Align image and gallery on the right

I have a page - full width, no sidebar - on which I have a single photo aligned to the right of the text and a gallery of thumbnails below the text (default wordpress gallery, no plug-in). The width of the gallery is responsive and fills most of the width of the screen but for some reason the padding on the right is different to that of the individual picture, so that the gallery and the picture on the right don't align. How do I adjust the padding of the gallery on the right so that it aligns with the picture?