/* CSS Variables for Theme Management */
[data-theme="light"] {
  --bg-color: #ffffff;
  --text-color: #1a1a1a;
  --text-primary: #000000;
  --text-secondary: #666666;
  --bg-primary: #f8f9fa;
  --bg-secondary: #e9ecef;
  --border-color: #dee2e6;
  --accent-color: #0d6efd;
  --accent-hover: #0b5ed7;
  --button-bg: #f8f9fa;
  --button-hover: #e9ecef;
  --button-active: #0d6efd;
  --shadow: rgba(0, 0, 0, 0.1);
  --shadow-heavy: rgba(0, 0, 0, 0.2);
}

:root {
  --bg-primary: #ffffff;
  --bg-secondary: #f8f9fa;
  --text-primary: #212529;
  --text-secondary: #6c757d;
  --border-color: #dee2e6;
  --button-bg: #e9ecef;
  --button-hover: #dee2e6;
  --button-active: #007bff;
  --shadow: rgba(0, 0, 0, 0.1);
  --shadow-heavy: rgba(0, 0, 0, 0.15);
}

[data-theme="dark"] {
  --bg-color: #1a1a1a;
  --text-color: #e0e0e0;
  --text-primary: #ffffff;
  --text-secondary: #b0b0b0;
  --bg-primary: #2a2a2a;
  --bg-secondary: #3a3a3a;
  --border-color: #404040;
  --accent-color: #6366f1;
  --accent-hover: #4f46e5;
  --button-bg: #2a2a2a;
  --button-hover: #3a3a3a;
  --button-active: #6366f1;
  --shadow: rgba(0, 0, 0, 0.3);
  --shadow-heavy: rgba(0, 0, 0, 0.5);
}

/* Reset and Base Styles */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background-color: var(--bg-primary);
  color: var(--text-primary);
  transition: background-color 0.3s ease, color 0.3s ease;
  overflow: hidden;
}

.app {
  height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Header Controls */
.controls {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 20px;
  background-color: var(--bg-secondary);
  border-bottom: 1px solid var(--border-color);
  box-shadow: 0 2px 4px var(--shadow);
  z-index: 100;
}

.control-group,
.download-group {
  display: flex;
  gap: 8px;
  align-items: center;
}

.control-btn,
.format-btn {
  padding: 12px 20px;
  border: 1px solid var(--border-color);
  border-radius: 6px;
  background: var(--bg-primary);
  color: var(--text-primary);
  cursor: pointer;
  transition: all 0.2s ease;
  font-size: 14px;
  font-weight: 600;
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  box-shadow: 0 2px 4px var(--shadow);
}

.download-btn {
  padding: 12px 20px;
  border: 2px solid var(--text-primary);
  border-radius: 6px;
  background: var(--text-primary);
  color: var(--bg-primary);
  cursor: pointer;
  transition: all 0.2s ease;
  font-size: 14px;
  font-weight: 700;
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  box-shadow: 0 2px 4px var(--shadow);
  position: relative;
  overflow: hidden;
}

.download-btn:hover {
  background: var(--bg-primary);
  color: var(--text-primary);
  transform: translateY(-1px);
  box-shadow: 0 4px 8px var(--shadow-heavy);
}

.download-btn:active {
  transform: scale(0.95);
}

.nav-btn {
  padding: 14px 24px;
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  color: var(--text-primary);
  cursor: pointer;
  transition: all 0.2s ease;
  font-size: 15px;
  font-weight: 600;
  min-width: 120px;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  box-shadow: 0 2px 4px var(--shadow);
}

.nav-btn:hover {
  background: var(--text-primary);
  border-color: var(--text-primary);
  color: var(--bg-primary);
  transform: translateY(-1px);
  box-shadow: 0 4px 8px var(--shadow-heavy);
}

.nav-btn:active {
  transform: scale(0.95);
}

.nav-btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  transform: none;
  background: var(--button-bg);
}

.nav-btn:disabled:hover {
  background: var(--bg-primary);
  border-color: var(--border-color);
  color: var(--text-primary);
  box-shadow: 0 2px 4px var(--shadow);
  transform: none;
}

.control-btn:hover,
.format-btn:hover,
.font-btn:hover {
  background: var(--text-primary);
  color: var(--bg-primary);
  border-color: var(--text-primary);
  transform: translateY(-1px);
}

.control-btn:active,
.format-btn:active {
  transform: scale(0.95);
}

.format-btn.active {
  background: var(--text-primary);
  color: var(--bg-primary);
  border-color: var(--text-primary);
}

.format-selector {
  display: flex;
  background: var(--bg-secondary);
  border-radius: 8px;
  padding: 12px 16px;
  justify-content: center;
}

