scope button styles to "outline" variation

parts/footer.html

@@ -16,14 +16,14 @@
     <!-- /wp:outermost/icon-block -->
 
     <!-- wp:buttons -->
-    <div class="wp-block-buttons"><!-- wp:button {"backgroundColor":"light-green"} -->
-      <div class="wp-block-button"><a
+    <div class="wp-block-buttons"><!-- wp:button {"backgroundColor":"light-green","className":"is-style-outline"} -->
+      <div class="wp-block-button is-style-outline"><a
           class="wp-block-button__link has-light-green-background-color has-background wp-element-button">🖂
           info@lexscotland.org</a></div>
       <!-- /wp:button -->
 
-      <!-- wp:button {"backgroundColor":"light-purple"} -->
-      <div class="wp-block-button"><a
+      <!-- wp:button {"backgroundColor":"light-purple","className":"is-style-outline"} -->
+      <div class="wp-block-button is-style-outline"><a
           class="wp-block-button__link has-light-purple-background-color has-background wp-element-button">We're on
           LinkedIn 🡭</a></div>
       <!-- /wp:button -->

theme.json

@@ -295,29 +295,33 @@
         }
       },
       "core/button": {
-        "color": {
-          "background": "#E8BFE2",
-          "text": "var(--wp--preset--color--contrast)"
-        },
-        "spacing": {
-          "padding": {
-            "top": "1em",
-            "bottom": "1em",
-            "right": "2.5em",
-            "left": "2.5em"
+        "variations": {
+          "outline": {
+            "color": {
+              "background": "#E8BFE2",
+              "text": "var(--wp--preset--color--contrast)"
+            },
+            "spacing": {
+              "padding": {
+                "top": "1em",
+                "bottom": "1em",
+                "right": "2.5em",
+                "left": "2.5em"
+              }
+            },
+            "border": {
+              "color": "#000",
+              "width": "1px",
+              "radius": "56px",
+              "style": "solid"
+            },
+            "typography": {
+              "fontSize": "var(--wp--preset--font-size--small)",
+              "fontFamily": "var(--wp--preset--font-family--atkinson-hyperlegible)",
+              "fontWeight": "700",
+              "letterSpacing": "0.64px"
+            }
           }
-        },
-        "border": {
-          "color": "#000",
-          "width": "1px",
-          "radius": "56px",
-          "style": "solid"
-        },
-        "typography": {
-          "fontSize": "var(--wp--preset--font-size--small)",
-          "fontFamily": "var(--wp--preset--font-family--atkinson-hyperlegible)",
-          "fontWeight": "700",
-          "letterSpacing": "0.64px"
         }
       },
       "core/separator": {