code: function(){
  		// Calculate block size for the image
  		// Use pixel values, or 100% for X axis where needed (repeat:x)
  		
  		this.blockWidth = (this.repeat==="x" && this['limit-repeat-x'] || "100%")
  								|| (this.align!="block" && "100%") || this.width;
  		this.blockHeight = (this.repeat=="y" && this['limit-repeat-y']) || this.height;
  		
  		// Block height can't be lower than image height
  		if(this.blockHeight<this.height) this.blockHeight=this.height;
  	}
docs: /* https://github.com/andris9/stylus-sprite/blob/master/stylus-sprite.js#L283