.format-label {
  color: var(--text-primary);
  font-weight: 600;
  font-size: 14px;
}

/* Main Viewer Container */
.viewer-container {
  flex: 1;
  position: relative;
  overflow: hidden;
}

.viewer {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  display: none;
  flex-direction: column;
}

.viewer.active {
  display: flex;
}

/* PDF Viewer Styles */
.pdf-controls,
.epub-controls {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 16px;
  padding: 12px;
  background-color: var(--bg-secondary);
  border-bottom: 1px solid var(--border-color);
}

.page-info,
.chapter-info {
  font-size: 14px;
  color: var(--text-secondary);
  min-width: 80px;
  text-align: center;
}

.font-controls {
  display: flex;
  align-items: center;
  gap: 8px;
}

.pdf-container {
  flex: 1;
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 10px;
  overflow: hidden;
  width: 100%;
  height: 100%;
  background-color: var(--bg-primary);
}

#pdf-canvas {
  max-width: 100%;
  max-height: 100%;
  width: auto;
  height: auto;
  border: 1px solid var(--border-color);
  border-radius: 8px;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
  object-fit: contain;
}

/* Responsive design for different screen sizes */
@media (max-width: 768px) {
  .pdf-container {
    padding: 5px;
  }
  
  .pdf-controls {
    flex-wrap: wrap;
    gap: 8px;
    padding: 10px;
  }
  
  .nav-btn {
    min-width: 100px;
    padding: 12px 16px;
    font-size: 14px;
  }
  
  .page-info {
    font-size: 14px;
  }
}

@media (max-width: 480px) {
  .pdf-container {
    padding: 2px;
  }
  
  .nav-btn {
    min-width: 80px;
    padding: 10px 12px;
    font-size: 13px;
  }
  
  .pdf-controls {
    padding: 8px;
    gap: 6px;
  }
}

@media (min-width: 1200px) {
  .pdf-container {
    padding: 20px;
  }
}

/* Fullscreen Mode */
body.fullscreen-mode {
  margin: 0;
  padding: 0;
  overflow: hidden;
}

body.fullscreen-mode .viewer-container {
  height: 100vh;
  padding: 0;
  margin: 0;
}

body.fullscreen-mode .pdf-container {
    height: 100vh;
    padding: 0;
    margin: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg-color);
}

body.fullscreen-mode #pdf-canvas {
  max-height: 100vh;
  max-width: 100vw;
  cursor: pointer;
}

/* Loading Indicator */
.loading {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: var(--bg-primary);
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  z-index: 1000;
}

.loading.hidden {
  display: none;
}

.spinner {
  width: 40px;
  height: 40px;
  border: 4px solid var(--border-color);
  border-top: 4px solid var(--button-active);
  border-radius: 50%;
  animation: spin 1s linear infinite;
  margin-bottom: 16px;
}

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

.loading p {
  color: var(--text-secondary);
  font-size: 16px;
}

/* Responsive Design */
@media (max-width: 768px) {
  .controls {
    padding: 8px 12px;
    flex-wrap: wrap;
    gap: 8px;
  }
  
  .control-group,
  .download-group {
    gap: 4px;
  }
  
  .control-btn,
  .format-btn,
  .download-btn {
    padding: 6px 8px;
    font-size: 12px;
  }
  
  .pdf-controls,
  .epub-controls {
    padding: 8px;
    gap: 8px;
    flex-wrap: wrap;
  }
  
  .pdf-container {
    padding: 10px;
  }
  
  .epub-container {
    padding: 0 10px;
  }
}

@media (max-width: 480px) {
  .controls {
    padding: 6px 8px;
  }
  
  .download-group {
    flex-direction: column;
    gap: 4px;
  }
  
  .zoom-controls,
  .font-controls {
    gap: 4px;
  }
  
  .nav-btn,
  .zoom-btn,
  .font-btn {
    padding: 4px 6px;
    font-size: 12px;
  }
}

/* Fullscreen Styles */
.app.fullscreen {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  z-index: 9999;
}

.app.fullscreen .controls {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  opacity: 0;
  transition: opacity 0.3s ease;
}

.app.fullscreen:hover .controls {
  opacity: 1;
}

/* Smooth Transitions */
.viewer,
.pdf-container,
.epub-container {
  transition: all 0.3s ease;
}

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

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

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

::-webkit-scrollbar-thumb:hover {
  background: var(--text-secondary);
}

/* Focus Styles for Accessibility */
.control-btn:focus,
.format-btn:focus,
.download-btn:focus,
.nav-btn:focus,
.zoom-btn:focus,
.font-btn:focus {
  outline: 2px solid var(--button-active);
  outline-offset: 2px;
}