Font Awesome changing default WordPress Font

It was not Font-Awesome that changed the default WordPress Style. I also use Bootstrap. One file called scaffolding.less overrides the WordPress defaults with:

// Body reset

html {
  font-size: 10px;
  -webkit-tap-highlight-color: rgba(0,0,0,0);
}

body {
  font-family: @font-family-base;
  font-size: @font-size-base;
  line-height: @line-height-base;
  color: @text-color;
  background-color: @body-bg;
}

I just added this to my custom CSS File (original WordPress CSS) with !important:

/* Override Bootstrap Reset with WP default */
body {
    font-family: -apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Oxygen-Sans,Ubuntu,Cantarell,"Helvetica Neue",sans-serif !important;
}

Now WordPress looks like it should again.