
}

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

.results-section h2 {
  text-align: center;
  color: var(--color-primary-dark);
  margin-bottom: var(--space-lg);
}

/* Score Card */
.score-card {
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-secondary) 100%);
  color: white;
  padding: var(--space-xl);
  border-radius: var(--radius-xl);
  text-align: center;
  margin-bottom: var(--space-lg);
  box-shadow: var(--shadow-lg);
}

.score-display {
  font-size: 3.5rem;
  font-weight: 700;
  line-height: 1;
  margin-bottom: var(--space-sm);
}

.score-value {
  font-size: 4rem;
}

.score-total {
  opacity: 0.8;
}

.score-label {
  font-size: 1.25rem;
  font-weight: 600;
  opacity: 0.9;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* Feedback & Model Answer Cards */
.feedback-card,
.model-answer-card {
  background: var(--color-surface);
  padding: var(--space-lg);
  border-radius: var(--radius-lg);
  margin-bottom: var(--space-lg);
  box-shadow: var(--shadow-md);
  border: 1px solid var(--color-border);
}

.feedback-card h3,
.model-answer-card h3 {
  color: var(--color-primary-dark);
  margin-bottom: var(--space-md);
  font-size: 1.1rem;
}

.feedback-content,
.model-answer-content {
  color: var(--color-text);
  line-height: 1.7;
  white-space: pre-wrap;
}

.model-answer-card {
  border-left: 4px solid var(--color-success);
  background: linear-gradient(135deg, #ecfdf5 0%, var(--color-surface) 100%);
}

/* CTA Section */
.cta-section {
  margin: var(--space-xl) 0;
}

.cta-card {
  background: linear-gradient(135deg, #fef3c7 0%, #fde68a 100%);
  padding: var(--space-xl);
  border-radius: var(--radius-xl);
  text-align: center;
  border: 2px solid var(--color-cta);
  position: relative;
  overflow: hidden;
}

.cta-badge {
  position: absolute;
  top: 12px;
  right: -30px;
  background: var(--color-error);
  color: white;
  padding: var(--space-xs) var(--space-xl);
  font-size: 0.7rem;
  font-weight: 700;
  transform: rotate(45deg);
  letter-spacing: 0.05em;
}

.cta-card h3 {
  color: #92400e;
  margin-bottom: var(--space-sm);
  font-size: 1.25rem;
}

.cta-card p {
  color: #a16207;
  margin-bottom: var(--space-md);
}

.cta-card ul {
  list-style: none;
  text-align: left;
  display: inline-block;
  margin-bottom: var(--space-lg);
}

.cta-card li {
  color: #92400e;
  padding: var(--space-xs) 0;
  font-weight: 500;
}

.btn-cta {
  display: inline-block;
  background: linear-gradient(135deg, var(--color-cta) 0%, var(--color-cta-dark) 100%);
  color: white;
  padding: var(--space-md) var(--space-xl);
  border-radius: var(--radius-md);
  text-decoration: none;
  font-weight: 700;
  font-size: 1.1rem;
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
  box-shadow: var(--shadow-md);
}

.btn-cta:hover {
  transform: translateY(-2px) scale(1.02);
  box-shadow: var(--shadow-lg);
}

/* Secondary Button */
.btn-secondary {
  width: 100%;
  padding: var(--space-md);
  background: transparent;
  color: var(--color-primary);
  border: 2px solid var(--color-primary);
  border-radius: var(--radius-md);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-fast);
}

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

/* Error Message */
.error-message {
  background: #fef2f2;
  border: 1px solid #fecaca;
  color: var(--color-error);
  padding: var(--space-md);
  border-radius: var(--radius-md);
  margin-top: var(--space-lg);
  text-align: center;
}

/* Footer */
.footer {
  text-align: center;
  padding: var(--space-xl) 0 var(--space-md);
  color: var(--color-text-muted);
  font-size: 0.9rem;
}

.footer .disclaimer {
  font-size: 0.8rem;
  opacity: 0.7;
  margin-top: var(--space-xs);
}

/* Responsive Design */
@media (max-width: 640px) {
  .container {
    padding: var(--space-md);
  }

  .header h1 {
    font-size: 1.5rem;
  }

  .header .tagline {
    font-size: 0.95rem;
  }

  .grading-form {
    padding: var(--space-lg);
  }

  .score-display {
    font-size: 2.5rem;
  }

  .score-value {
    font-size: 3rem;
  }

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

  .cta-badge {
    right: -35px;
    font-size: 0.6rem;
  }
}

/* Utility: Hidden */
[hidden] {
  display: none !important;
}