/* === FONT & THEME VARIABLES === */
:root {
  --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --hue-primary: 240; /* Indigo */
  --hue-secondary: 280; /* Magenta/Purple */
  --hue-danger: 350;  /* Red */

  /* Light Mode */
  --bg-main: #f8f9fc;
  --bg-glass: rgba(255, 255, 255, 0.5);
  --bg-card: #ffffff;
  --bg-subtle: #f1f3f8;
  --border: rgba(0, 0, 0, 0.08);
  --text-primary: #1a202c;
  --text-secondary: #5a677d;
  --shadow-color: 220, 40%, 50%;
  --primary: hsl(var(--hue-primary), 90%, 65%);
  --primary-dark: hsl(var(--hue-primary), 90%, 55%);
  --danger: hsl(var(--hue-danger), 80%, 55%);
  --grad-1: hsl(var(--hue-primary), 100%, 85%);
  --grad-2: hsl(var(--hue-secondary), 100%, 90%);
}

.dark-mode {
  --bg-main: #131824;
  --bg-glass: rgba(28, 35, 51, 0.5);
  --bg-card: #1c2333;
  --bg-subtle: #2a3346;
  --border: rgba(255, 255, 255, 0.1);
  --text-primary: #f0f4f9;
  --text-secondary: #a0aec0;
  --shadow-color: 220, 40%, 0%;
  --primary: hsl(var(--hue-primary), 80%, 70%);
  --primary-dark: hsl(var(--hue-primary), 80%, 80%);
  --danger: hsl(var(--hue-danger), 70%, 60%);
  --grad-1: hsl(var(--hue-primary), 80%, 20%);
  --grad-2: hsl(var(--hue-secondary), 80%, 25%);
}

/* === BASE & LAYOUT === */
* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  font-family: var(--font-family);
  background-color: var(--bg-main);
  color: var(--text-primary);
  transition: background-color 0.3s;
  font-size: 16px;
  overflow: hidden;
  position: relative;
  -webkit-tap-highlight-color: transparent; /* Native feel: remove tap highlight */
}
/* Premium Aurora Gradient Background */
body::before, body::after {
  content: ''; position: fixed; z-index: -1;
  border-radius: 50%; filter: blur(150px);
  transition: background-color 0.5s;
}
body::before { width: 500px; height: 500px; background: var(--grad-1); top: -20%; left: -10%; animation: pulse 15s infinite alternate; }
body::after { width: 600px; height: 600px; background: var(--grad-2); bottom: -25%; right: -15%; animation: pulse 20s infinite alternate-reverse; }
@keyframes pulse { from { transform: scale(0.8); } to { transform: scale(1.2); } }

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

/* === SIDEBAR (Desktop) === */
.sidebar {
  width: 280px;
  background-color: var(--bg-glass);
  backdrop-filter: blur(30px) saturate(180%);
  border-right: 1px solid var(--border);
  flex-shrink: 0;
  display: flex; flex-direction: column; height: 100vh;
  box-shadow: inset -1px 0 0 var(--border);
  transition: width 0.3s ease, transform 0.3s ease;
}
.sidebar-content { overflow-y: auto; padding: 1.5rem; display: flex; flex-direction: column; flex-grow: 1; }
.sidebar-header { margin-bottom: 2rem; }
.site-logo { height: 40px; margin-bottom: 0.75rem; }
.sidebar h1 { font-size: 1.3rem; font-weight: 600; }
.action-section { margin-bottom: 2rem; }
.action-section h2 { font-size: 0.75rem; text-transform: uppercase; letter-spacing: 1px; color: var(--text-secondary); margin-bottom: 0.75rem; font-weight: 600; }
.sidebar-btn { display: flex; align-items: center; gap: 0.75rem; width: 100%; padding: 0.75rem; margin-bottom: 0.5rem; font-size: 0.95rem; font-weight: 500; text-align: left; border: 1px solid transparent; border-radius: 8px; background-color: rgba(128,128,128,0.1); color: var(--text-primary); cursor: pointer; transition: all 0.2s; }
.sidebar-btn:hover { border-color: var(--primary); color: var(--primary); background-color: var(--bg-subtle); transform: translateY(-2px); box-shadow: 0 4px 10px rgba(var(--shadow-color), 0.1); }
.sidebar-btn:disabled { opacity: 0.6; cursor: not-allowed; background-color: transparent; border-color: var(--border); color: var(--text-secondary); transform: none; box-shadow: none; }
.sidebar-btn.primary { background-color: var(--primary); color: white; border-color: var(--primary); }
.sidebar-btn.primary:hover { background-color: var(--primary-dark); border-color: var(--primary-dark); }
.sidebar-btn.danger:hover { background-color: var(--danger); color: white; border-color: var(--danger); }
.sidebar-btn i { font-size: 1.1rem; width: 20px; text-align: center; }
.sidebar-footer { margin-top: auto; }

