[bugfix] gulp-less import (#2319)

build/build-style.js

@@ -1,3 +1,4 @@
+const path = require('path');
 const gulp = require('gulp');
 const less = require('gulp-less');
 const csso = require('gulp-csso');
@@ -7,7 +8,9 @@ const postcss = require('gulp-postcss');
 gulp.task('compile', () => (
   gulp
     .src(['../es/**/*.less', '../lib/**/*.less'])
-    .pipe(less())
+    .pipe(less({
+      paths: [path.resolve(__dirname, 'node_modules')]
+    }))
     .pipe(postcss())
     .pipe(csso())
     .pipe(gulp.dest(file => file.base.replace('.less', '.css')))