sass: add white-space: normal to buttons

File names are so long that, on mobile, it goes beyond the screen.
Wrapping it doesn't look all that awful, so let's do it.

Side note: LOS download page does this too.

_sass/base.scss

@@ -112,6 +112,7 @@ img {
 }
 
 .btn, .btn a, a.btn {
+	white-space: normal;
 	text-decoration: none;
 }