Move CSS to remove button styling into mixins.scss

stylesheets/_conversation.scss

@@ -751,13 +751,7 @@ span.status {
   cursor: pointer;
 
   button {
-    background: none;
-    color: inherit;
-    border: none;
-    padding: 0;
-    font: inherit;
-    cursor: pointer;
-    outline: inherit;
+    @include remove-button-styles;
   }
 
   .first-line {
@@ -875,13 +869,7 @@ span.status {
   margin-right: auto;
 
   button {
-    background: none;
-    color: inherit;
-    border: none;
-    padding: 0;
-    font: inherit;
-    cursor: pointer;
-    outline: inherit;
+    @include remove-button-styles;
   }
 
   .image-container {

stylesheets/_mixins.scss

@@ -1,3 +1,13 @@
+@mixin remove-button-styles() {
+  background: none;
+  color: inherit;
+  border: none;
+  padding: 0;
+  font: inherit;
+  cursor: pointer;
+  outline: inherit;
+}
+
 @mixin color-svg($svg, $color) {
   -webkit-mask: url($svg) no-repeat center;
   -webkit-mask-size: 100%;