/* CSS Reset & Base */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --primary: #107c41;
  --primary-hover: #0b5c30;
  --primary-light: #e8f5e9;
  --secondary: #4b5563;
  --secondary-hover: #374151;
  --bg-main: #f8fafc;
  --bg-surface: #ffffff;
  --border-color: #e2e8f0;
  --border-grid: #d1d5db;
  --text-main: #1e293b;
  --text-muted: #64748b;
  --text-light: #94a3b8;
  --grid-header-bg: #f3f4f6;
  --grid-header-text: #4b5563;
  --danger: #ef4444;
  --danger-light: #fef2f2;
  --success: #10b981;
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
  background-color: var(--bg-main);
  color: var(--text-main);
  line-height: 1.5;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Header */
.app-header {
  background: var(--bg-surface);
  border-bottom: 1px solid var(--border-color);
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: var(--shadow-sm);
}

.header-container {
  max-width: 1400px;
  margin: 0 auto;
  padding: 0.75rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.brand-group {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  cursor: pointer;
  user-select: none;
}

.brand-icon {
  background: var(--primary);
  color: #fff;
  width: 38px;
  height: 38px;
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 2px 4px rgba(16, 124, 65, 0.2);
}

.brand-text h1 {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text-main);
  letter-spacing: -0.01em;
}

.brand-subtitle {
  font-size: 0.75rem;
  color: var(--text-muted);
}

.active-file-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  background: var(--primary-light);
  color: var(--primary);
  font-weight: 600;
  font-size: 0.85rem;
  padding: 0.35rem 0.85rem;
  border-radius: 9999px;
  border: 1px solid rgba(16, 124, 65, 0.2);
  max-width: 350px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  font-size: 0.875rem;
  font-weight: 500;
  padding: 0.5rem 1rem;
  border-radius: 6px;
  border: 1px solid transparent;
  cursor: pointer;
  transition: all 0.15s ease-in-out;
  text-decoration: none;
  white-space: nowrap;
}

.btn-sm {
  padding: 0.35rem 0.75rem;
  font-size: 0.8125rem;
}

.btn-primary {
  background: var(--primary);
  color: #fff;
}

.btn-primary:hover {
  background: var(--primary-hover);
  box-shadow: 0 2px 4px rgba(16, 124, 65, 0.25);
}

.btn-secondary {
  background: var(--bg-surface);
  color: var(--text-main);
  border-color: var(--border-color);
}

.btn-secondary:hover {
  background: #f1f5f9;
  border-color: #cbd5e1;
}

.btn-outline {
  background: transparent;
  color: var(--secondary);
  border-color: var(--border-color);
}

.btn-outline:hover {
  background: #f1f5f9;
  color: var(--text-main);
}

/* Notification Bar */
.notification-bar {
  background: var(--danger-light);
  color: var(--danger);
  border-bottom: 1px solid #fecaca;
  padding: 0.75rem 1.5rem;
  animation: slideDown 0.2s ease-out;
}

.notification-bar.success {
  background: #ecfdf5;
  color: #065f46;
  border-bottom-color: #a7f3d0;
}

.notification-content {
  max-width: 1400px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.875rem;
  font-weight: 500;
}

.notification-close {
  background: none;
  border: none;
  font-size: 1.25rem;
  line-height: 1;
  color: inherit;
  cursor: pointer;
  padding: 0 0.25rem;
}

/* Main Content */
.main-content {
  flex: 1;
  display: flex;
  flex-direction: column;
}

.view-panel {
  display: none;
  flex: 1;
}

.view-panel.active {
  display: flex;
  flex-direction: column;
}

/* =========================================
   DASHBOARD VIEW
========================================= */
.dashboard-container {
  max-width: 1200px;
  width: 100%;
  margin: 0 auto;
  padding: 2rem 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

.card {
  background: var(--bg-surface);
  border-radius: 12px;
  border: 1px solid var(--border-color);
  box-shadow: var(--shadow-sm);
  overflow: hidden;
}

/* Upload Card & Dropzone */
.upload-card {
  transition: border-color 0.2s, box-shadow 0.2s;
}

.upload-dropzone {
  position: relative;
  padding: 2.5rem 1.5rem;
  border: 2px dashed #cbd5e1;
  border-radius: 12px;
  margin: 0.5rem;
  text-align: center;
  cursor: pointer;
  transition: all 0.2s ease;
  background: #fafbfc;
}

.upload-dropzone:hover, .upload-dropzone.drag-over {
  border-color: var(--primary);
  background: #f0fdf4;
}

.file-input-hidden {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  opacity: 0;
  cursor: pointer;
}

.upload-icon-circle {
  width: 64px;
  height: 64px;
  border-radius: 50%;
  background: var(--primary-light);
  color: var(--primary);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 1rem;
}

