/* CSS Variables for Theme Management */
:root {
  --primary-color: #E94560;
  --secondary-color: #0F3460;
  --dark-primary: #1A1A2E;
  --dark-secondary: #16213E;
  --light-color: #FFFFFF;
  --text-light: #f8f9fa;
  --text-dark: #212529;
  --border-color: #dee2e6;
  --shadow: 0 0.125rem 0.25rem rgba(0, 0, 0, 0.075);
  --shadow-lg: 0 1rem 3rem rgba(0, 0, 0, 0.175);
}

/* Dark Theme Variables */
[data-theme="dark"] {
  --light-color: #1A1A2E;
  --text-light: #f8f9fa;
  --text-dark: #f8f9fa;
  --border-color: #495057;
  --shadow: 0 0.125rem 0.25rem rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 1rem 3rem rgba(0, 0, 0, 0.4);
}

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

body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background: linear-gradient(135deg, var(--dark-secondary) 0%, var(--secondary-color) 100%);
  color: var(--text-dark);
  min-height: 100vh;
  transition: all 0.3s ease;
}

[data-theme="dark"] body {
  background: linear-gradient(135deg, var(--dark-primary) 0%, var(--dark-secondary) 100%);
  color: var(--text-light);
}

/* Header Styles */
.header-main {
  background: linear-gradient(135deg, var(--dark-primary) 0%, var(--primary-color) 100%);
  box-shadow: var(--shadow-lg);
  position: sticky;
  top: 0;
  z-index: 1020;
}

/* Card Styles */
.card {
  background-color: var(--light-color);
  border: 1px solid var(--border-color);
  border-radius: 1rem;
  box-shadow: var(--shadow);
  transition: all 0.3s ease;
  margin-bottom: 1.5rem;
}

.card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

[data-theme="dark"] .card {
  background-color: var(--dark-secondary);
  border-color: #495057;
  color: var(--text-light);
}

.calculator-card .card-header {
  background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
  color: white;
  border-radius: 1rem 1rem 0 0 !important;
  border-bottom: none;
}

/* Form Styles */
.form-control, .form-select {
  border-radius: 0.75rem;
  border: 2px solid var(--border-color);
  padding: 0.75rem 1rem;
  transition: all 0.3s ease;
  background-color: var(--light-color);
  color: var(--text-dark);
}

.form-control:focus, .form-select:focus {
  border-color: var(--primary-color);
  box-shadow: 0 0 0 0.2rem rgba(233, 69, 96, 0.25);
  background-color: var(--light-color);
}

[data-theme="dark"] .form-control,
[data-theme="dark"] .form-select {
  background-color: var(--dark-primary);
  border-color: #495057;
  color: var(--text-light);
}

[data-theme="dark"] .form-control:focus,
[data-theme="dark"] .form-select:focus {
  background-color: var(--dark-primary);
  color: var(--text-light);
}

.form-label {
  font-weight: 600;
  color: var(--text-dark);
  margin-bottom: 0.5rem;
}

[data-theme="dark"] .form-label {
  color: var(--text-light);
}

/* Button Styles */
.btn-primary {
  background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
  border: none;
  border-radius: 0.75rem;
  padding: 0.75rem 2rem;
  font-weight: 600;
  transition: all 0.3s ease;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
  background: linear-gradient(135deg, #d63851 0%, #0d2d52 100%);
}

.btn-outline-primary {
  border: 2px solid var(--primary-color);
  color: var(--primary-color);
  border-radius: 0.75rem;
  font-weight: 600;
  transition: all 0.3s ease;
}

.btn-outline-primary:hover {
  background-color: var(--primary-color);
  border-color: var(--primary-color);
  transform: translateY(-1px);
}

/* Result Styles */
.result-card {
  background: linear-gradient(135deg, var(--light-color) 0%, #f8f9fa 100%);
  border: 2px solid var(--primary-color);
}

[data-theme="dark"] .result-card {
  background: linear-gradient(135deg, var(--dark-secondary) 0%, var(--dark-primary) 100%);
}

.result-value {
  padding: 1rem;
  border-radius: 1rem;
  background: linear-gradient(135deg, rgba(233, 69, 96, 0.1) 0%, rgba(15, 52, 96, 0.1) 100%);
  margin: 1rem 0;
}

