Data Grid - Horizontal Scrolling

I have a data grid with 20+ columns, and the desired user experience is to have horizontal scrolling. I've attempted to implement this with the method found at the following link, but it doesn't seem to work with 5.12. Any suggestions?
2 answers

The element you want to resize is now called the .mx-datagrid-content-wrapper, and tundra isn't necessary either.

You should be able to use the css class below:

 .wideGrid2000 .mx-datagrid-content-wrapper {
     width: 2000px;

What Jasper explained is true, but to achieve an independent horizontal scroll-bar you need to:

  1. Explicitly define your width in your table cell or container (the classing will override this otherwise)
  2. Define set these two classes (using the custom class "horizontalgrid"). :

.horizontalgrid .mx-datagrid-head-table { background-color: #ffffff; margin-bottom: 0; position: relative; width: 1500px !important;
} { border-top: medium none; margin-bottom: 0; table-layout: auto; width: 1500px !important; }

P.S. I've added "!important" because I'm lazy, you can choose to set the update the class a level up too