Bulma v9 website (#3249)

* Add Bulma v9

* Add vendor dependencies

* Fix native

* Fix sponsors

* Add style attribute

docs/_sass/pages/extensions.scss

@@ -0,0 +1,27 @@
+.bd-extension {
+  border-bottom: 2px solid $scheme-main-bis;
+  display: block;
+  padding: 1.5rem;
+
+  .subtitle {
+    color: $text-light;
+  }
+
+  &:hover {
+    background-color: $scheme-main-bis;
+
+    .title {
+      color: $link;
+    }
+
+    .subtitle {
+      color: $text-strong;
+    }
+  }
+}
+
+@include tablet {
+  .bd-extension {
+    padding: 3rem 0;
+  }
+}