/* CSS Variables for Color Palette */
:root {
  --color-primary: #355C7D;
  --color-secondary: #6C5B7B;
  --color-accent-1: #C06C84;
  --color-accent-2: #F67280;
  --color-accent-3: #F8B195;
  --color-white: #ffffff;
  --color-light: #f8f9fa;
  --color-dark: #212529;
  --color-gray: #6c757d;
  --color-success: #28a745;
  --color-warning: #ffc107;
  --color-danger: #dc3545;
  --color-info: #17a2b8;
  
  /* Dark mode colors */
  --bg-primary: #ffffff;
  --bg-secondary: #f8f9fa;
  --text-primary: #212529;
  --text-secondary: #6c757d;
  --border-color: #dee2e6;
  
  /* Shadows */
  --shadow-sm: 0 0.125rem 0.25rem rgba(0, 0, 0, 0.075);
  --shadow: 0 0.5rem 1rem rgba(0, 0, 0, 0.15);
  --shadow-lg: 0 1rem 3rem rgba(0, 0, 0, 0.175);
  
  /* Transitions */
  --transition: all 0.3s ease;
  --transition-fast: all 0.15s ease;
}

/* Dark Mode Variables */
[data-theme="dark"] {
  --bg-primary: #1a1a1a;
  --bg-secondary: #2d2d2d;
  --text-primary: #ffffff;
  --text-secondary: #b0b0b0;
  --border-color: #404040;
}

/* Global Styles */
* {
  box-sizing: border-box;
}

body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  line-height: 1.6;
  color: var(--text-primary);
  background-color: var(--bg-primary);
  transition: var(--transition);
  padding-top: 76px;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  font-weight: 600;
  line-height: 1.2;
  margin-bottom: 1rem;
}

.text-gradient {
  background: linear-gradient(135deg, var(--color-accent-2), var(--color-accent-1));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* Navigation */
.navbar {
  background: linear-gradient(135deg, var(--color-primary), var(--color-secondary)) !important;
  backdrop-filter: blur(10px);
  box-shadow: var(--shadow);
}

.navbar-brand {
  font-size: 1.5rem;
}

.navbar-nav .nav-link {
  font-weight: 500;
  transition: var(--transition-fast);
}

.navbar-nav .nav-link:hover {
  color: var(--color-accent-3) !important;
}

/* Hero Section */
.hero-section {
  background: linear-gradient(135deg, var(--bg-primary) 0%, var(--bg-secondary) 100%);
  position: relative;
  overflow: hidden;
}

.hero-section::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1000 1000"><defs><pattern id="grid" width="50" height="50" patternUnits="userSpaceOnUse"><path d="M 50 0 L 0 0 0 50" fill="none" stroke="%23f0f0f0" stroke-width="1" opacity="0.3"/></pattern></defs><rect width="100%" height="100%" fill="url(%23grid)"/></svg>');
  opacity: 0.1;
  z-index: 0;
}

.hero-section .container {
  position: relative;
  z-index: 1;
}

.hero-image {
  position: relative;
  height: 400px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.floating-card {
  background: var(--color-white);
  padding: 2rem;
  border-radius: 20px;
  box-shadow: var(--shadow-lg);
  text-align: center;
  animation: float 6s ease-in-out infinite;
  border: 3px solid var(--color-accent-3);
}

@keyframes float {
  0%, 100% { transform: translateY(0px); }
  50% { transform: translateY(-20px); }
}

/* Features Section */
.features-section {
  background: var(--bg-secondary);
}

.feature-card {
  background: var(--bg-primary);
  padding: 2rem;
  border-radius: 15px;
  box-shadow: var(--shadow);
  transition: var(--transition);
  border: 2px solid transparent;
  height: 100%;
}

.feature-card:hover {
  transform: translateY(-10px);
  box-shadow: var(--shadow-lg);
  border-color: var(--color-accent-3);
}

.feature-icon {
  width: 80px;
  height: 80px;
  background: linear-gradient(135deg, var(--color-accent-2), var(--color-accent-1));
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 1.5rem;
  color: white;
  font-size: 2rem;
}

/* Calculator Section */
.calculator-section {
  background: var(--bg-primary);
}

.calculator-card {
  background: var(--bg-primary);
  padding: 3rem;
  border-radius: 20px;
  box-shadow: var(--shadow-lg);
  border: 2px solid var(--color-accent-3);
}

