Normally archives will be shown in a unordered list (ul) element:
[archives type="birthmonth" order="ASC" /]
However, this (or any) unordered list can be formatted using css. Here is an example of how to turn the list in to a grid using the CSS columns attribute:
First, we define a UL class that we can later assign:
ul.grid {
list-style: none;
columns: 4;
}
Now we just need to assign this class to our list:
[archives type="birthmonth" order="ASC" class="grid" /]