Shawburn: use font-base for buttons

shawburn/style-editor.css

@@ -300,7 +300,7 @@ object {
 	color: white;
 	font-weight: 700;
 	font-family: "PT Sans", Arial, sans-serif;
-	font-family: var(--font-headings, "PT Sans", Arial, sans-serif);
+	font-family: var(--font-base, "PT Sans", Arial, sans-serif);
 	font-size: 0.83333em;
 	line-height: 1;
 	background-color: #0C80A1;

shawburn/style-rtl.css

@@ -1082,7 +1082,7 @@ input[type="submit"],
 	cursor: pointer;
 	font-weight: 700;
 	font-family: "PT Sans", Arial, sans-serif;
-	font-family: var(--font-headings, "PT Sans", Arial, sans-serif);
+	font-family: var(--font-base, "PT Sans", Arial, sans-serif);
 	font-size: 0.83333rem;
 	background-color: #0C80A1;
 	border-radius: 4px;

shawburn/style.css

@@ -1082,7 +1082,7 @@ input[type="submit"],
 	cursor: pointer;
 	font-weight: 700;
 	font-family: "PT Sans", Arial, sans-serif;
-	font-family: var(--font-headings, "PT Sans", Arial, sans-serif);
+	font-family: var(--font-base, "PT Sans", Arial, sans-serif);
 	font-size: 0.83333rem;
 	background-color: #0C80A1;
 	border-radius: 4px;