/* CSS Variables for Theme Management */
:root {
  --bg-primary: #FFFFFF;
  --bg-secondary: #F8F9FA;
  --bg-tertiary: #E9ECEF;
  --border-color: #DEE2E6;
  --text-primary: #212529;
  --text-secondary: #6c757d;
  --button-number: #F8F9FA;
  --button-operator: #E9ECEF;
  --button-function: #DEE2E6;
  --button-equals: #212529;
  --button-hover: rgba(0, 0, 0, 0.1);
  --shadow-light: 0 2px 4px rgba(0, 0, 0, 0.1);
  --shadow-medium: 0 4px 8px rgba(0, 0, 0, 0.15);
}

/* Dark Theme Variables */
[data-theme="dark"] {
  --bg-primary: #212529;
  --bg-secondary: #343a40;
  --bg-tertiary: #495057;
  --border-color: #6c757d;
  --text-primary: #FFFFFF;
  --text-secondary: #adb5bd;
  --button-number: #495057;
  --button-operator: #6c757d;
  --button-function: #adb5bd;
  --button-equals: #FFFFFF;
  --button-hover: rgba(255, 255, 255, 0.1);
  --shadow-light: 0 2px 4px rgba(0, 0, 0, 0.3);
  --shadow-medium: 0 4px 8px rgba(0, 0, 0, 0.4);
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  background-color: var(--bg-secondary);
  color: var(--text-primary);
  transition: background-color 0.3s ease, color 0.3s ease;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

main {
  flex: 1;
}

/* Header Styles */
.navbar {
  background-color: var(--bg-primary) !important;
  border-bottom: 1px solid var(--border-color) !important;
  box-shadow: var(--shadow-light);
}

.navbar-brand {
  color: var(--text-primary) !important;
  font-weight: 600;
}

.navbar-brand i {
  margin-right: 0.5rem;
  color: #007bff;
}

/* Dark Mode Toggle */
.form-check-input:checked {
  background-color: #007bff;
  border-color: #007bff;
}

.form-check-label i {
  color: var(--text-secondary);
  transition: color 0.3s ease;
}

/* Calculator Container */
.calculator-container {
  background-color: var(--bg-primary);
  border-radius: 1rem;
  padding: 1.5rem;
  box-shadow: var(--shadow-medium);
  border: 1px solid var(--border-color);
  transition: all 0.3s ease;
}

/* Calculator Display */
.calculator-display {
  background-color: var(--bg-tertiary);
  border-radius: 0.75rem;
  padding: 1.5rem;
  border: 1px solid var(--border-color);
  min-height: 120px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.display-expression {
  font-size: 1rem;
  color: var(--text-secondary);
  text-align: right;
  min-height: 1.5rem;
  word-break: break-all;
  overflow-wrap: break-word;
}

.display-result {
  font-size: 2.5rem;
  font-weight: 600;
  color: var(--text-primary);
  text-align: right;
  cursor: pointer;
  transition: color 0.2s ease;
  word-break: break-all;
  overflow-wrap: break-word;
}

.display-result:hover {
  color: #007bff;
}

/* Calculator Buttons */
.calculator-buttons .btn {
  height: 60px;
  font-size: 1.25rem;
  font-weight: 600;
  border-radius: 0.75rem;
  border: 1px solid var(--border-color);
  transition: all 0.2s ease;
  position: relative;
  overflow: hidden;
}

.calculator-buttons .btn:before {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, var(--button-hover), transparent);
  transition: left 0.5s;
}

.calculator-buttons .btn:hover:before {
  left: 100%;
}

/* Button Types */
.btn-number {
  background-color: var(--button-number);
  color: var(--text-primary);
  border-color: var(--border-color);
}

.btn-number:hover,
.btn-number:focus {
  background-color: var(--button-operator);
  color: var(--text-primary);
  border-color: var(--border-color);
  transform: translateY(-2px);
  box-shadow: var(--shadow-light);
}

.btn-operator {
  background-color: var(--button-operator);
  color: var(--text-primary);
  border-color: var(--border-color);
}

.btn-operator:hover,
.btn-operator:focus {
  background-color: var(--button-function);
  color: var(--text-primary);
  border-color: var(--border-color);
  transform: translateY(-2px);
  box-shadow: var(--shadow-light);
}

.btn-function {
  background-color: var(--button-function);
  color: var(--text-primary);
  border-color: var(--border-color);
}

.btn-function:hover,
.btn-function:focus {
  background-color: var(--text-secondary);
  color: var(--bg-primary);
  border-color: var(--text-secondary);
  transform: translateY(-2px);
  box-shadow: var(--shadow-light);
}

.btn-equals {
  background-color: #007bff;
  color: white;
  border-color: #007bff;
}

