/* ==========================================
   S&A 4D Viewer - Modern Design System
   ========================================== */

:root {
  /* Color Palette */
  --primary: #4F46E5;
  --primary-hover: #4338CA;
  --primary-light: #6366F1;
  --secondary: #10B981;
  --secondary-hover: #059669;
  --danger: #EF4444;
  --danger-hover: #DC2626;
  --warning: #F59E0B;
  --bg-primary: #F9FAFB;
  --bg-secondary: #FFFFFF;
  --bg-card: #FFFFFF;
  --text-primary: #111827;
  --text-secondary: #6B7280;
  --border: #E5E7EB;
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);

  /* Spacing */
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;

  /* Border Radius */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;

  /* Transitions */
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-normal: 250ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 350ms cubic-bezier(0.4, 0, 0.2, 1);
}

/* ==========================================
   Reset & Base Styles
   ========================================== */

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html, body {
  height: 100%;
  overflow: hidden;
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  color: var(--text-primary);
  background: var(--bg-primary);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* ==========================================
   Modern Header
   ========================================== */

.modern-header {
  height: 70px;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0 var(--spacing-xl);
  box-shadow: var(--shadow-lg);
  position: relative;
  z-index: 100;
  animation: slideDown 0.4s cubic-bezier(0.16, 1, 0.3, 1);
}

@keyframes slideDown {
  from {
    transform: translateY(-100%);
    opacity: 0;
  }
  to {
    transform: translateY(0);
    opacity: 1;
  }
}

.header-left {
  display: flex;
  align-items: center;
  gap: var(--spacing-lg);
}

.logo {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  color: white;
  font-size: 1.5rem;
  font-weight: 700;
  letter-spacing: -0.025em;
}

.logo i {
  font-size: 1.75rem;
  animation: rotate3d 3s ease-in-out infinite;
}

@keyframes rotate3d {
  0%, 100% { transform: rotateY(0deg); }
  50% { transform: rotateY(180deg); }
}

.header-right {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
}

.model-controls {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
}

/* ==========================================
   Modern Buttons
   ========================================== */

.modern-btn {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-sm);
  padding: 0.625rem 1.25rem;
  background: white;
  color: var(--primary);
  border: none;
  border-radius: var(--radius-lg);
  font-family: 'Inter', sans-serif;
  font-size: 0.875rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-normal);
  box-shadow: var(--shadow-md);
}

.modern-btn:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-xl);
}

.modern-btn:active {
  transform: translateY(0);
}

.modern-btn.secondary {
  background: rgba(255, 255, 255, 0.2);
  color: white;
  backdrop-filter: blur(10px);
}

.modern-btn.secondary:hover {
  background: rgba(255, 255, 255, 0.3);
}

.modern-btn.danger {
  background: var(--danger);
  color: white;
}

.modern-btn.danger:hover {
  background: var(--danger-hover);
}

.icon-btn {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(255, 255, 255, 0.2);
  backdrop-filter: blur(10px);
  border: none;
  border-radius: 50%;
  color: white;
  cursor: pointer;
  transition: all var(--transition-normal);
}

.icon-btn:hover {
  background: rgba(255, 255, 255, 0.3);
  transform: rotate(180deg);
}

/* Button with Tooltip */
.button-with-tooltip {
  position: relative;
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
}

.info-tooltip {
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  cursor: help;
}

.info-tooltip > i {
  color: rgba(255, 255, 255, 0.7);
  font-size: 1rem;
  transition: color 0.2s ease;
}

.info-tooltip:hover > i {
  color: white;
}

.tooltip-content {
  position: absolute;
  top: 100%;
  right: 0;
  margin-top: 8px;
  background: white;
  border-radius: var(--radius-md);
  box-shadow: 0 10px 40px rgba(0, 0, 0, 0.2);
  padding: var(--spacing-md);
  min-width: 280px;
  opacity: 0;
  visibility: hidden;
  transform: translateY(-10px);
  transition: all 0.2s ease;
  z-index: 1000;
  border: 1px solid var(--border);
}

.info-tooltip:hover .tooltip-content {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.tooltip-title {
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--spacing-sm);
  font-size: 0.875rem;
}

