How to use this PDF cropper:

1. Select a PDF file using the button above or by dragging and dropping
2. Adjust crop settings in the sidebar (margins, aspect ratio, etc.)
3. Drag on the PDF preview to select the area you want to keep
4. Click "Crop Selection" to apply to current page or "Crop All Pages" for entire document
5. Use page navigation to crop different pages individually
6. After cropping, click "Download Cropped Area" to save your selection