.dropzone-title {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--text-main);
  margin-bottom: 0.25rem;
}

.dropzone-text {
  font-size: 0.9375rem;
  color: var(--text-muted);
  margin-bottom: 0.75rem;
}

.browse-link {
  color: var(--primary);
  font-weight: 600;
  text-decoration: underline;
}

.file-types-hint {
  display: inline-block;
  font-size: 0.8125rem;
  color: var(--text-light);
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  padding: 0.25rem 0.65rem;
  border-radius: 4px;
}

.upload-progress-overlay {
  position: absolute;
  inset: 0;
  background: rgba(255, 255, 255, 0.95);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0.75rem;
  border-radius: 10px;
  font-weight: 500;
  color: var(--text-main);
}

/* Files Section */
.files-section {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.section-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.section-title {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-main);
}

.section-subtitle {
  font-size: 0.875rem;
  color: var(--text-muted);
}

.badge {
  background: #f1f5f9;
  color: var(--text-muted);
  font-size: 0.8125rem;
  font-weight: 600;
  padding: 0.25rem 0.65rem;
  border-radius: 9999px;
  border: 1px solid var(--border-color);
}

.empty-state {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 3rem 1.5rem;
  text-align: center;
  color: var(--text-muted);
}

.empty-icon {
  margin-bottom: 1rem;
  color: var(--text-light);
}

.empty-state h3 {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text-main);
  margin-bottom: 0.25rem;
}

.files-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 1rem;
}

/* File Card */
.file-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: 10px;
  padding: 1.25rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  cursor: pointer;
  transition: all 0.15s ease-in-out;
  box-shadow: var(--shadow-sm);
  position: relative;
}

.file-card:hover {
  transform: translateY(-2px);
  border-color: #93c5fd;
  box-shadow: var(--shadow-md);
}

.file-card-main {
  display: flex;
  gap: 1rem;
  align-items: flex-start;
  margin-bottom: 1rem;
}

.file-badge-icon {
  background: #f0fdf4;
  color: var(--primary);
  width: 44px;
  height: 44px;
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  border: 1px solid #bbf7d0;
}

.file-details {
  overflow: hidden;
}

.file-card-title {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-main);
  word-break: break-all;
  margin-bottom: 0.25rem;
}

.file-meta-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  font-size: 0.775rem;
  color: var(--text-muted);
}

.file-meta-item {
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
}

.file-card-actions {
  display: flex;
  gap: 0.5rem;
  border-top: 1px solid #f1f5f9;
  padding-top: 0.75rem;
}

.file-card-actions .btn {
  flex: 1;
}

/* =========================================
   SPREADSHEET VIEWER VIEW
========================================= */
.spreadsheet-container {
  display: flex;
  flex-direction: column;
  height: calc(100vh - 61px);
  background: var(--bg-surface);
  overflow: hidden;
}

.spreadsheet-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.5rem 1rem;
  border-bottom: 1px solid var(--border-color);
  background: #ffffff;
  flex-shrink: 0;
}

.toolbar-left {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  overflow: hidden;
}

.toolbar-title {
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text-main);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  max-width: 400px;
}

.sheet-stats-badge {
  font-size: 0.75rem;
  background: #f1f5f9;
  color: var(--text-muted);
  padding: 0.2rem 0.5rem;
  border-radius: 4px;
  white-space: nowrap;
  border: 1px solid var(--border-color);
}

/* Worksheet Tabs (Google Sheets style) */
.sheet-tabs-container {
  display: flex;
  align-items: center;
  background: #f3f4f6;
  border-bottom: 1px solid var(--border-grid);
  padding: 0 0.5rem;
  gap: 0.5rem;
  flex-shrink: 0;
  overflow-x: auto;
}

.sheet-tabs-label {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding-left: 0.5rem;
  white-space: nowrap;
}

.sheet-tabs-list {
  display: flex;
  gap: 0.25rem;
  overflow-x: auto;
  scrollbar-width: thin;
}

.sheet-tab {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.45rem 1rem;
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--text-muted);
  background: #e5e7eb;
  border: 1px solid var(--border-grid);
  border-bottom: none;
  border-top-left-radius: 6px;
  border-top-right-radius: 6px;
  cursor: pointer;
  white-space: nowrap;
  transition: all 0.1s ease;
  user-select: none;
}

.sheet-tab:hover {
  background: #f9fafb;
  color: var(--text-main);
}

.sheet-tab.active {
  background: #ffffff;
  color: var(--primary);
  font-weight: 600;
  border-top: 3px solid var(--primary);
  border-bottom: 1px solid #ffffff;
  margin-bottom: -1px;
}