/* Training Zones Styles */
.zone-card {
  border-radius: 1rem;
  padding: 1.5rem;
  text-align: center;
  transition: all 0.3s ease;
  margin-bottom: 1rem;
  position: relative;
  overflow: hidden;
}

.zone-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--zone-color) 0%, rgba(255,255,255,0.3) 100%);
}

.zone-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-lg);
}

.zone-strength {
  --zone-color: #dc3545;
  background: linear-gradient(135deg, rgba(220, 53, 69, 0.1) 0%, rgba(220, 53, 69, 0.05) 100%);
  border: 2px solid rgba(220, 53, 69, 0.2);
}

.zone-hypertrophy {
  --zone-color: #fd7e14;
  background: linear-gradient(135deg, rgba(253, 126, 20, 0.1) 0%, rgba(253, 126, 20, 0.05) 100%);
  border: 2px solid rgba(253, 126, 20, 0.2);
}

.zone-endurance {
  --zone-color: #198754;
  background: linear-gradient(135deg, rgba(25, 135, 84, 0.1) 0%, rgba(25, 135, 84, 0.05) 100%);
  border: 2px solid rgba(25, 135, 84, 0.2);
}

.zone-title {
  font-size: 1.2rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
}

.zone-percentage {
  font-size: 2rem;
  font-weight: 800;
  margin: 0.5rem 0;
}

.zone-weight {
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--primary-color);
  margin-bottom: 0.5rem;
}

.zone-reps {
  font-size: 0.9rem;
  opacity: 0.8;
  font-style: italic;
}

/* History Styles */
.history-item {
  background: var(--light-color);
  border: 1px solid var(--border-color);
  border-radius: 0.75rem;
  padding: 1rem;
  margin-bottom: 0.75rem;
  transition: all 0.3s ease;
  position: relative;
}

.history-item:hover {
  transform: translateX(5px);
  box-shadow: var(--shadow);
  border-color: var(--primary-color);
}

[data-theme="dark"] .history-item {
  background-color: var(--dark-primary);
  border-color: #495057;
}

.history-date {
  font-size: 0.8rem;
  color: #6c757d;
  position: absolute;
  top: 0.5rem;
  right: 1rem;
}

.history-exercise {
  font-weight: 600;
  color: var(--primary-color);
  margin-bottom: 0.25rem;
}

.history-details {
  font-size: 0.9rem;
  color: var(--text-dark);
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}

[data-theme="dark"] .history-details {
  color: var(--text-light);
}

/* FAQ Styles */
.accordion-button {
  background-color: var(--light-color);
  color: var(--text-dark);
  border: none;
  border-radius: 0.75rem !important;
  font-weight: 600;
  padding: 1rem 1.25rem;
}

.accordion-button:not(.collapsed) {
  background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
  color: white;
  box-shadow: none;
}

.accordion-button:focus {
  box-shadow: 0 0 0 0.2rem rgba(233, 69, 96, 0.25);
}

[data-theme="dark"] .accordion-button {
  background-color: var(--dark-secondary);
  color: var(--text-light);
}

.accordion-body {
  background-color: var(--light-color);
  color: var(--text-dark);
  border-radius: 0 0 0.75rem 0.75rem;
  padding: 1.25rem;
}

[data-theme="dark"] .accordion-body {
  background-color: var(--dark-primary);
  color: var(--text-light);
}

/* Modal Styles */
.modal-content {
  border-radius: 1rem;
  border: none;
  background-color: var(--light-color);
  color: var(--text-dark);
}

[data-theme="dark"] .modal-content {
  background-color: var(--dark-secondary);
  color: var(--text-light);
}

.modal-header {
  background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
  color: white;
  border-radius: 1rem 1rem 0 0;
  border-bottom: none;
}

/* Offcanvas Styles */
.offcanvas {
  background-color: var(--light-color);
  color: var(--text-dark);
  border: none;
}

[data-theme="dark"] .offcanvas {
  background-color: var(--dark-secondary);
  color: var(--text-light);
}

.offcanvas-header {
  background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
  color: white;
  border-bottom: 1px solid rgba(255,255,255,0.1);
}

