Vertical Alignment Of Checkboxes Using CSS

Working on converting some of the forms on our website to be housed within our new emailing platform (Pardot, a part of Salesforce). Using their CSS editor to create the forms, but I don't have much experience in CSS. I got all the labels for a checkbox to align vertically, but they're in a diagonal line instead of a vertical line. Any tips on how to fix that?

I also attached an image of what the form looks like on the website. Image is here.

Here's the CSS:

pardot-form input[type="checkbox"] {
  background-color: #fff;
  color: #666;
  font-family: "Open Sans", sans-serif;
  font-size: 14px;
  line-height: 1.75em;
  height:18px;
  width:18px;
  padding:0;
  margin-top:5px;
  display:block;
  float:left;
}