Links have two underlines – why?!

Hello,

I have styled my links to have a bold underline, using the following code.

However, my links seem to have two underlines. How do I remove the thin underline that is appearing?

In addition, if you scroll down the page to the social icons, I have somehow underlined the icons too. How do I remove this, please?

Thanks

.single-post .entry-content a {
padding: 1px 0px;
font-weight: bold;
border-bottom: 3px solid;
}

.single-post .entry-content a: hover {
border-bottom: 0px;
}

.page a, .archive a {padding: 1px 0px;
font-weight: bold;
border-bottom: 3px solid;
}

.page a, .archive a {
border-bottom: 0px;
}

The page I need help with: [log in to see the link]