.tooltip-content p {
  margin: var(--spacing-sm) 0;
  color: var(--text-secondary);
  font-size: 0.8125rem;
  line-height: 1.5;
}

.tooltip-hint {
  font-size: 0.75rem !important;
  color: var(--text-tertiary);
  font-style: italic;
}

.template-link {
  color: var(--primary);
  text-decoration: none;
  font-weight: 600;
  transition: color 0.2s ease;
}

.template-link:hover {
  color: var(--primary-dark);
  text-decoration: underline;
}

/* ==========================================
   Modern Select & Inputs
   ========================================== */

.modern-select {
  appearance: none;
  padding: 0.625rem 2.5rem 0.625rem 1rem;
  background: rgba(255, 255, 255, 0.95);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  font-family: 'Inter', sans-serif;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-primary);
  cursor: pointer;
  transition: all var(--transition-normal);
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' fill='none' viewBox='0 0 24 24' stroke='%236B7280'%3E%3Cpath stroke-linecap='round' stroke-linejoin='round' stroke-width='2' d='M19 9l-7 7-7-7'%3E%3C/path%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 0.5rem center;
  background-size: 1.25rem;
}

.modern-select:hover {
  border-color: var(--primary);
  box-shadow: var(--shadow-md);
}

.modern-select:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1);
}

.modern-input {
  width: 100%;
  padding: 0.75rem 1rem;
  background: var(--bg-secondary);
  border: 2px solid var(--border);
  border-radius: var(--radius-lg);
  font-family: 'Inter', sans-serif;
  font-size: 0.875rem;
  color: var(--text-primary);
  transition: all var(--transition-normal);
}

.modern-input:hover {
  border-color: var(--primary-light);
}

.modern-input:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1);
}

.modern-input::placeholder {
  color: var(--text-secondary);
}

/* ==========================================
   Loading Overlay
   ========================================== */

.loading-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  background: rgba(0, 0, 0, 0.6);
  backdrop-filter: blur(8px);
  display: none;
  justify-content: center;
  align-items: center;
  z-index: 9999;
  animation: fadeIn var(--transition-normal);
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

.loading-box {
  background: white;
  border-radius: var(--radius-xl);
  padding: var(--spacing-xl) 3rem;
  box-shadow: var(--shadow-xl);
  text-align: center;
  min-width: 320px;
  animation: scaleIn var(--transition-slow);
}

@keyframes scaleIn {
  from {
    transform: scale(0.9);
    opacity: 0;
  }
  to {
    transform: scale(1);
    opacity: 1;
  }
}

.loading-spinner {
  width: 48px;
  height: 48px;
  margin: 0 auto var(--spacing-md);
  border: 4px solid var(--border);
  border-top-color: var(--primary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

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

.loading-title {
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--spacing-md);
}

.progress-container {
  width: 100%;
  height: 8px;
  background: var(--bg-primary);
  border-radius: 999px;
  overflow: hidden;
  margin-bottom: var(--spacing-sm);
}

.progress-bar {
  height: 100%;
  background: linear-gradient(90deg, var(--primary), var(--primary-light));
  border-radius: 999px;
  transition: width var(--transition-normal);
}

.progress-percent {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-secondary);
}

/* ==========================================
   App Container Layout
   ========================================== */

.app-container {
  display: grid;
  grid-template-columns: 1fr;
  grid-template-rows: 1fr auto auto;
  height: calc(100vh - 70px);
  gap: 0;
  position: relative;
}

/* ==========================================
   Floating Add Task Button
   ========================================== */

.floating-add-btn {
  position: fixed;
  top: 85px;
  left: 20px;
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  padding: 1rem 1.5rem;
  background: linear-gradient(135deg, var(--primary), var(--primary-light));
  color: white;
  border: none;
  border-radius: var(--radius-xl);
  font-family: 'Inter', sans-serif;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  box-shadow: 0 10px 30px rgba(79, 70, 229, 0.4);
  z-index: 999;
  transition: all var(--transition-normal);
  animation: slideInFromLeft 0.4s cubic-bezier(0.16, 1, 0.3, 1);
}

@keyframes slideInFromLeft {
  from {
    transform: translateX(-100%);
    opacity: 0;
  }
  to {
    transform: translateX(0);
    opacity: 1;
  }
}

