build.gradle

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath group: 'com.google.closure-stylesheets', name: 'closure-stylesheets', version: '20160212'
    }
}

plugins {
    id 'java'
    id 'war'
}

group 'internal.example'
version '1.0-SNAPSHOT'

sourceCompatibility = 1.7

repositories {
    mavenCentral()
}

dependencies {
    testCompile group: 'junit', name: 'junit', version: '4.11'
}

task runCSS(type: JavaExec) {

    classpath = buildscript.configurations.classpath
    main = 'com.google.common.css.compiler.commandline.ClosureCommandLineCompiler'

    // arguments to pass to the application
    args = ['--pretty-print',
            '--output-file', 'dialog.css',
            '--output-renaming-map-format', 'CLOSURE_COMPILED',
            '--rename', 'CLOSURE',
            '--output-renaming-map', 'renaming_map.js',
            "$projectDir/src/custom/css/file1.css", "$projectDir/src/custom/css/file2.css"]
}