I decided I wanted to underline my Gadgets yesterday. So I looked around for ways to do it.
This will be in your CSS. Go to Customize>Advanced>Add CSS.
Copy and paste the following into the CSS box;
font-family: 'georgia' !important;
text-transform: uppercase !important;
border-bottom: 2px dashed grey;
It didn't work for me. Normally you can see it change right then. So I hit the space button and there it was. Not sure why this sometimes works.
Okay, say you want to change some of these lines of code. I'd leave the first line alone. It's up to you what font size you want. The font weight I'd leave alone. The font family you could change; I chose not to. I'd leave text-transform alone. Border bottom you can change pixels, though you don't want much over 2 px. You could change dashed gray, I suppose. But normally it is a hex color like this #000000. And there was no hex code, so I left this alone. Padding bottom I'd leave alone also.
In fact I left the whole code alone and copied and pasted it just as it appears.
UPDATE: I just now tried to add a hex code instead of dashed grey, and it didn't work.
I just went back and changed grey to red on this blog and it worked. I tried dashed black and it worked. So you could try colors with the dash and see what happens.
I went to Cozy Little House and added solid gold instead of dashed grey and it worked also. I went to Color My Decor and typed solid orange and it worked as well.