Publication cover image does not scale

I’ve created a publication cover for my website. It’s a simple black background with the name of my site in custom font. There’s no issues displaying it on the site, but when I access the site on a different screen, or through mobile phone, most of the text is cutoff. The cover does not scale to whatever size the screen is. How do I fix this?

On a separate note, is there an optimal pixel size to upload images for the publication cover?

Does anyone have an answer in terms of making a publication cover scalable on mobile devices? On a normal laptop screen it looks fine, on mobile almost all the words are cut off. Is there anything i can add as code injection to make it scale appropriately so it can be seen on both devices?