Right Margin problem in ADE

So, I'm making a test EPUB using Sigil and I just put some text to experiment with the results...

I just put some text (divided by <span> tags, becuase I'm trying to use Media Overlays) and I don't understand why in ADE, for some reason, I have a wierd right margin that doesn't show in Sigil...

Why does this happen? I'm assuming it's a problem with my CSS code but I just don't know where... My CSS code is this:

@11220649-face {
   font-family:Bitter;
   font-style:normal;
   font-weight:normal;
   src:url("../Fonts/Bitter-Regular.ttf");
}

p {
   text-indent:2em;
   text-align:justify;
   margin:0 0 0 0;
   padding:0 0 0 0;
   border-width:100%;
}

span {
   font-family:Bitter;
   font-style:normal;
   text-indent:2em;
   text-align:justify;
   margin:0 0 0 0;
   padding:0 0 0 0;
   border-width:100%;
}

.-epub-media-overlay-active {
   background-color: #FFFF99;
}

Can someone help me with my problem?