:root {
          --nexus-primary: #3b82f6;
          --nexus-secondary: #64748b;
          --nexus-success: #10b981;
          --nexus-warning: #f59e0b;
          --nexus-danger: #ef4444;
          --nexus-info: #06b6d4;
      }

      body {
          background: var(--dm-slate-50);
          min-height: 100vh;
          display: flex;
          flex-direction: column;
      }

      main {
          flex: 1;
          padding: 2rem 0;
      }

      /* App Layout */
      .app-container {
          max-width: 1200px;
          margin: 0 auto;
          padding: 0 1rem;
      }

      .app-header {
          display: flex;
          justify-content: space-between;
          align-items: center;
          margin-bottom: 2rem;
          flex-wrap: wrap;
          gap: 1rem;
      }

      .app-title {
          display: flex;
          align-items: center;
          gap: 0.75rem;
          font-size: 1.875rem;
          font-weight: 700;
          color: var(--dm-slate-900);
          margin: 0;
      }

      .app-status {
          display: flex;
          align-items: center;
          gap: 1rem;
          font-size: 0.875rem;
          color: var(--dm-slate-600);
      }

      .connection-status.online {
          color: var(--nexus-success);
      }

      .connection-status.offline {
          color: var(--nexus-warning);
      }

      .sync-status.has-pending {
          color: var(--nexus-warning);
      }

      /* Navigation Tabs */
      .tab-nav {
          display: flex;
          gap: 0.5rem;
          margin-bottom: 2rem;
          border-bottom: 2px solid var(--dm-slate-200);
      }

      .tab-nav button {
          padding: 0.75rem 1.5rem;
          background: none;
          border: none;
          border-bottom: 3px solid transparent;
          font-weight: 500;
          color: var(--dm-slate-600);
          cursor: pointer;
          transition: all 0.2s;
      }

      .tab-nav button:hover {
          color: var(--dm-slate-900);
          background: var(--dm-slate-100);
      }

      .tab-nav button.active {
          color: var(--nexus-primary);
          border-bottom-color: var(--nexus-primary);
          background: var(--dm-blue-50);
      }

      /* Toolbar */
      .toolbar {
          display: flex;
          justify-content: space-between;
          align-items: center;
          gap: 1rem;
          margin-bottom: 1.5rem;
          flex-wrap: wrap;
      }

      .toolbar-left {
          display: flex;
          align-items: center;
          gap: 1rem;
          flex: 1;
      }

      .toolbar-right {
          display: flex;
          align-items: center;
          gap: 0.5rem;
      }

      .search-group {
          position: relative;
          width: 100%;
          max-width: 400px;
      }

      .search-group .icon {
          position: absolute;
          left: 0.75rem;
          top: 50%;
          transform: translateY(-50%);
          color: var(--dm-slate-400);
          pointer-events: none;
      }

      .search-group input {
          padding-left: 2.25rem;
      }

      /* Content Areas */
      .tab-content {
          display: none;
      }

      .tab-content.active {
          display: block;
      }

      /* Contact Cards */
      .contact-card {
          display: flex;
          align-items: center;
          gap: 1rem;
          padding: 1rem;
          background: white;
          border: 1px solid var(--dm-slate-200);
          border-radius: 8px;
          margin-bottom: 0.75rem;
          transition: all 0.2s;
      }

      .contact-card:hover {
          border-color: var(--nexus-primary);
          box-shadow: 0 2px 8px rgba(59, 130, 246, 0.1);
      }

      .contact-avatar {
          width: 48px;
          height: 48px;
          background: var(--nexus-primary);
          color: white;
          border-radius: 50%;
          display: flex;
          align-items: center;
          justify-content: center;
          font-weight: 600;
          font-size: 1.125rem;
          flex-shrink: 0;
      }

      .contact-info {
          flex: 1;
          min-width: 0;
      }

      .contact-name {
          font-weight: 600;
          color: var(--dm-slate-900);
          margin-bottom: 0.25rem;
          display: flex;
          align-items: center;
          gap: 0.5rem;
      }

      .contact-name .favourite {
          color: var(--nexus-warning);
      }

      .contact-details {
          color: var(--dm-slate-600);
          font-size: 0.875rem;
      }

      .contact-email {
          margin-bottom: 0.125rem;
      }

      .contact-company, .contact-phone {
          margin-bottom: 0.125rem;
      }

      .contact-tags {
          margin-top: 0.5rem;
          display: flex;
          flex-wrap: wrap;
          gap: 0.25rem;
      }

      .tag {
          padding: 0.125rem 0.5rem;
          background: var(--dm-slate-100);
          color: var(--dm-slate-700);
          font-size: 0.75rem;
          border-radius: 12px;
      }

      .contact-actions {
          display: flex;
          gap: 0.5rem;
          flex-shrink: 0;
      }

