Hello,
I can see that the "End" part is not lining up with the rest of the pagination. You can fix this by adding the following to the bottom of the Template.CSS file or Custom.CSS file.
.pagination ul > li > a, .pagination ul > li > span {padding: 4px 12px !important;}
In regards to the pagination looking the way it does on mobile unfortunately there isn't a way around that as this isn't a responsive theme. The clipping occurs because the element is too wide to fit the view port size of the device. There might be a setting under the Menu > Article options to disable Pagination and Pagination Results to offer more room here on smaller devices but I am not 100% sure on that. The only other option would be to disable pagination completely with CSS on smaller devices but this would make navigation tricky.
Regards,