/* Click-Activated Dropdowns (Desktop) */
.dropdown-container { position: relative; }
.upload-dropdown {
  position: absolute; bottom: calc(100% + 8px); left: 0;
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: 8px; box-shadow: 0 10px 25px rgba(var(--shadow-color), 0.1);
  z-index: 10; padding: 0.5rem; width: 100%;
  opacity: 0; visibility: hidden; transform: translateY(10px);
  transition: opacity 0.2s ease, transform 0.2s ease, visibility 0.2s;
}
.upload-dropdown.visible { opacity: 1; visibility: visible; transform: translateY(0); }
.dropdown-title { font-size: 0.8rem; color: var(--text-secondary); padding: 0.2rem 0.8rem; margin-bottom: 0.25rem; }
.dropdown-item { width: 100%; background: none; border: none; text-align: left; padding: 0.6rem 0.8rem; font-size: 0.9rem; font-weight: 500; color: var(--text-primary); cursor: pointer; display: flex; align-items: center; gap: 0.7rem; transition: background-color 0.2s; border-radius: 6px; }
.dropdown-item:hover { background-color: var(--bg-subtle); color: var(--primary); }

/* === MAIN CONTENT === */
.main-content { flex: 1; display: flex; flex-direction: column; height: 100vh; }
.main-header {
  padding: 1.5rem; border-bottom: 1px solid var(--border);
  display: flex; justify-content: space-between; align-items: center;
  flex-shrink: 0; background-color: var(--bg-glass);
  backdrop-filter: blur(30px) saturate(180%);
  box-shadow: inset 0 -1px 0 var(--border);
}
.header-left { display: flex; align-items: center; gap: 1.5rem; }
.pages-count { background-color: var(--bg-card); color: var(--text-primary); padding: 0.5rem 1rem; border-radius: 25px; font-weight: 600; font-size: 0.9rem; display: flex; align-items: center; gap: 0.5rem; border: 1px solid var(--border); }
.pages-grid-container { flex-grow: 1; overflow-y: auto; padding: 1.5rem; }
.pages-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 1.5rem; }

/* === Master Ratio Control === */
.master-ratio-control {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  flex-grow: 1;
  justify-content: center;
  margin: 0 1rem;
}
.master-ratio-control input {
  padding: 0.5rem 0.75rem;
  border: 1px solid var(--border);
  border-radius: 6px;
  font-size: 0.9rem;
  background-color: var(--bg-card);
  color: var(--text-primary);
  outline: none;
  transition: border-color 0.2s;
  width: 150px;
}
.master-ratio-control input:focus {
  border-color: var(--primary);
}
.master-ratio-control button {
  padding: 0.5rem 1rem;
  border: none;
  border-radius: 6px;
  background-color: var(--primary);
  color: white;
  font-weight: 500;
  font-size: 0.9rem;
  cursor: pointer;
  transition: background-color 0.2s;
}
.master-ratio-control button:hover {
  background-color: var(--primary-dark);
}

/* === Attractive Empty State === */
.empty-grid-placeholder {
  grid-column: 1 / -1; display: flex; flex-direction: column; align-items: center;
  justify-content: center; text-align: center; padding: 4rem 2rem;
  border-radius: 16px; color: var(--text-secondary);
  background-color: var(--bg-glass); border: 1px solid var(--border);
}
.empty-grid-placeholder .empty-icon {
  font-size: 3.5rem; margin-bottom: 1.5rem; color: var(--primary);
  background-color: var(--bg-card); width: 80px; height: 80px;
  border-radius: 50%; display: flex; align-items: center; justify-content: center;
  box-shadow: 0 5px 15px rgba(var(--shadow-color), 0.1);
}
.empty-grid-placeholder h3 { font-size: 1.5rem; color: var(--text-primary); margin-bottom: 0.5rem; }
.empty-grid-placeholder p { max-width: 350px; }
.empty-grid-btn {
  margin-top: 1.5rem; padding: 0.8rem 1.5rem; font-size: 1rem; font-weight: 600;
  background-color: var(--primary); color: white; border: none; border-radius: 8px;
  cursor: pointer; transition: all 0.2s; display: flex; align-items: center; gap: 0.5rem;
}
.empty-grid-btn:hover { background-color: var(--primary-dark); transform: translateY(-2px); box-shadow: 0 4px 15px rgba(var(--shadow-color), 0.2); }