/* Footer Styles */
.footer-main {
  background: linear-gradient(135deg, var(--dark-primary) 0%, var(--dark-secondary) 100%);
  color: var(--text-light);
  border-top: 3px solid var(--primary-color);
  margin-top: auto;
}

.footer-main a {
  color: var(--primary-color);
  text-decoration: none;
  transition: all 0.3s ease;
}

.footer-main a:hover {
  color: #d63851;
  text-decoration: underline;
}

/* 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-in-right {
  animation: slideInRight 0.5s ease-out;
}

@keyframes slideInRight {
  from { opacity: 0; transform: translateX(50px); }
  to { opacity: 1; transform: translateX(0); }
}

/* Loading Animation */
.loading {
  position: relative;
  overflow: hidden;
}

.loading::after {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(233, 69, 96, 0.3), transparent);
  animation: loading 1.5s infinite;
}

@keyframes loading {
  0% { left: -100%; }
  100% { left: 100%; }
}

/* Responsive Design */
@media (max-width: 768px) {
  .container {
    padding-left: 15px;
    padding-right: 15px;
  }
  
  .card {
    margin-bottom: 1rem;
    border-radius: 0.75rem;
  }
  
  .btn-lg {
    padding: 0.75rem 1.5rem;
    font-size: 1rem;
  }
  
  .result-value .display-4 {
    font-size: 2.5rem;
  }
  
  .zone-percentage {
    font-size: 1.75rem;
  }
  
  .zone-weight {
    font-size: 1.25rem;
  }
  
  .history-details {
    flex-direction: column;
    gap: 0.25rem;
  }
  
  .header-main h1 {
    font-size: 1.5rem;
  }
}

@media (max-width: 576px) {
  .zone-card {
    padding: 1rem;
  }
  
  .result-value {
    padding: 0.75rem;
  }
  
  .result-value .display-4 {
    font-size: 2rem;
  }
  
  .card-body {
    padding: 1rem;
  }
  
  .btn {
    font-size: 0.9rem;
  }
}

/* High Contrast Mode Support */
@media (prefers-contrast: high) {
  .card {
    border: 2px solid var(--text-dark);
  }
  
  .btn-primary {
    border: 2px solid var(--text-dark);
  }
  
  .form-control, .form-select {
    border-width: 2px;
  }
}

/* Reduced Motion Support */
@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* Print Styles */
@media print {
  .header-main,
  .footer-main,
  .btn,
  .offcanvas,
  .modal {
    display: none !important;
  }
  
  .card {
    border: 1px solid #000;
    box-shadow: none;
    page-break-inside: avoid;
  }
  
  body {
    background: white !important;
    color: black !important;
  }
}

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

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

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

::-webkit-scrollbar-thumb:hover {
  background: #d63851;
}

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

/* Toast Notifications */
.toast-container {
  position: fixed;
  top: 20px;
  right: 20px;
  z-index: 1050;
}

.toast {
  background-color: var(--light-color);
  border: 1px solid var(--border-color);
  border-radius: 0.75rem;
  box-shadow: var(--shadow-lg);
}

[data-theme="dark"] .toast {
  background-color: var(--dark-secondary);
  border-color: #495057;
  color: var(--text-light);
}

.toast-success {
  border-left: 4px solid #198754;
}

.toast-error {
  border-left: 4px solid #dc3545;
}

.toast-warning {
  border-left: 4px solid #fd7e14;
}

/* Chart Container */
#effortChart {
  max-width: 100%;
  height: auto;
  border-radius: 0.5rem;
  background-color: var(--light-color);
}

[data-theme="dark"] #effortChart {
  background-color: var(--dark-primary);
}

/* Utility Classes */
.text-gradient {
  background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  font-weight: 700;
}

.bg-gradient-primary {
  background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
}

.border-gradient {
  border: 2px solid;
  border-image: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%) 1;
}

/* Loading Spinner */
.spinner {
  width: 2rem;
  height: 2rem;
  border: 0.25rem solid rgba(233, 69, 96, 0.2);
  border-radius: 50%;
  border-top-color: var(--primary-color);
  animation: spin 1s linear infinite;
}

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