.floating-add-btn:hover {
  transform: translateY(-4px) scale(1.05);
  box-shadow: 0 15px 40px rgba(79, 70, 229, 0.5);
}

.floating-add-btn:active {
  transform: translateY(-2px) scale(1.02);
}

.floating-add-btn i {
  font-size: 1.25rem;
}

/* ==========================================
   Modal Overlay & Container
   ========================================== */

.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  background: rgba(0, 0, 0, 0.6);
  backdrop-filter: blur(8px);
  display: none;
  justify-content: center;
  align-items: center;
  z-index: 10000;
  animation: fadeIn var(--transition-normal);
}

.modal-overlay.active {
  display: flex;
}

.modal-container {
  background: white;
  border-radius: var(--radius-xl);
  width: 90%;
  max-width: 600px;
  max-height: 90vh;
  overflow: hidden;
  box-shadow: var(--shadow-xl);
  animation: modalSlideIn var(--transition-slow);
  display: flex;
  flex-direction: column;
}

@keyframes modalSlideIn {
  from {
    transform: scale(0.9) translateY(50px);
    opacity: 0;
  }
  to {
    transform: scale(1) translateY(0);
    opacity: 1;
  }
}

.modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--spacing-lg) var(--spacing-xl);
  background: linear-gradient(135deg, var(--primary), var(--primary-light));
  color: white;
}

.modal-header h2 {
  font-size: 1.5rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  margin: 0;
}

.modal-close-btn {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(255, 255, 255, 0.2);
  border: none;
  border-radius: 50%;
  color: white;
  font-size: 1.25rem;
  cursor: pointer;
  transition: all var(--transition-normal);
}

.modal-close-btn:hover {
  background: rgba(255, 255, 255, 0.3);
  transform: rotate(90deg);
}

.modal-body {
  padding: var(--spacing-xl);
  overflow-y: auto;
  flex: 1;
}

.modal-footer {
  display: flex;
  justify-content: flex-end;
  gap: var(--spacing-md);
  padding: var(--spacing-lg) var(--spacing-xl);
  background: var(--bg-primary);
  border-top: 1px solid var(--border);
}

/* ==========================================
   Form Elements in Modal
   ========================================== */

.form-group {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
  margin-bottom: var(--spacing-lg);
}

.form-group:last-child {
  margin-bottom: 0;
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--spacing-md);
}

.form-group label {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-primary);
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
}

.form-group label i {
  color: var(--primary);
  font-size: 1rem;
}

.form-hint {
  font-size: 0.75rem;
  color: var(--text-secondary);
  margin-top: -0.25rem;
}

.selection-info {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-md);
  background: linear-gradient(135deg, #F0F9FF, #E0F2FE);
  border-radius: var(--radius-lg);
  border: 2px solid #BAE6FD;
  font-size: 0.875rem;
  color: var(--text-primary);
  animation: fadeIn var(--transition-normal);
}

.selection-info.pulse {
  animation: pulse 0.3s ease;
}

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

.selection-info i {
  color: #0284C7;
  font-size: 1rem;
}

.selection-info strong {
  color: var(--primary);
  font-weight: 700;
  font-size: 1.125rem;
}

.modal-btn {
  padding: 0.75rem 1.5rem;
  border: none;
  border-radius: var(--radius-lg);
  font-family: 'Inter', sans-serif;
  font-size: 0.875rem;
  font-weight: 600;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  transition: all var(--transition-normal);
}

.modal-btn.primary {
  background: linear-gradient(135deg, var(--primary), var(--primary-light));
  color: white;
  box-shadow: var(--shadow-md);
}

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

.modal-btn.primary:active {
  transform: translateY(0);
}

.modal-btn.secondary {
  background: var(--bg-secondary);
  color: var(--text-secondary);
  border: 2px solid var(--border);
}

.modal-btn.secondary:hover {
  background: var(--bg-primary);
  color: var(--text-primary);
  border-color: var(--text-secondary);
}

.modal-btn.danger {
  background: var(--danger);
  color: white;
  box-shadow: var(--shadow-md);
}

.modal-btn.danger:hover {
  background: var(--danger-hover);
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

.modal-btn.danger:active {
  transform: translateY(0);
}

/* ==========================================
   Viewer Section
   ========================================== */