/* Theme Switcher */
.theme-switcher { display: flex; align-items: center; gap: 0.5rem; }
.switch { position: relative; display: inline-block; width: 44px; height: 24px; }
.switch input { opacity: 0; width: 0; height: 0; }
.slider { position: absolute; cursor: pointer; top: 0; left: 0; right: 0; bottom: 0; background-color: var(--border); transition: 0.2s; border-radius: 24px; }
.slider:before { position: absolute; content: ""; height: 18px; width: 18px; left: 3px; bottom: 3px; background-color: white; transition: 0.2s; border-radius: 50%; }
input:checked + .slider { background-color: var(--primary); }
input:checked + .slider:before { transform: translateX(20px); }

/* === PAGE THUMBNAIL === */
.page-thumb { background-color: var(--bg-card); border: 1px solid var(--border); border-radius: 12px; box-shadow: 0 4px 12px rgba(var(--shadow-color), 0.05); display: flex; flex-direction: column; position: relative; transition: all 0.2s; cursor: grab; user-select: none; }
.page-thumb:active { cursor: grabbing; }
.page-thumb.sortable-chosen { transform: scale(1.03); box-shadow: 0 8px 20px rgba(var(--shadow-color), 0.15); border-color: var(--primary); }
.thumb-header { position: relative; }
.page-thumb img { width: 100%; height: auto; aspect-ratio: 3/4; object-fit: contain; background-color: var(--bg-subtle); border-radius: 11px 11px 0 0; box-shadow: inset 0 0 10px rgba(0,0,0,0.05); }
.page-num { position: absolute; top: 8px; left: 8px; background-color: var(--primary); color: white; height: 28px; width: 28px; border-radius: 50%; display: flex; align-items: center; justify-content: center; font-size: 0.9rem; font-weight: 600; border: 2px solid var(--bg-card); }
.thumb-body { padding: 0.75rem; }
.thumb-actions { display: grid; grid-template-columns: repeat(5, 1fr); gap: 0.5rem; }
.thumb-btn { background: var(--bg-subtle); color: var(--text-secondary); border: none; border-radius: 6px; padding: 0.6rem; font-size: 1rem; cursor: pointer; transition: all 0.2s; }
.thumb-btn:hover { background-color: var(--primary); color: white; }
.thumb-btn.danger:hover { background-color: var(--danger); }

/* Resize Controls */
.size-controls { margin-top: 0.75rem; padding-top: 0.75rem; border-top: 1px solid var(--border); display: none; animation: fadeIn 0.3s; }
.size-controls.visible { display: block; }
@keyframes fadeIn { from { opacity: 0; } to { opacity: 1; } }
.size-inputs { display: flex; gap: 0.75rem; }
.size-input-group { flex: 1; }
.size-input-group label { font-size: 0.8rem; font-weight: 500; display: block; margin-bottom: 0.25rem; color: var(--text-secondary); }
.size-input-group input { width: 100%; padding: 0.5rem; border: 1px solid var(--border); border-radius: 6px; font-size: 0.9rem; background-color: var(--bg-card); color: var(--text-primary); outline: none; transition: border-color 0.2s; }
.size-input-group input:focus { border-color: var(--primary); }

/* Aspect Ratio Control */
.aspect-ratio-control {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-top: 0.75rem;
  padding-top: 0.75rem;
  border-top: 1px solid var(--border);
}
.aspect-ratio-control label {
  font-size: 0.85rem;
  color: var(--text-secondary);
  cursor: pointer;
}
.aspect-ratio-control input[type="checkbox"] {
  cursor: pointer;
  width: 16px;
  height: 16px;
}

