You would be better off changing that code to use the CSS classes in WordPress. Because WordPress finds each page using a database, you would need to use a plugin like the following:
You would then need to get the classes used by WordPress for their Next and Previous links and style them to have those images for the links. Looking at the CSS code you provided, you would have to change the classes .blog-pager-newer-link , .blog-pager-older-link, and the others for to use the WordPress classes.
Unfortunately, that will require you to know CSS code and how it works. You would be better off looking in the WordPress plugins to see if there is a version you like already set up.
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