.viewer-section {
  position: relative;
  background: var(--bg-primary);
  overflow: hidden;
  animation: fadeIn 0.5s ease;
  min-height: 200px;
}

.viewer {
  width: 100%;
  height: 100%;
  background: linear-gradient(135deg, #F3F4F6 0%, #E5E7EB 100%);
}

/* Header Tooltips */
.header-tooltips {
  position: relative;
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-sm) var(--spacing-md);
  background: rgba(255, 255, 255, 0.15);
  backdrop-filter: blur(10px);
  border-radius: var(--radius-md);
  color: white;
  cursor: pointer;
  transition: all 0.2s ease;
  font-size: 0.875rem;
  font-weight: 500;
}

.header-tooltips:hover {
  background: rgba(255, 255, 255, 0.25);
}

.header-tooltips > i {
  color: #FCD34D;
  font-size: 1rem;
}

.tooltips-dropdown {
  position: absolute;
  top: calc(100% + 8px);
  left: 0;
  background: white;
  border-radius: var(--radius-md);
  box-shadow: 0 10px 40px rgba(0, 0, 0, 0.2);
  padding: var(--spacing-md);
  min-width: 280px;
  opacity: 0;
  visibility: hidden;
  transform: translateY(-10px);
  transition: all 0.2s ease;
  z-index: 1000;
  border: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
}

.header-tooltips:hover .tooltips-dropdown {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.help-tip-item {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  font-size: 0.8125rem;
  color: var(--text-secondary);
  padding: var(--spacing-sm) 0;
}

.help-tip-item kbd {
  background: var(--bg-primary);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 2px 6px;
  font-family: 'Inter', sans-serif;
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-primary);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.05);
  min-width: 32px;
  text-align: center;
}

.help-tip-item i {
  color: var(--primary);
  font-size: 0.875rem;
  width: 16px;
  text-align: center;
}

.help-tip-divider {
  height: 1px;
  background: var(--border);
  margin: var(--spacing-sm) 0;
}

.help-tip-note {
  align-items: flex-start;
  background: var(--bg-primary);
  padding: var(--spacing-sm);
  border-radius: var(--radius-sm);
  border-left: 3px solid var(--primary);
}

.help-tip-note i {
  margin-top: 2px;
  flex-shrink: 0;
}

.help-tip-note .fa-exclamation-triangle {
  color: #F59E0B;
}

.tip-text {
  display: flex;
  flex-direction: column;
  gap: 4px;
  line-height: 1.4;
}

.tip-text strong {
  color: var(--text-primary);
  font-weight: 600;
  font-size: 0.8125rem;
}

/* ==========================================
   Resize Handle
   ========================================== */

.resize-handle {
  grid-column: 1;
  height: 8px;
  background: var(--bg-primary);
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  cursor: ns-resize;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  z-index: 50;
  transition: all var(--transition-normal);
  user-select: none;
}

.resize-handle:hover {
  background: linear-gradient(135deg, rgba(79, 70, 229, 0.1), rgba(99, 102, 241, 0.1));
  border-color: var(--primary-light);
}

.resize-handle:active {
  background: linear-gradient(135deg, rgba(79, 70, 229, 0.2), rgba(99, 102, 241, 0.2));
  cursor: ns-resize;
}

.resize-handle-bar {
  width: 60px;
  height: 4px;
  background: var(--border);
  border-radius: 999px;
  transition: all var(--transition-normal);
}

.resize-handle:hover .resize-handle-bar {
  background: var(--primary);
  width: 80px;
}

.resize-handle:active .resize-handle-bar {
  background: var(--primary-hover);
}

/* ==========================================
   Timeline Section
   ========================================== */

.timeline-section {
  grid-column: 1;
  background: white;
  border-top: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  box-shadow: 0 -4px 6px -1px rgba(0, 0, 0, 0.05);
  animation: slideInUp 0.4s cubic-bezier(0.16, 1, 0.3, 1);
  height: 450px;
  min-height: 300px;
  max-height: calc(100vh - 250px);
  width: 100%;
  max-width: 100%;
  overflow: hidden;
}

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

.timeline-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--spacing-md) var(--spacing-lg);
  background: linear-gradient(135deg, #FAFAFA, #FFFFFF);
  border-bottom: 1px solid var(--border);
}

