Board Thread:Support Requests - Getting Technical/@comment-26293360-20190312221515/@comment-9605025-20190402013214

Part of the reason is because you used "border", which is a shorthand property. Shorthand properties allow a short convenient way for designers to quickly specify multiple properties in a single line. If you omit the value for one of them, it will look to see if the specific property has been specified else where. If so, it will use that value; if not, it will use the standard default.

In this case you want to set "border-style"; which is actually yet another shorthand property. You can do this either by setting it on its own or by adding the value it requires to you existing "border". For example, either of the two rules will do what you want (choose one).