body {
          font-family: 'Inter', sans-serif;
          background-color: #ffffff;
          color: #111827;
          position: fixed;
          width: 100%;
          height: 100%;
          overscroll-behavior: none;
      }

      #app {
          background-image: radial-gradient(#e5e7eb 1px, transparent 1px);
          background-size: 20px 20px;
      }

      #whiteboard {
          touch-action: none;
          -webkit-touch-callout: none;
      }

      .neo-toolbar {
          border: 3px solid #1f2937;
          box-shadow: 8px 8px 0 rgba(0, 0, 0, 0.15);
          background: rgba(255, 255, 255, 0.98);
          backdrop-filter: blur(8px);
      }

      .tool-btn {
          transition: all 0.12s ease;
          border-radius: 1rem;
          font-size: 1.25rem;
          border: 2px solid #334155;
          background-color: white;
          color: #1e293b;
          min-width: 3rem;
          height: 3rem;
          display: inline-flex;
          align-items: center;
          justify-content: center;
          box-shadow: 3px 3px 0 #94a3b8;
          flex-shrink: 0;
      }

      @media (min-width: 768px) {
          .tool-btn {
              min-width: 3.5rem;
              height: 3.5rem;
              font-size: 1.4rem;
          }
      }

      .tool-btn:active {
          transform: translate(2px, 2px);
          box-shadow: 1px 1px 0 #94a3b8;
      }

      .tool-btn[aria-pressed="true"] {
          background-color: #dbeafe;
          border-color: #2563eb;
          box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.3), 3px 3px 0 #3b82f6;
          transform: scale(1.02);
      }

      .color-btn {
          transition: all 0.1s ease;
          border-width: 3px;
          width: 2.25rem;
          height: 2.25rem;
          border-radius: 50%;
          border-color: #1e293b;
          box-shadow: 3px 3px 0 #94a3b8;
          flex-shrink: 0;
      }

      @media (min-width: 768px) {
          .color-btn {
              width: 2.8rem;
              height: 2.8rem;
          }
      }

      .color-btn[aria-current="true"] {
          transform: scale(1.15);
          border-color: #2563eb !important;
          box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.3), 3px 3px 0 #2563eb;
      }

      #size-range {
          height: 0.75rem;
          -webkit-appearance: none;
          appearance: none;
          background: #e2e8f0;
          border-radius: 999px;
          border: 2px solid #1e293b;
          outline: none;
      }

      #size-range::-webkit-slider-thumb {
          -webkit-appearance: none;
          appearance: none;
          width: 1.75rem;
          height: 1.75rem;
          background: #2563eb;
          border-radius: 50%;
          border: 3px solid white;
          box-shadow: 0 2px 8px rgba(0, 0, 0, 0.2), 0 0 0 2px #1e293b;
          cursor: pointer;
      }

      #size-range::-moz-range-thumb {
          width: 1.75rem;
          height: 1.75rem;
          background: #2563eb;
          border-radius: 50%;
          border: 3px solid white;
          box-shadow: 0 2px 8px rgba(0, 0, 0, 0.2), 0 0 0 2px #1e293b;
          cursor: pointer;
      }

      .modal-card {
          border: 3px solid #1e293b;
          box-shadow: 12px 12px 0 rgba(0, 0, 0, 0.15);
          border-radius: 2rem;
          background: white;
      }

      .modal-btn {
          border-radius: 1.5rem;
          font-weight: 600;
          padding: 0.75rem 1.5rem;
          border: 2px solid #1e293b;
          transition: 0.1s ease;
          box-shadow: 4px 4px 0 #94a3b8;
      }

      .modal-btn-primary {
          background: #2563eb;
          color: white;
          border-color: #1e293b;
          box-shadow: 4px 4px 0 #0f172a;
      }

      .modal-btn-primary:active {
          transform: translate(2px, 2px);
          box-shadow: 2px 2px 0 #0f172a;
      }

      #qr-output canvas,
      #qr-output img,
      #qr-zoom-content canvas,
      #qr-zoom-content img {
          margin: 0 auto;
          max-width: 100%;
          height: auto;
      }

      .hide-scrollbar::-webkit-scrollbar {
          display: none;
      }

      .hide-scrollbar {
          -ms-overflow-style: none;
          scrollbar-width: none;
      }

      * {
          -webkit-tap-highlight-color: transparent;
      }