I have problems with the highlighted image because when displaying it on the home page it looks blurred, when I review the recommended size 480×280 in jpg and put it on it, it continues to cause problems. When entering the blog, and putting on the featured image, it looks sharp but in the previous box, no. Someone could help me? I have tried putting them in all the recommended sizes and including changing the format of the image.
Ones you set up new image sizes in WordPress admin according to theme recommended ones, you need to use Force Regenerate Thumbnail plugin to regenerate the new sizes for your already uploaded images. Once you activate the plugin you have to run the process of regenerating manually in Tools → Force Regenerate Thumbnails in your WordPress admin.