.form-control, .form-select {
  border: 2px solid var(--border-color);
  border-radius: 10px;
  padding: 0.75rem 1rem;
  font-size: 1rem;
  transition: var(--transition-fast);
  background-color: var(--bg-primary);
  color: var(--text-primary);
}

.form-control:focus, .form-select:focus {
  border-color: var(--color-accent-2);
  box-shadow: 0 0 0 0.2rem rgba(246, 114, 128, 0.25);
  background-color: var(--bg-primary);
  color: var(--text-primary);
}

.form-control-lg {
  padding: 1rem 1.25rem;
  font-size: 1.1rem;
}

.btn {
  border-radius: 10px;
  font-weight: 500;
  transition: var(--transition);
  border: 2px solid transparent;
}

.btn-primary {
  background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
  border-color: var(--color-primary);
}

.btn-primary:hover {
  background: linear-gradient(135deg, var(--color-secondary), var(--color-accent-1));
  transform: translateY(-2px);
  box-shadow: var(--shadow);
}

.btn-outline-primary {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

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

.btn-check:checked + .btn-outline-primary {
  background: linear-gradient(135deg, var(--color-accent-2), var(--color-accent-1));
  border-color: var(--color-accent-2);
  color: white;
}

/* Results Section */
.results-section {
  background: var(--bg-secondary);
}

.results-card {
  background: var(--bg-primary);
  padding: 3rem;
  border-radius: 20px;
  box-shadow: var(--shadow-lg);
  border: 2px solid var(--color-accent-3);
}

.time-card {
  background: linear-gradient(135deg, var(--color-accent-2), var(--color-accent-1));
  color: white;
  padding: 2rem;
  border-radius: 15px;
  text-align: center;
  box-shadow: var(--shadow);
  transition: var(--transition);
}

.time-card:hover {
  transform: scale(1.05);
}

.time-number {
  font-size: 3rem;
  font-weight: bold;
  line-height: 1;
}

.time-label {
  font-size: 1.1rem;
  opacity: 0.9;
  margin-top: 0.5rem;
}

.chart-container {
  position: relative;
  height: 300px;
  background: var(--bg-secondary);
  border-radius: 15px;
  padding: 1rem;
}

.learning-tips {
  background: var(--bg-secondary);
  padding: 2rem;
  border-radius: 15px;
}

.tip-item {
  background: var(--bg-primary);
  padding: 1rem;
  border-radius: 10px;
  margin-bottom: 1rem;
  border-left: 4px solid var(--color-accent-2);
  box-shadow: var(--shadow-sm);
}

/* Modal Styles */
.modal-content {
  border-radius: 15px;
  border: none;
  box-shadow: var(--shadow-lg);
  background-color: var(--bg-primary);
}

.modal-header {
  border-bottom: 2px solid var(--border-color);
  background: linear-gradient(135deg, var(--color-accent-3), var(--color-accent-2));
  color: white;
  border-radius: 15px 15px 0 0;
}

.modal-header .btn-close {
  filter: invert(1);
}

.level-card, .method-card {
  background: var(--bg-secondary);
  padding: 1.5rem;
  border-radius: 10px;
  border: 2px solid var(--border-color);
  transition: var(--transition);
  height: 100%;
}

.level-card:hover, .method-card:hover {
  border-color: var(--color-accent-2);
  transform: translateY(-5px);
}

.level-card.basic {
  border-left: 4px solid var(--color-success);
}

.level-card.intermediate {
  border-left: 4px solid var(--color-warning);
}

.level-card.advanced {
  border-left: 4px solid var(--color-danger);
}

/* Offcanvas */
.offcanvas {
  background-color: var(--bg-primary);
  border-left: 3px solid var(--color-accent-3);
}

.offcanvas-header {
  background: linear-gradient(135deg, var(--color-accent-3), var(--color-accent-2));
  color: white;
}

.offcanvas-header .btn-close {
  filter: invert(1);
}

.plan-card {
  background: var(--bg-secondary);
  padding: 1.5rem;
  border-radius: 10px;
  margin-bottom: 1rem;
  border: 2px solid var(--border-color);
  transition: var(--transition);
}

.plan-card:hover {
  border-color: var(--color-accent-2);
  transform: translateX(5px);
}

/* Saved Simulations */
.simulation-card {
  background: var(--bg-secondary);
  padding: 1.5rem;
  border-radius: 10px;
  margin-bottom: 1rem;
  border: 2px solid var(--border-color);
  transition: var(--transition);
}

