Feature request: Auto-resize thumbnails

Already done, this can be set on WP admin panel, Settings => UnPointZero Slider => Automatic CSS resizing.

BTW, images must be uploaded AFTER saving this settings. If you want to use already uploaded images, u’ve to regenerate thumbnails. Just download this https://www.ads-software.com/plugins/regenerate-thumbnails/ and on your WP admin panel Tools => Regenerate thumbnails.