.btn-equals:hover,
.btn-equals:focus {
  background-color: #0056b3;
  color: white;
  border-color: #0056b3;
  transform: translateY(-2px);
  box-shadow: 0 4px 8px rgba(0, 123, 255, 0.3);
}

/* Button Active States */
.calculator-buttons .btn:active {
  transform: translateY(0);
  box-shadow: inset 0 2px 4px var(--button-hover);
}

/* Responsive Button Sizing */
@media (max-width: 576px) {
  .calculator-buttons .btn {
    height: 55px;
    font-size: 1.1rem;
  }
  
  .display-result {
    font-size: 2rem;
  }
  
  .calculator-container {
    padding: 1rem;
  }
}

@media (min-width: 768px) {
  .calculator-buttons .btn {
    height: 65px;
    font-size: 1.3rem;
  }
  
  .display-result {
    font-size: 3rem;
  }
}

/* Modal Styles */
.modal-content {
  background-color: var(--bg-primary);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
}

.modal-header {
  border-bottom: 1px solid var(--border-color);
}

.modal-title i {
  color: #007bff;
  margin-right: 0.5rem;
}



/* Offcanvas Styles */
.offcanvas {
  background-color: var(--bg-primary);
  color: var(--text-primary);
  border-left: 1px solid var(--border-color);
}

.offcanvas-header {
  border-bottom: 1px solid var(--border-color);
}

.offcanvas-title i {
  color: #007bff;
  margin-right: 0.5rem;
}

/* History Styles */
.history-item {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 0.5rem;
  padding: 1rem;
  margin-bottom: 0.75rem;
  cursor: pointer;
  transition: all 0.2s ease;
}

.history-item:hover {
  background-color: var(--bg-tertiary);
  transform: translateY(-1px);
  box-shadow: var(--shadow-light);
}

.history-expression {
  font-size: 0.9rem;
  color: var(--text-secondary);
  margin-bottom: 0.25rem;
}

.history-result {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 0.25rem;
}

.history-time {
  font-size: 0.75rem;
  color: var(--text-secondary);
}

/* Ad Styles */
.ad-banner,
.admob-banner {
  text-align: center;
  background-color: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: 0.5rem;
  padding: 1rem;
  margin: 1rem 0;
}

.ad-placeholder {
  padding: 2rem;
  background-color: var(--bg-secondary);
  border: 2px dashed var(--border-color);
  border-radius: 0.5rem;
  color: var(--text-secondary);
}

/* Footer Styles */
footer {
  background-color: var(--bg-primary) !important;
  border-top: 1px solid var(--border-color) !important;
  color: var(--text-secondary);
  margin-top: auto;
}

footer a {
  color: #007bff;
}

footer a:hover {
  color: #0056b3;
}

/* Accordion Styles */
.accordion-item {
  background-color: var(--bg-primary);
  border: 1px solid var(--border-color);
}

.accordion-button {
  background-color: var(--bg-secondary);
  color: var(--text-primary);
  border: none;
}

.accordion-button:not(.collapsed) {
  background-color: var(--bg-tertiary);
  color: var(--text-primary);
  box-shadow: none;
}

.accordion-body {
  background-color: var(--bg-primary);
  color: var(--text-primary);
}

/* Button Group Styles */
.btn-group .btn-outline-primary {
  color: var(--text-primary);
  border-color: var(--border-color);
}

.btn-group .btn-outline-primary:hover {
  background-color: #007bff;
  border-color: #007bff;
  color: white;
}

.btn-group .btn-check:checked + .btn-outline-primary {
  background-color: #007bff;
  border-color: #007bff;
  color: white;
}

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

.fade-in {
  animation: fadeIn 0.3s ease;
}

@keyframes pulse {
  0% {
    transform: scale(1);
  }
  50% {
    transform: scale(1.05);
  }
  100% {
    transform: scale(1);
  }
}

.pulse {
  animation: pulse 0.2s ease;
}

/* Loading States */
.loading {
  position: relative;
  pointer-events: none;
}

.loading::after {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  width: 20px;
  height: 20px;
  margin: -10px 0 0 -10px;
  border: 2px solid var(--border-color);
  border-top-color: #007bff;
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

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

/* Accessibility Improvements */
.btn:focus {
  outline: 2px solid #007bff;
  outline-offset: 2px;
}

.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;
}

/* High Contrast Mode Support */
@media (prefers-contrast: high) {
  :root {
    --shadow-light: 0 2px 4px rgba(0, 0, 0, 0.3);
    --shadow-medium: 0 4px 8px rgba(0, 0, 0, 0.4);
  }
  
  .calculator-buttons .btn {
    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 {
  .navbar,
  .offcanvas,
  .modal,
  .ad-banner,
  .admob-banner,
  footer {
    display: none !important;
  }
  
  .calculator-container {
    box-shadow: none;
    border: 1px solid #000;
  }
}