      /* Group Cards */
      .group-card {
          display: flex;
          align-items: center;
          gap: 1rem;
          padding: 1rem;
          background: white;
          border: 1px solid var(--dm-slate-200);
          border-radius: 8px;
          margin-bottom: 0.75rem;
          transition: all 0.2s;
      }

      .group-card:hover {
          border-color: var(--nexus-primary);
          box-shadow: 0 2px 8px rgba(59, 130, 246, 0.1);
      }

      .group-color {
          width: 16px;
          height: 48px;
          border-radius: 8px;
          flex-shrink: 0;
      }

      .group-info {
          flex: 1;
          min-width: 0;
      }

      .group-name {
          font-weight: 600;
          color: var(--dm-slate-900);
          margin-bottom: 0.25rem;
      }

      .group-details {
          color: var(--dm-slate-600);
          font-size: 0.875rem;
          display: flex;
          gap: 1rem;
      }

      .group-description {
          color: var(--dm-slate-500);
          font-size: 0.875rem;
          margin-top: 0.25rem;
      }

      .group-actions {
          display: flex;
          gap: 0.5rem;
          flex-shrink: 0;
      }

      /* Card Styling - Rounded boxes with drop shadows */
      #contacts-table, #groups-table {
          background: white;
          border-radius: 12px;
          box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
          border: 1px solid var(--dm-slate-200);
          overflow: hidden;
          margin-bottom: 1.5rem;
          padding: 1.5rem;
      }

      /* Table specific styling to work with card */
      #contacts-table, #groups-table {
          border-collapse: separate;
          border-spacing: 0;
      }

      #contacts-table thead th, #groups-table thead th {
          background: var(--dm-slate-50);
          border-bottom: 1px solid var(--dm-slate-200);
          padding: 1rem;
          font-weight: 600;
          color: var(--dm-slate-700);
      }

      #contacts-table tbody td, #groups-table tbody td {
          padding: 1rem;
          border-bottom: 1px solid var(--dm-slate-100);
      }

      #contacts-table tbody tr:last-child td, #groups-table tbody tr:last-child td {
          border-bottom: none;
      }

      #contacts-table tbody tr:hover, #groups-table tbody tr:hover {
          background: var(--dm-slate-50);
      }

      /* Groups list card styling */
      #groups-list {
          padding: 1rem;
      }

      #groups-list:empty {
          padding: 0;
      }

      /* Empty States */
      .empty-state {
          text-align: center;
          padding: 3rem 1rem;
          color: var(--dm-slate-500);
      }

      .empty-state .icon {
          font-size: 3rem;
          color: var(--dm-slate-300);
          margin-bottom: 1rem;
      }

      .empty-state h3 {
          font-size: 1.25rem;
          color: var(--dm-slate-700);
          margin-bottom: 0.5rem;
      }

      .empty-state p {
          margin-bottom: 1.5rem;
      }

      /* Loading Overlay */
      .loading-overlay {
          position: fixed;
          top: 0;
          left: 0;
          width: 100%;
          height: 100%;
          background: rgba(255, 255, 255, 0.8);
          display: none;
          align-items: center;
          justify-content: center;
          z-index: 1000;
      }

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

      .loading-spinner {
          display: flex;
          align-items: center;
          gap: 1rem;
          padding: 1.5rem;
          background: white;
          border-radius: 8px;
          box-shadow: 0 10px 25px rgba(0, 0, 0, 0.1);
      }

      .spinner {
          width: 24px;
          height: 24px;
          border: 3px solid var(--dm-slate-200);
          border-radius: 50%;
          border-top-color: var(--nexus-primary);
          animation: spin 1s linear infinite;
      }

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

      .spinning {
          animation: spin 1s linear infinite;
      }

      /* Login Prompt */
      .login-prompt {
          text-align: center;
          padding: 3rem 1rem;
          max-width: 400px;
          margin: 2rem auto;
          background: white;
          border-radius: 12px;
          box-shadow: 0 4px 16px rgba(0, 0, 0, 0.1);
      }

      .login-prompt .icon {
          font-size: 3rem;
          color: var(--nexus-primary);
          margin-bottom: 1rem;
      }

      .login-prompt h2 {
          margin-bottom: 0.5rem;
          color: var(--dm-slate-900);
      }

      .login-prompt p {
          color: var(--dm-slate-600);
          margin-bottom: 2rem;
      }

      /* Responsive */
      @media (max-width: 768px) {
          .app-header {
              flex-direction: column;
              align-items: flex-start;
          }

          .toolbar {
              flex-direction: column;
              align-items: stretch;
          }

          .toolbar-left {
              flex-direction: column;
          }

          .search-group {
              max-width: none;
          }

          .contact-card, .group-card {
              flex-direction: column;
              align-items: flex-start;
              text-align: left;
          }

          .contact-actions, .group-actions {
              align-self: stretch;
              justify-content: center;
          }
      }