First, let's look at the OS style field option and what we get with it. When designing a field, you can choose to make it look more "Windows-like" (or "Mac-like" or whatever the flavor of your operating system) by selecting the "Native OS style" option. When you do this, you can control the formatting of the field slightly by manipulating the border style and setting the background color. However, Notes does not give you an option to manipulate the size of the border or its color.
Here's the trick for designing the border however you'd like. Instead of using the border style properties of the field, enclose the field within a table cell and set the border style of the field to 'None'. The border for the table then effectively becomes the field's border. Since it is just a standard Notes table, you can style it up however you'd like, changing the border weight, color, etc. Here's a few examples:
The design of the first one is borrowed from Trans-Siberian Orchestra's fan club sign up page. I changed the fields to be light colored orange with a dark orange border (by the way...here's another great use for layers...putting fields on top of a background).
The second example is from an actual document library database, which shows a more subtle use of this effect. The borders of the field are light grey instead of black, which makes them blend better with the overall color scheme of the page.
The final example is pretty out there, but it shows what you can do if you experiment a bit. In this case, I gave the tables that enclose the fields a border style of "Image", selected an image from the database and increased the thickness to seven pixels. Quite an interesting effect.
Keep in mind that all of these screenshots are from the Notes client. Don't believe me? :-) Here's a shot in design mode (showing all of the relevant settings of course).
A couple of other things to keep in mind:
-If you want to control the width of the field, use the OS style and set it to a fixed width. Make sure to turn off the "Allow multiple lines" display option on the second tab. This will prevent the user from using a carriage return in the field.
-If you want your field to be able to grow as the user types in text, use the standard Notes style field and then uncheck the option to "Show field delimiters". If you choose to use this type of fluid design construct, make sure it will not mess up the formatting of your form as the table grows.
Overall, this is an elegant and easy to implement solution. Just how I like it.
Happy Holidays everyone!