@charset "UTF-8"; @import "import/test.less"; .start() { .test2 { color: red; } } .mix() { color: black; } .test1 { .mix(); } .start(); .mixin_import1(); .mixin_import2(); @debug: 1; & when (@debug = 1) { .test { color: red; & when (@debug = 1) { width: 2; } } }