I have been having a problem with the styles on my custom blog theme that I’m making. When I create a post and then publish it what the post looks like in the back end is different to the front end, The back end is laid out nice and how I want and then in the front end it does not have line spaces/line breaks, Also images will not fully stretch to the full width of the what I have in the back end.

I did add these styles before to allow me to align images and that worked fine, but I am wondering if there is other styles I need to add to make the paragraphs have spaces in-between paragraphs
and able to full width the images.

.alignleft {
display: inline;
float: left;
margin-right: 1.5em;
}

.alignright {
display: inline;
float: right;
margin-left: 1.5em;
}

.aligncenter {
clear: both;
display: block;
margin-left: auto;
margin-right: auto;
}

I was looking at post format does that have something to do with it?

any help i would be grateful thanks