bower concat CSS problems - gruntjs

Question

Grunt novice here....what I am trying to do seems so simple, but I am at my wits end here. I am trying to concat the JS from a few separate bower components and then do the same with the CSS. Here is the relevant code from my grunt.file:
bower_concat: {
all: {
dest: 'builds/development/js/_bower.js',
cssDest: 'builds/development/css/_bower.css'
}
}
This is the last item in my config so does not need a comma after the final "}".
All the needed files are listed under "main" in their respective bower.json files. For example:
"main": [
"dist/owl.carousel.js",
"dist/assets/owl.carousel.css",
"dist/assets/owl.theme.css",
"dist/assets/owl.transitions.css"
],
I am positive these paths and file names are correct. The JS concats fine. The CSS does nothing. If I remove the "dest:..." line from my gruntfile (in an attempt to concat ONLY the CSS) terminal gives me the error ":Warning: You should specify "dest" and/or "cssDest" properties in your Gruntfile".
I clearly am specifying this. Help!

Answer 1

Finally got it to work with this:
bower_concat: {
all: {
dest: {
js: 'builds/development/js/_bower.js',
css: 'builds/development/css/_bower.css'
},
},
}
Essentially needed one more set of nested curly braces inside of "dest:". For the record you DO NOT need to specify mainFiles if they are designated in the bower_components json.

Answer 2

Ah, easy. You need to specify the component or library and then its mainFiles in your Gruntfile under grunt-bower-concat. Don't worry about messing with the individual components' files.
bower_concat: {
all: {
dest: 'builds/development/js/_bower.js',
cssDest: 'builds/development/css/_bower.css'
}
mainFiles: [
owlcarousel: [
"dist/owl.carousel.js",
"dist/assets/owl.carousel.css",
"dist/assets/owl.theme.css",
"dist/assets/owl.transitions.css"
],
],
}
FYI My current bower-concat for owlcarousel looks like this so double-check your bower_components folder tree structure.
bower_concat: {
all: {
dest: 'builds/development/js/_bower.js',
cssDest: 'builds/development/css/_bower.css'
}
mainFiles: [
owlcarousel: [
"owl-carousel/owl.carousel.js",
"owl-carousel/owl.carousel.css",
"owl-carousel/owl.theme.css",
"owl-carousel/owl.transitions.css"
], // (Version 1.3.2)
],
}