/* Grid Viewport */
.grid-viewport {
  flex: 1;
  overflow: auto;
  position: relative;
  background: #ffffff;
}

.sheet-table {
  border-collapse: separate;
  border-spacing: 0;
  width: max-content;
  min-width: 100%;
  font-size: 0.8125rem;
  color: var(--text-main);
  table-layout: fixed;
}

/* Google Sheets Header Rows */
.sheet-table thead tr th {
  position: sticky;
  top: 0;
  background: var(--grid-header-bg);
  color: var(--grid-header-text);
  font-weight: 600;
  text-align: center;
  padding: 0.35rem 0.5rem;
  border-right: 1px solid var(--border-grid);
  border-bottom: 1px solid var(--border-grid);
  z-index: 20;
  user-select: none;
  min-width: 100px;
  max-width: 250px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

/* Corner Cell */
.sheet-table thead tr th.corner-cell {
  position: sticky;
  top: 0;
  left: 0;
  z-index: 30;
  background: #e5e7eb;
  width: 48px;
  min-width: 48px;
  max-width: 48px;
  border-right: 1px solid var(--border-grid);
  border-bottom: 1px solid var(--border-grid);
}

/* Row Numbers Column */
.sheet-table tbody tr th.row-header {
  position: sticky;
  left: 0;
  z-index: 10;
  background: var(--grid-header-bg);
  color: var(--grid-header-text);
  font-weight: 500;
  text-align: center;
  padding: 0.35rem 0.5rem;
  width: 48px;
  min-width: 48px;
  max-width: 48px;
  border-right: 1px solid var(--border-grid);
  border-bottom: 1px solid var(--border-grid);
  user-select: none;
}

/* Data Cells */
.sheet-table tbody tr td {
  padding: 0.35rem 0.65rem;
  border-right: 1px solid var(--border-grid);
  border-bottom: 1px solid var(--border-grid);
  white-space: pre-wrap;
  word-break: break-word;
  max-width: 350px;
  min-width: 100px;
  line-height: 1.35;
  background: #ffffff;
}

/* Editable Data Cells */
.sheet-table tbody tr td.editable-cell {
  cursor: cell;
  outline: none;
  transition: background-color 0.1s;
}

.sheet-table tbody tr td.editable-cell:hover {
  background-color: #eff6ff;
}

.sheet-table tbody tr td.editable-cell:focus {
  background-color: #ffffff !important;
  outline: 2px solid #2563eb !important;
  box-shadow: inset 0 0 0 1px #2563eb, 0 2px 4px rgba(37, 99, 235, 0.15);
  z-index: 15;
  position: relative;
}

.sheet-table tbody tr td.cell-modified {
  background-color: #fefce8;
}

.sheet-table tbody tr:hover td {
  background-color: #f8fafc;
}

.sheet-table tbody tr:hover td.cell-modified {
  background-color: #fef08a;
}

.sheet-table tbody tr:hover th.row-header {
  background-color: #e5e7eb;
}

.btn-success {
  background: #15803d;
  color: #fff;
  border-color: #15803d;
}

.btn-success:hover {
  background: #166534;
  box-shadow: 0 2px 4px rgba(22, 101, 52, 0.25);
}

.badge-unsaved {
  background: #fef3c7;
  color: #b45309;
  border: 1px solid #fde68a;
  font-size: 0.75rem;
  font-weight: 600;
  padding: 0.25rem 0.5rem;
  border-radius: 9999px;
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
}

/* Loading & Empty placeholders */
.grid-loading-overlay {
  position: absolute;
  inset: 0;
  background: rgba(255, 255, 255, 0.85);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0.75rem;
  z-index: 50;
  font-size: 0.875rem;
  color: var(--text-muted);
}

.sheet-empty-placeholder {
  padding: 4rem 1.5rem;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.95rem;
}

.spreadsheet-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.4rem 1rem;
  background: #f8fafc;
  border-top: 1px solid var(--border-color);
  font-size: 0.75rem;
  color: var(--text-muted);
  flex-shrink: 0;
}

.footer-tip {
  font-style: italic;
}

/* Spinner */
.spinner {
  width: 28px;
  height: 28px;
  border: 3px solid rgba(16, 124, 65, 0.2);
  border-top-color: var(--primary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

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

@keyframes slideDown {
  from { opacity: 0; transform: translateY(-8px); }
  to { opacity: 1; transform: translateY(0); }
}

/* Responsive adjustments */
@media (max-width: 640px) {
  .header-container {
    padding: 0.5rem 1rem;
  }
  .brand-text h1 {
    font-size: 1rem;
  }
  .active-file-badge {
    display: none !important;
  }
  .files-grid {
    grid-template-columns: 1fr;
  }
}