Copied the definition of '.abs-account-title' from Luma to Blank so they can both use it.

Author: hostep

app/design/frontend/Magento/blank/web/css/source/_extends.less

@@ -849,6 +849,24 @@
     }
 }
 
+//
+//  Account pages: title
+//  ---------------------------------------------
+
+& when (@media-common = true) {
+    .abs-account-title {
+        > strong,
+        > span {
+            .lib-font-size(22);
+            .lib-css(font-weight, @font-weight__light);
+        }
+
+        .lib-css(border-bottom, 1px solid @border-color__base);
+        .lib-css(margin-bottom, @indent__m);
+        .lib-css(padding-bottom, @indent__s);
+    }
+}
+
 //
 //  Ratings: vertical alignment
 //  ---------------------------------------------