add size tokens

app/javascript/styles/mastodon/theme/_base.scss

@@ -25,3 +25,24 @@
   --color-green-400: #05df72;
   --color-green-600: #00a63e;
 }
+
+@mixin spacing {
+  --spacing-none: 0;
+  --spacing-xxxs: 2px;
+  --spacing-xxs: 4px;
+  --spacing-xs: 8px;
+  --spacing-sm: 12px;
+  --spacing-md: 16px;
+  --spacing-lg: 24px;
+  --spacing-xl: 40px;
+}
+
+@mixin radius {
+  --radius-none: 0;
+  --radius-xxs: 4px;
+  --radius-xs: 8px;
+  --radius-sm: 12px;
+  --radius-md: 16px;
+  --radius-lg: 24px;
+  --radius-full: 50%;
+}

app/javascript/styles/mastodon/theme/index.scss

@@ -5,6 +5,8 @@
 
 html {
   @include base.palette;
+  @include base.spacing;
+  @include base.radius;
 }
 
 [data-color-scheme='dark'],