Incompatible units: 'rem' and 'px' - Bootstrap 4 and Laravel Mix : <p>I just installed a fresh Laravel 5.4, and bootstrap 4 alpha 6. Laravel mix wont compile SASS:
Here is one error:</p>

<pre><code>    Module build failed: ModuleBuildError: Module build failed: 
$input-height:                   (($font-size-base * $input-line-height) + ($input-padding-y * 2)) !default;
                                ^
      Incompatible units: 'rem' and 'px'.
      in /Volumes/HDD/nicolae/Dev/htdocs/test/node_modules/bootstrap/scss/_variables.scss (line 444, column 34)
    at runLoaders (/Volumes/HDD/nicolae/Dev/htdocs/test/node_modules/webpack/lib/NormalModule.js:192:19)
    at /Volumes/HDD/nicolae/Dev/htdocs/test/node_modules/loader-runner/lib/LoaderRunner.js:364:11
    at /Volumes/HDD/nicolae/Dev/htdocs/test/node_modules/loader-runner/lib/LoaderRunner.js:230:18
    at context.callback (/Volumes/HDD/nicolae/Dev/htdocs/test/node_modules/loader-runner/lib/LoaderRunner.js:111:13)
    at Object.asyncSassJobQueue.push [as callback] (/Volumes/HDD/nicolae/Dev/htdocs/test/node_modules/sass-loader/lib/loader.js:57:13)
    at Object.&lt;anonymous&gt; (/Volumes/HDD/nicolae/Dev/htdocs/test/node_modules/sass-loader/node_modules/async/dist/async.js:2262:31)
    at apply (/Volumes/HDD/nicolae/Dev/htdocs/test/node_modules/sass-loader/node_modules/async/dist/async.js:20:25)
    at Object.&lt;anonymous&gt; (/Volumes/HDD/nicolae/Dev/htdocs/test/node_modules/sass-loader/node_modules/async/dist/async.js:56:12)
    at Object.callback (/Volumes/HDD/nicolae/Dev/htdocs/test/node_modules/sass-loader/node_modules/async/dist/async.js:944:16)
    at options.error (/Volumes/HDD/nicolae/Dev/htdocs/test/node_modules/node-sass/lib/index.js:294:32)

 @ multi ./resources/assets/js/app.js ./resources/assets/sass/app.scss
</code></pre>

<p>Someone passed this? And how?</p>