.timeline-controls {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
}

.play-btn {
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, var(--secondary), var(--secondary-hover));
  color: white;
  border: none;
  border-radius: 50%;
  font-size: 1.25rem;
  cursor: pointer;
  transition: all var(--transition-normal);
  box-shadow: var(--shadow-md);
}

.play-btn:hover {
  transform: scale(1.1);
  box-shadow: var(--shadow-lg);
}

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

.timeline-info {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  font-size: 0.875rem;
  color: var(--text-secondary);
}

.timeline-info i {
  color: var(--primary);
}

.current-date {
  font-weight: 600;
  color: var(--text-primary);
}

.timeline-stats {
  display: flex;
  gap: var(--spacing-lg);
}

.stat-item {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-sm) var(--spacing-md);
  background: var(--bg-primary);
  border-radius: var(--radius-md);
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.stat-item i {
  color: var(--primary);
}

.stat-item span {
  color: var(--primary);
  font-weight: 700;
}

.btn-delete-all {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-sm) var(--spacing-md);
  background: var(--bg-primary);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.2s ease;
}

.btn-delete-all:hover {
  background: #ef4444;
  border-color: #dc2626;
  color: white;
}

.btn-delete-all i {
  font-size: 0.875rem;
}

.timeline-body {
  flex: 1;
  overflow-y: auto;
  padding: var(--spacing-md);
  background: var(--bg-primary);
}

/* ==========================================
   Timeline Rows & Bars
   ========================================== */

.timeline-row {
  position: relative;
  height: 48px;
  margin-bottom: var(--spacing-sm);
  background: white;
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
  animation: slideInRight 0.3s ease;
  transition: all var(--transition-normal);
}

@keyframes slideInRight {
  from {
    transform: translateX(-20px);
    opacity: 0;
  }
  to {
    transform: translateX(0);
    opacity: 1;
  }
}

.timeline-row:hover {
  box-shadow: var(--shadow-md);
  transform: translateX(4px);
}

.timeline-bar {
  position: absolute;
  height: 100%;
  border-radius: var(--radius-md);
  cursor: pointer;
  display: flex;
  align-items: center;
  padding: 0 var(--spacing-md);
  font-size: 0.875rem;
  font-weight: 600;
  color: white;
  transition: all var(--transition-normal);
  overflow: hidden;
  box-shadow: inset 0 1px 2px rgba(255, 255, 255, 0.2);
}

.timeline-bar::before {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.3), transparent);
  transition: left var(--transition-slow);
}

.timeline-bar:hover::before {
  left: 100%;
}

.timeline-bar:hover {
  transform: scale(1.02);
  filter: brightness(1.15);
  box-shadow: var(--shadow-lg);
}

.timeline-bar:active {
  transform: scale(0.98);
}

/* Build and Demolish colors */
.timeline-bar[data-type="Build"] {
  background: linear-gradient(135deg, #3B82F6, #2563EB);
}

.timeline-bar[data-type="Demolish"] {
  background: linear-gradient(135deg, #EF4444, #DC2626);
}

/* ==========================================
   Notification Toast
   ========================================== */

#overlay {
  position: fixed;
  top: 90px;
  right: 20px;
  background: white;
  color: var(--text-primary);
  padding: 1rem 1.5rem;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-xl);
  border-left: 4px solid var(--secondary);
  z-index: 9998;
  display: none;
  animation: slideInFromRight 0.3s ease;
  font-size: 0.875rem;
  font-weight: 500;
}

@keyframes slideInFromRight {
  from {
    transform: translateX(400px);
    opacity: 0;
  }
  to {
    transform: translateX(0);
    opacity: 1;
  }
}

/* ==========================================
   Scrollbar Styling
   ========================================== */

::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}

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

::-webkit-scrollbar-thumb {
  background: var(--border);
  border-radius: 999px;
}

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

/* ==========================================
   View Controls & Toggle
   ========================================== */

.view-controls {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
}

.view-toggle {
  display: flex;
  background: var(--bg-primary);
  border-radius: var(--radius-lg);
  padding: 4px;
  gap: 4px;
}

.view-btn {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  padding: 0.5rem 1rem;
  background: transparent;
  border: none;
  border-radius: var(--radius-md);
  font-family: 'Inter', sans-serif;
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition-normal);
}