/* === MODALS === */
.modal-overlay { position: fixed; top: 0; left: 0; width: 100%; height: 100%; background: rgba(0, 0, 0, 0.3); backdrop-filter: blur(10px) saturate(150%); display: flex; align-items: center; justify-content: center; z-index: 1000; }
.modal { background: var(--bg-glass); border: 1px solid var(--border); border-radius: 12px; padding: 2rem; max-width: 450px; width: 90%; box-shadow: 0 10px 30px rgba(0,0,0,0.2); animation: modalSlide 0.3s ease-out; text-align: center; }
@keyframes modalSlide { from { transform: translateY(-20px) scale(0.95); opacity: 0; } to { transform: translateY(0) scale(1); opacity: 1; } }
.modal h3 { margin-bottom: 0.5rem; font-size: 1.25rem; }
.modal p { margin-bottom: 1.5rem; color: var(--text-secondary); }
.modal input { width: 100%; padding: 0.7rem; font-size: 1rem; margin-bottom: 0.5rem; border-radius: 8px; border: 1px solid var(--border); background-color: var(--bg-subtle); color: var(--text-primary); }
.modal #password-error, .modal #move-error { color: var(--danger); margin-bottom: 1rem; font-size: 0.9rem; display: none; }
.modal-actions { display: flex; gap: 1rem; justify-content: center; margin-top: 1rem; }
.modal-actions button { padding: 0.7rem 1.4rem; border-radius: 8px; font-size: 1rem; font-weight: 600; cursor: pointer; transition: all 0.2s; outline: none; border: none; }
.btn-cancel { background-color: var(--bg-subtle); color: var(--text-primary); }
.btn-cancel:hover { background-color: var(--border); }
.btn-export { background-color: var(--primary); color: #fff; }
.btn-export:hover { opacity: 0.85; }

/* === Mobile Action Sheets === */
.action-sheet-overlay { position: fixed; top: 0; left: 0; width: 100%; height: 100%; background: rgba(0,0,0,0.5); z-index: 1050; opacity: 0; visibility: hidden; transition: opacity 0.3s; }
.action-sheet-overlay.visible { opacity: 1; visibility: visible; }
.mobile-action-sheet { position: fixed; bottom: 0; left: 0; width: 100%; z-index: 1060; transform: translateY(100%); transition: transform 0.3s ease-out; }
.mobile-action-sheet.visible { transform: translateY(0); }
.action-sheet-content { background: var(--bg-card); border-radius: 16px 16px 0 0; padding: 1rem; display: flex; flex-direction: column; gap: 0.5rem; }
.action-sheet-title { font-size: 0.9rem; text-align: center; color: var(--text-secondary); padding: 0.5rem; }
.action-sheet-btn { width: 100%; background: var(--bg-subtle); border: none; text-align: left; padding: 1rem; font-size: 1rem; font-weight: 500; color: var(--text-primary); cursor: pointer; display: flex; align-items: center; gap: 1rem; border-radius: 8px; }
.action-sheet-btn:hover { background-color: var(--border); }
.action-sheet-btn.cancel { margin-top: 0.5rem; background: var(--bg-subtle); font-weight: 600; color: var(--primary); justify-content: center; }
.action-sheet-btn.danger { color: var(--danger); }

/* === Dedicated Mobile Navigation Bar === */
.mobile-nav {
  display: none; /* Hidden by default */
  position: fixed;
  bottom: 0;
  left: 0;
  width: 100%;
  background-color: var(--bg-glass);
  backdrop-filter: blur(30px) saturate(180%);
  border-top: 1px solid var(--border);
  z-index: 50;
  align-items: center;
  justify-content: space-around;
  padding: 0 0.5rem;
  /* === NEW: Native feel for iPhone notch === */
  height: calc(80px + env(safe-area-inset-bottom));
  padding-bottom: env(safe-area-inset-bottom);
}
.mobile-nav-btn {
  background: none;
  border: none;
  color: var(--text-secondary);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 4px;
  font-size: 0.7rem;
  font-family: var(--font-family);
  cursor: pointer;
  height: 100%;
  padding: 0.5rem;
  border-radius: 8px;
  flex-grow: 1;
  transition: background-color 0.2s, color 0.2s;
}
.mobile-nav-btn:hover {
  background-color: var(--bg-subtle);
  color: var(--text-primary);
}
.mobile-nav-btn i {
  font-size: 1.2rem;
}
.mobile-nav-btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  color: var(--text-secondary);
  background-color: transparent;
}

/* === RESPONSIVE DESIGN: Tablet & Mobile === */
@media (max-width: 900px) {
  .app-layout { flex-direction: column; }
  .main-content { height: calc(100vh - 80px - env(safe-area-inset-bottom)); }
  .pages-grid-container { padding-bottom: calc(80px + env(safe-area-inset-bottom)); }
  