.simulation-card:hover {
  border-color: var(--color-accent-2);
}

/* Ad Banner */
.ad-banner {
  background: var(--bg-secondary);
  padding: 1rem;
  border-radius: 10px;
  border: 2px dashed var(--border-color);
}

/* Footer */
.footer {
  background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
  color: white;
  margin-top: auto;
}

.footer a {
  color: var(--color-accent-3);
}

.footer a:hover {
  color: white;
}

/* Dark Mode Styles */
[data-theme="dark"] {
  color-scheme: dark;
}

[data-theme="dark"] .navbar {
  background: linear-gradient(135deg, #1a1a1a, #2d2d2d) !important;
}

[data-theme="dark"] .hero-section {
  background: linear-gradient(135deg, #1a1a1a 0%, #2d2d2d 100%);
}

[data-theme="dark"] .floating-card {
  background: var(--bg-secondary);
  color: var(--text-primary);
}

/* Responsive Design */
@media (max-width: 768px) {
  .hero-section {
    padding: 2rem 0;
  }
  
  .hero-section .display-4 {
    font-size: 2rem;
  }
  
  .calculator-card, .results-card {
    padding: 2rem;
    margin: 1rem;
  }
  
  .time-number {
    font-size: 2rem;
  }
  
  .feature-card {
    margin-bottom: 2rem;
  }
  
  .chart-container {
    height: 250px;
  }
}

@media (max-width: 576px) {
  body {
    padding-top: 60px;
  }
  
  .navbar-brand {
    font-size: 1.2rem;
  }
  
  .calculator-card, .results-card {
    padding: 1.5rem;
  }
  
  .hero-image {
    height: 300px;
  }
  
  .floating-card {
    padding: 1.5rem;
  }
  
  .time-card {
    padding: 1.5rem;
  }
  
  .btn-group .btn {
    font-size: 0.9rem;
    padding: 0.5rem;
  }
}

/* Animation Classes */
.fade-in {
  animation: fadeIn 0.5s ease-in;
}

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

.slide-up {
  animation: slideUp 0.5s ease-out;
}

@keyframes slideUp {
  from { transform: translateY(100px); opacity: 0; }
  to { transform: translateY(0); opacity: 1; }
}

/* Loading States */
.btn.loading {
  pointer-events: none;
  opacity: 0.7;
}

.btn.loading::after {
  content: '';
  display: inline-block;
  width: 1rem;
  height: 1rem;
  border: 2px solid currentColor;
  border-radius: 50%;
  border-right-color: transparent;
  animation: spin 0.75s linear infinite;
  margin-left: 0.5rem;
}

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

/* Accessibility */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* Focus Styles */
.btn:focus,
.form-control:focus,
.form-select:focus {
  outline: 2px solid var(--color-accent-2);
  outline-offset: 2px;
}

/* Print Styles */
@media print {
  .navbar,
  .btn,
  .modal,
  .offcanvas,
  .ad-banner {
    display: none !important;
  }
  
  body {
    padding-top: 0;
    background: white !important;
    color: black !important;
  }
  
  .calculator-card,
  .results-card {
    box-shadow: none;
    border: 1px solid #ccc;
  }
}

/* Custom Scrollbar */
::-webkit-scrollbar {
  width: 8px;
}

::-webkit-scrollbar-track {
  background: var(--bg-secondary);
}

::-webkit-scrollbar-thumb {
  background: var(--color-accent-2);
  border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
  background: var(--color-accent-1);
}

/* Utilities */
.text-primary-custom {
  color: var(--color-primary) !important;
}

.bg-primary-custom {
  background-color: var(--color-primary) !important;
}

.border-primary-custom {
  border-color: var(--color-primary) !important;
}

.gradient-bg {
  background: linear-gradient(135deg, var(--color-accent-2), var(--color-accent-1));
}

.glass-effect {
  background: rgba(255, 255, 255, 0.1);
  backdrop-filter: blur(10px);
  border: 1px solid rgba(255, 255, 255, 0.2);
}

/* High Contrast Mode */
@media (prefers-contrast: high) {
  :root {
    --shadow: 0 0 0 2px currentColor;
    --shadow-sm: 0 0 0 1px currentColor;
    --shadow-lg: 0 0 0 3px currentColor;
  }
  
  .btn {
    border-width: 3px;
  }
  
  .form-control,
  .form-select {
    border-width: 3px;
  }
}

/* Reduced Motion */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
  
  .floating-card {
    animation: none;
  }
}