.view-btn:hover {
  color: var(--primary);
  background: rgba(79, 70, 229, 0.1);
}

.view-btn.active {
  background: white;
  color: var(--primary);
  box-shadow: var(--shadow-sm);
}

.view-btn i {
  font-size: 1rem;
}

.export-btn {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  padding: 0.5rem 1rem;
  background: linear-gradient(135deg, #10B981, #059669);
  color: white;
  border: none;
  border-radius: var(--radius-lg);
  font-family: 'Inter', sans-serif;
  font-size: 0.875rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-normal);
  box-shadow: var(--shadow-md);
}

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

.export-btn:active {
  transform: translateY(0);
}

.export-btn i {
  font-size: 1rem;
}

.export-btn .fa-chevron-down {
  font-size: 0.75rem;
  margin-left: var(--spacing-xs);
  transition: transform var(--transition-normal);
}

.export-dropdown {
  position: relative;
}

.export-dropdown.active .fa-chevron-down {
  transform: rotate(180deg);
}

.export-menu {
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  min-width: 280px;
  background: white;
  border-radius: var(--radius-lg);
  box-shadow: 0 10px 40px rgba(0, 0, 0, 0.15);
  border: 1px solid var(--border);
  padding: var(--spacing-sm);
  opacity: 0;
  visibility: hidden;
  transform: translateY(-10px);
  transition: all var(--transition-normal);
  z-index: 1000;
}

.export-dropdown.active .export-menu {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.export-menu-item {
  width: 100%;
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  padding: var(--spacing-md);
  background: transparent;
  border: none;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition-normal);
  text-align: left;
}

.export-menu-item:hover {
  background: var(--bg-primary);
}

.export-menu-item i {
  font-size: 1.25rem;
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-md);
  flex-shrink: 0;
}

.export-menu-item:first-child i {
  color: #10B981;
  background: #D1FAE5;
}

.export-menu-item:last-child i {
  color: #8B5CF6;
  background: #EDE9FE;
}

.export-menu-text {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.export-menu-title {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-primary);
}

.export-menu-desc {
  font-size: 0.75rem;
  color: var(--text-secondary);
}

.export-menu-item:hover .export-menu-title {
  color: var(--primary);
}

/* Recording indicator */
.recording-indicator {
  position: fixed;
  top: 90px;
  left: 50%;
  transform: translateX(-50%);
  background: linear-gradient(135deg, #EF4444, #DC2626);
  color: white;
  padding: var(--spacing-md) var(--spacing-xl);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-xl);
  display: none;
  align-items: center;
  gap: var(--spacing-md);
  z-index: 9999;
  animation: slideInFromTop 0.3s ease;
}

@keyframes slideInFromTop {
  from {
    transform: translateX(-50%) translateY(-100px);
    opacity: 0;
  }
  to {
    transform: translateX(-50%) translateY(0);
    opacity: 1;
  }
}

.recording-indicator.active {
  display: flex;
}

.recording-dot {
  width: 12px;
  height: 12px;
  background: white;
  border-radius: 50%;
  animation: pulse-dot 1.5s ease-in-out infinite;
}

@keyframes pulse-dot {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.5; transform: scale(0.8); }
}

.recording-text {
  font-weight: 600;
  font-size: 0.875rem;
}

/* ==========================================
   View Containers
   ========================================== */

.view-container {
  display: none;
  opacity: 0;
  transition: opacity var(--transition-normal);
}

.view-container.active {
  display: block;
  opacity: 1;
  animation: fadeIn var(--transition-normal);
}

/* ==========================================
   Gantt Chart Styles
   ========================================== */

.gantt-container {
  display: flex;
  flex-direction: column;
  height: 100%;
  overflow: hidden;
}

.gantt-header {
  display: flex;
  border-bottom: 2px solid var(--border);
  background: white;
  position: sticky;
  top: 0;
  z-index: 10;
  width: 100%;
  max-width: 100%;
  overflow: hidden;
}

.gantt-fixed-columns {
  display: grid;
  grid-template-columns: 70px 250px 65px 65px 65px 90px 90px 75px 100px;
  flex-shrink: 0;
  border-right: 2px solid var(--border);
  overflow-x: auto;
  overflow-y: hidden;
  min-width: 870px;
  background: #F8F9FA;
}

