✨ Rework buttons classes and variants

Add a conditional class and list props as BEM class modifiers

src/components/molecules/EmailForm.svelte

@@ -2,6 +2,7 @@
     import { getContext } from 'svelte'
     // Components
     import IconArrow from '$components/atoms/IconArrow.svelte'
+    import ButtonCircle from '$components/atoms/ButtonCircle.svelte'
 
     export let past: boolean = false
 
@@ -20,9 +21,13 @@
                 on:focus={toggleFocus}
                 on:blur={toggleFocus}
             >
-            <button type="submit" form="sib-form">
+            <ButtonCircle
+                type="submit" form="sib-form"
+                color="pink" size="small"
+                clone={true}
+            >
                 <IconArrow color="white" />
-            </button>
+            </ButtonCircle>
         </div>
 
         <input type="text" name="email_address_check" value="" style="display: none;">