Fix font size for 'Customize' button label.

Bug: 935260
Change-Id: Iad79fdf7da3ddfdb1c746c80f9636ac752d1cbbe
Reviewed-on: https://chromium-review.googlesource.com/c/1490113Reviewed-by: Kristi Park <kristipark@chromium.org>
Commit-Queue: Gayane Petrosyan <gayane@chromium.org>
Cr-Commit-Position: refs/heads/master@{#636242}

chrome/browser/resources/local_ntp/custom_backgrounds.css

@@ -88,6 +88,7 @@ html[darkmode=true] .ep-enhanced #edit-bg-icon {
 .ep-enhanced #edit-bg-text {
   color: rgb(var(--GB600-rgb));
   display: inline;
+  font-size: 14px;
   padding-inline-end: 12px;
   padding-inline-start: 8px;
 }