/* Hide scrollbar for header fixed columns */
.gantt-fixed-columns::-webkit-scrollbar {
  display: none;
}
.gantt-fixed-columns {
  -ms-overflow-style: none;
  scrollbar-width: none;
}

.gantt-scrollable-timeline {
  flex: 1;
  overflow-x: auto;
  overflow-y: hidden;
}

/* Hide scrollbar for header timeline */
.gantt-scrollable-timeline::-webkit-scrollbar {
  display: none;
}
.gantt-scrollable-timeline {
  -ms-overflow-style: none;
  scrollbar-width: none;
}

.gantt-columns-header {
  padding: 8px 6px;
  font-weight: 600;
  font-size: 0.75rem;
  color: #1F2937;
  border-right: 1px solid #D1D5DB;
  border-bottom: 1px solid #D1D5DB;
  background: #E5E7EB;
  display: flex;
  align-items: center;
  justify-content: center;
  text-transform: uppercase;
  letter-spacing: 0.025em;
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
}

.gantt-timeline-header {
  display: flex;
  background: linear-gradient(135deg, #F9FAFB, #FFFFFF);
  min-height: 60px;
}

.gantt-date-column {
  min-width: 80px;
  padding: var(--spacing-md);
  border-right: 1px solid var(--border);
  text-align: center;
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.gantt-date-column.weekend {
  background: rgba(239, 68, 68, 0.05);
}

.gantt-body-wrapper {
  flex: 1;
  display: flex;
  overflow: hidden;
  background: var(--bg-primary);
  width: 100%;
  max-width: 100%;
}

.gantt-body-fixed {
  display: flex;
  flex-direction: column;
  flex-shrink: 0;
  min-width: 870px; /* 70 + 250 + 65 + 65 + 65 + 90 + 90 + 75 + 100 */
  border-right: 2px solid var(--border);
  overflow-x: auto;
  overflow-y: hidden;
  background: #FFFFFF;
}

.gantt-body-scrollable {
  flex: 1;
  overflow-x: auto;
  overflow-y: auto;
}

.gantt-body {
  position: relative;
  min-height: 100%;
}

.gantt-dependency-svg {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
  z-index: 1;
  overflow: visible;
}

.gantt-dependency-line {
  fill: none;
  stroke: var(--primary);
  stroke-width: 2;
  marker-end: url(#arrowhead-regular);
  transition: all 0.2s ease;
  cursor: pointer;
  pointer-events: stroke;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.gantt-dependency-line:hover {
  stroke-width: 3;
  opacity: 1 !important;
  filter: drop-shadow(0 0 3px currentColor);
}

.gantt-dependency-line.critical {
  stroke: var(--danger);
  stroke-width: 3;
}

.gantt-dependency-line.critical:hover {
  stroke-width: 4;
  filter: drop-shadow(0 0 5px #DC2626);
}

.gantt-bar.critical {
  background: linear-gradient(135deg, #DC2626, #991B1B) !important;
  box-shadow: 0 0 15px rgba(220, 38, 38, 0.5);
  border: 2px solid #7F1D1D;
}

.gantt-row-fixed {
  display: grid;
  grid-template-columns: 70px 250px 65px 65px 65px 90px 90px 75px 100px;
  border-bottom: 1px solid #E5E7EB;
  height: 28px;
  background: white;
  transition: all var(--transition-normal);
}

.gantt-row-fixed:nth-child(even) {
  background: #F9FAFB;
}

.gantt-row-fixed:hover,
.gantt-row-timeline:hover {
  background: #EFF6FF !important;
}

.gantt-row-timeline {
  border-bottom: 1px solid #E5E7EB;
  height: 28px;
  background: white;
  transition: all var(--transition-normal);
  position: relative;
}

.gantt-row-timeline:nth-child(even) {
  background: #F9FAFB;
}

.gantt-row-cell {
  padding: 4px 6px;
  border-right: 1px solid #E5E7EB;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.7rem;
  color: #374151;
  text-align: center;
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.gantt-task-name {
  padding: var(--spacing-md);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  gap: var(--spacing-xs);
  justify-content: center;
}

