Reformat rgba() colors (#1781)

* Reformat rgba() colors

* Create nasty-bananas-drive.md

Author: simurai

.changeset/nasty-bananas-drive.md

@@ -0,0 +1,5 @@
+---
+"@primer/css": patch
+---
+
+Reformat `rgba()` colors for `.btn-mktg`

src/marketing/buttons/button.scss

@@ -13,7 +13,7 @@
   white-space: nowrap;
   vertical-align: middle;
   user-select: none;
-  background: linear-gradient(180deg, rgba(255 255 255 / 0.15) 0%, rgba(255 255 255 / 0) 100%), var(--color-mktg-btn-bg) !important;
+  background: linear-gradient(180deg, rgba(255, 255, 255, 0.15) 0%, rgba(255, 255, 255, 0) 100%), var(--color-mktg-btn-bg) !important;
   border: 0;
   // stylelint-disable-next-line primer/borders
   border-radius: 0.375rem;
@@ -29,7 +29,7 @@
     z-index: -1;
     content: '';
     // stylelint-disable-next-line primer/colors
-    background: linear-gradient(180deg, rgba(255 255 255 / 0.15) 0%, rgba(255 255 255 / 0) 100%) !important;
+    background: linear-gradient(180deg, rgba(255, 255, 255, 0.15) 0%, rgba(255, 255, 255, 0) 100%) !important;
     border-radius: inherit;
     opacity: 0;
     opacity: 0;