Answered: line dashed problem

Edit:

One of your plugins is adding those inline styles, you'll just have to figure out which one.

Follow these steps but instead of removing plugins, disable them one by one to see which one is causing that, once you figure it out, you can go from there.

Looks like you've already customized it to be:

hr {
     border-top: 2px dashed #000;
}

Now you just have to tweak it.

The original one already is somewhat of a border 1px solid.
Here´s an example: