I wanted to "draw" a line around my sidebar gadget titles. In other words, I wanted a solid line that created the look of a box, with the inside remaining white.
Here is what I did: Go to Headings in your blog HTML.
If you have trouble finding it, put your cursor up in the far right-hand corner where there is empty space. Click CTRL and F.
A box will open up. Type Headings in there and you will find everything in your HTML that has that word in it.
Somewhere under Headings, type this...
1px solid #dddddd;
For some reason some of these tips don't work until you hit the space bar. Click Preview and see if it's as you want it. If it is, click Save.
I wanted a light grayish color. Which is the #dddddd. You can Google color hex codes to find other colors to use. Dark black is #000000. White is #FFFFFF.