Migrate Makefile entries to shell.nix

Isolate the whole nodejs/yarn stuff.
Migrate from node-sass to dart sass in order to do so.
Easier to install, less dependencies (no python, no compiling while yarn
install)

Resources/Private/Sass/Frontend/components/_adminpanel.scss

@@ -4,8 +4,8 @@
     border-color: $yellow-dark;
     color: $black-dark;
     padding: {
-        top: $spacer / 4;
-        bottom: $spacer / 4;
+        top: calc($spacer / 4);
+        bottom: calc($spacer / 4);
         left: $spacer;
         right: $spacer;
     }

Resources/Private/Sass/Frontend/components/_admonition.scss

@@ -1,9 +1,9 @@
 aside {
     &[class^='admonition-'] {
         border: none;
-        border-left: solid $spacer / 4;
-        padding: $spacer * 2;
-        margin-top: $spacer * 2;
+        border-left: solid calc($spacer / 4);
+        padding: calc($spacer * 2);
+        margin-top: calc($spacer * 2);
 
         h1, h2, h3, h4, h5, h6 {
             padding-top: 0;

Resources/Private/Sass/Frontend/layout/_elements.scss

@@ -42,9 +42,9 @@ strong {
 
 blockquote {
     border: none;
-    border-left: dashed $spacer / 4;
+    border-left: dashed calc($spacer / 4);
     padding: $spacer;
-    margin-top: $spacer * 2;
+    margin-top: calc($spacer * 2);
     border-color: $white;
 
     &:before {
@@ -69,7 +69,7 @@ ol {
 
 li {
     padding: {
-        bottom: $spacer / 2;
-        top: $spacer / 2;
+        bottom: calc($spacer / 2);
+        top: calc($spacer / 2);
     }
 }

gulpfile.js

@@ -1,5 +1,5 @@
 const { src, dest, parallel, watch } = require('gulp');
-const sass = require('gulp-sass');
+const sass = require('gulp-dart-sass');
 const minifyCSS = require('gulp-csso');
 
 const frontendSassFolder = 'Resources/Private/Sass/Frontend/';

package.json

@@ -5,17 +5,15 @@
         "watch": "gulp watch"
     },
     "engines": {
-        "npm": "6.12.*",
-        "node": "12.*"
+        "node": "16.*"
     },
     "dependencies": {
         "bootstrap": "^4.3.1",
         "gulp": "^4.0.2",
         "gulp-cli": "^2.2.0",
         "gulp-csso": "^3.0.1",
-        "gulp-sass": "^4.0.2",
+        "gulp-dart-sass": "^1.0.2",
         "jquery": "^3.4.1",
-        "popper.js": "^1.16.0",
-        "sass": "^1.23.3"
+        "popper.js": "^1.16.0"
     }
 }