diff --git a/src/styles/_mixins.scss b/src/styles/_mixins.scss
index 04347b3131..ae9e6082f5 100644
--- a/src/styles/_mixins.scss
+++ b/src/styles/_mixins.scss
@@ -1,4 +1,3 @@
-@import '../../node_modules/bootstrap/scss/functions.scss';
 @import '../../node_modules/bootstrap/scss/mixins.scss';
 
 @mixin word-wrap() {
diff --git a/webpack/helpers.ts b/webpack/helpers.ts
index 532b170bf3..43855f6c72 100644
--- a/webpack/helpers.ts
+++ b/webpack/helpers.ts
@@ -6,8 +6,8 @@ export const projectRoot = (relativePath) => {
 
 export const globalCSSImports = () => {
   return [
-    projectRoot('src/styles/_variables.scss'),
-    projectRoot('src/styles/_mixins.scss'),
+    projectRoot(path.join('src', 'styles', '_variables.scss')),
+    projectRoot(path.join('src', 'styles', '_mixins.scss')),
   ];
 };
 
diff --git a/webpack/webpack.common.ts b/webpack/webpack.common.ts
index 926241e0bb..07e55d89d4 100644
--- a/webpack/webpack.common.ts
+++ b/webpack/webpack.common.ts
@@ -17,7 +17,9 @@ export const copyWebpackOptions = {
       to: 'assets',
     },
     {
-      from: path.join(__dirname, '..', 'src', 'themes', '*', 'assets', '**', '*'),
+      // replace(/\\/g, '/') because glob patterns need forward slashes, even on windows:
+      // https://github.com/mrmlnc/fast-glob#how-to-write-patterns-on-windows
+      from: path.join(__dirname, '..', 'src', 'themes', '*', 'assets', '**', '*').replace(/\\/g, '/'),
       to: 'assets',
       noErrorOnMissing: true,
       transformPath(targetPath, absolutePath) {
@@ -77,7 +79,7 @@ export const commonExports = {
         test: /\.scss$/,
         exclude: [
           /node_modules/,
-          /(_exposed)?_variables.scss$|\/src\/themes\/[^/]+\/styles\/.+.scss$/
+          /(_exposed)?_variables.scss$|[\/|\\]src[\/|\\]themes[\/|\\].+?[\/|\\]styles[\/|\\].+\.scss$/
         ],
         use: [
           ...SCSS_LOADERS,
@@ -90,7 +92,7 @@ export const commonExports = {
         ]
       },
       {
-        test: /(_exposed)?_variables.scss$|\/src\/themes\/[^/]+\/styles\/.+.scss$/,
+        test: /(_exposed)?_variables.scss$|[\/|\\]src[\/|\\]themes[\/|\\].+?[\/|\\]styles[\/|\\].+\.scss$/,
         exclude: [/node_modules/],
         use: [
           ...SCSS_LOADERS,