Enduro.js has spritesheet generation built-in.
Save all your sprites to assets/spriteicons. These sprites should be png and you also need to save a double sized sprite, with @2x added at the end of the name.
The spritesheet generation process will generate a .scss file that stores coordinates for each sprite. You have to include this file in your main.scss file. Use syntax below to include this file.
@import '../../_generated/_prebuilt/sprites';
You can access the sprites with a convenient mixin @include retina-sprite($<original_file_name>);
. This mixin will set the background image, its position and its size.
Credits to https://github.com/Ensighten/spritesmith, which enduro.js uses internally to provide support for retina sprites.