  .sidebar { display: none; }
  .mobile-nav { display: flex; }

  .pages-grid { grid-template-columns: repeat(auto-fill, minmax(180px, 1fr)); }

  .main-header {
    flex-wrap: wrap;
    row-gap: 1rem;
  }
  
  .master-ratio-control {
    width: 100%;
    order: 3;
    margin: 0;
    flex-grow: 0;
  }
}

@media (max-width: 600px) {
  .pages-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 1rem;
  }
  .thumb-actions {
    gap: 0.25rem;
  }
  .thumb-btn {
    padding: 0.5rem;
    font-size: 0.9rem;
  }
}

@media (max-width: 480px) {
  .pages-grid-container { padding: 1rem 1rem calc(80px + env(safe-area-inset-bottom)) 1rem; }
  .main-header { padding: 1rem; }
  .header-left { flex-wrap: wrap; gap: 0.5rem; }
  .pages-grid { grid-template-columns: 1fr; }
}

/* === Full-Screen Loader === */
#loader-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.3);
  backdrop-filter: blur(10px) saturate(150%);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1100;
}
.loader-content {
  background: var(--bg-card);
  padding: 2rem 3rem;
  border-radius: 12px;
  text-align: center;
  box-shadow: 0 10px 30px rgba(0,0,0,0.2);
}
.loader-content i {
  font-size: 3rem;
  color: var(--primary);
  margin-bottom: 1rem;
}
.loader-content p {
  font-size: 1.1rem;
  font-weight: 500;
  color: var(--text-primary);
}

/* === Drag & Drop Overlay (Desktop) === */
body.drag-over-active::before {
  content: 'Drop Files Anywhere to Upload';
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0,0,0,0.5);
  backdrop-filter: blur(10px);
  z-index: 2000;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2rem;
  font-weight: 600;
  color: white;
  border: 4px dashed var(--primary);
}

/* === Notification & Install Banner Style === */
.notification {
  position: fixed;
  bottom: 20px;
  left: 50%;
  transform: translateX(-50%) translateY(150%);
  background-color: var(--bg-card);
  color: var(--text-primary);
  padding: 1rem 1.5rem;
  border-radius: 8px;
  box-shadow: 0 5px 15px rgba(var(--shadow-color), 0.2);
  z-index: 2000;
  font-weight: 500;
  opacity: 0;
  visibility: hidden;
  transition: transform 0.4s ease-out, opacity 0.4s ease-out, visibility 0.4s;
  border: 1px solid var(--border);
}
.notification.show {
  transform: translateX(-50%) translateY(0);
  opacity: 1;
  visibility: visible;
}
.notification.error {
  background-color: var(--danger);
  color: white;
  border-color: var(--danger);
}

/* PWA Install Banner Specifics */
#install-banner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  width: 90%;
  max-width: 500px;
}
.install-actions {
  display: flex;
  gap: 0.5rem;
}
#install-banner button {
  padding: 0.5rem 1rem;
  font-size: 0.9rem;
  font-weight: 600;
  border-radius: 6px;
  border: none;
  cursor: pointer;
}

/* === Preview Modal Styles (with Mobile Fixes) === */
#preview-modal .preview-container {
  background-color: var(--bg-card);
  width: 95vw;
  height: 95vh;
  border-radius: 12px;
  box-shadow: 0 10px 30px rgba(0,0,0,0.2);
  display: flex;
  flex-direction: column;
  overflow: hidden;
}
.preview-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem 1.5rem;
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
  flex-wrap: wrap; /* Allow wrapping on small screens */
  gap: 1rem;
}
.preview-header h3 {
  font-size: 1.2rem;
  flex-grow: 1; /* Allow title to take space */
}
.preview-actions {
  display: flex;
  gap: 1rem;
  flex-shrink: 0; /* Prevent buttons from shrinking */
}
.preview-actions button {
  padding: 0.6rem 1.2rem;
  font-size: 0.9rem;
  gap: 0.5rem;
  display: flex;
  align-items: center;
}
.preview-content {
  flex-grow: 1;
  background-color: var(--bg-subtle);
}
#preview-frame {
  width: 100%;
  height: 100%;
  border: none;
}

/* === NEW: Mobile specific styles for preview modal === */
@media (max-width: 600px) {
  .preview-header {
    padding: 1rem;
    justify-content: center; /* Center content when it wraps */
  }
  .preview-header h3 {
    width: 100%;
    text-align: center;
    margin-bottom: 0.5rem;
  }
  .preview-actions {
    width: 100%;
    justify-content: center;
  }
  .preview-actions button {
    flex-grow: 1;
    justify-content: center;
  }
}