Ok, the easiest solution is what Moini and I both mentioned. If it's your webpage, meaning you wrote the code, you can set the size.....I forget which tags and elements are used for that. But you set the size you want, and only the part of the image which is inside that size will show.
If you don't have access to the code, it's possible there already is a size set. It's a very common way to write html. So you can try to upload and and see what happens.
If you've already tried that, and it doesn't work, then here's how to adjust the filter. Note that with as much overlap as you showed, it might not be possible to fix, but here's how you can try.
In the bottom section of the Filter Editor, click the tab "Filter General Settings" (someone should make that grammatically correct someday "general filter settings"!) Try adjusting both sets - Coordinates and Dimensions. But only adjust one at a time. Most likely, you'll need to adjust by the same amount....well they aren't labelled, but one is for x and one is for y (or width and height). Anyway, change them by the same values.
Also, make small changes at a time, until you can see and get a feel for what they are doing. Keep watching your image after each change. (edit the number in the field, and press Enter to put into effect) At first, just change by 0.10 at a time. Once you can see what it does, you can try larger changes.
If you could upload the SVG file, I could try it for you, if you don't feel comfortable with it. As I've said, with that much overlap....it might not be fixable. Hhmm....now that I think of it, I'm not sure if you should be seeing that much overlap for the Greyscale filter. Is there any chance you accidentally have another filter applied to it? You can find out by selecting and looking at the status bar. Or you would see it in the Filter Editor as well (in the top section, left column).