.gantt-task-name .task-title {
  font-weight: 600;
  font-size: 0.875rem;
  color: var(--text-primary);
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
}

.gantt-task-name .task-meta {
  font-size: 0.75rem;
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
}

.gantt-task-name .task-type-badge {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 2px 8px;
  border-radius: 999px;
  font-size: 0.7rem;
  font-weight: 600;
}

.gantt-task-name .task-type-badge.build {
  background: #DBEAFE;
  color: #1E40AF;
}

.gantt-task-name .task-type-badge.demolish {
  background: #FEE2E2;
  color: #991B1B;
}

.gantt-timeline {
  position: relative;
  display: flex;
  width: 100%;
  height: 100%;
}

.gantt-timeline-grid {
  display: flex;
  position: relative;
  height: 100%;
  min-width: fit-content;
}

.gantt-timeline-cell {
  width: 80px;
  height: 28px;
  flex-shrink: 0;
  border-right: 1px solid #E5E7EB;
  position: relative;
  background: white;
}

.gantt-timeline-cell.weekend {
  background: #F3F4F6;
}

.gantt-bar-container {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  padding: 4px 0;
  pointer-events: none;
  z-index: 2;
}

.gantt-bar {
  position: absolute;
  height: 20px;
  border-radius: 2px;
  cursor: pointer;
  display: flex;
  align-items: center;
  padding: 0 4px;
  font-size: 0.65rem;
  font-weight: 500;
  color: white;
  transition: all var(--transition-normal);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.15);
  overflow: visible;
  pointer-events: auto;
  border: 1px solid rgba(0, 0, 0, 0.1);
}

.gantt-bar-progress {
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.15);
  border-right: 2px solid rgba(0, 0, 0, 0.3);
  pointer-events: none;
}

.gantt-bar::before {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.3), transparent);
  transition: left var(--transition-slow);
}

.gantt-bar:hover::before {
  left: 100%;
}

.gantt-bar:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
  z-index: 5;
}

.gantt-bar.build {
  background: #3B82F6;
}

.gantt-bar.demolish {
  background: #F59E0B;
}

.gantt-bar.critical {
  background: #DC2626 !important;
  border-color: #991B1B !important;
}

.gantt-bar-label {
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  z-index: 1;
}

/* Empty state for gantt */
.gantt-empty {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  height: 100%;
  color: var(--text-secondary);
  gap: var(--spacing-md);
}

.gantt-empty i {
  font-size: 3rem;
  color: var(--border);
}

.gantt-empty p {
  font-size: 0.875rem;
}

/* Today marker line */
.gantt-today-marker {
  position: absolute;
  top: 0;
  bottom: 0;
  width: 2px;
  background: #EF4444;
  z-index: 5;
  pointer-events: none;
}

.gantt-today-label {
  position: absolute;
  top: -25px;
  left: 50%;
  transform: translateX(-50%);
  background: #EF4444;
  color: white;
  padding: 2px 8px;
  border-radius: 4px;
  font-size: 0.7rem;
  font-weight: 600;
  white-space: nowrap;
}

/* Playback position line */
.gantt-playback-marker {
  position: absolute;
  top: 0;
  bottom: 0;
  width: 3px;
  background: #10B981;
  z-index: 6;
  pointer-events: none;
  box-shadow: 0 0 8px rgba(16, 185, 129, 0.5);
  transition: left 0.3s ease-out;
}

.gantt-playback-label {
  position: absolute;
  top: -25px;
  left: 50%;
  transform: translateX(-50%);
  background: #10B981;
  color: white;
  padding: 2px 8px;
  border-radius: 4px;
  font-size: 0.7rem;
  font-weight: 600;
  white-space: nowrap;
}

/* ==========================================
   Responsive Design
   ========================================== */

@media (max-width: 768px) {
  .modern-header {
    padding: 0 var(--spacing-md);
  }

  .floating-add-btn {
    bottom: 20px;
    right: 20px;
    padding: 0.875rem 1.25rem;
    font-size: 0.875rem;
  }

  .modal-container {
    width: 95%;
  }

  .form-row {
    grid-template-columns: 1fr;
  }
}

/* ==========================================
   Accessibility
   ========================================== */

button:focus-visible,
input:focus-visible,
select:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}