Images won't centre/align properly

For some reason photos won’t align properly when posted.

They align fine when i’m adding them to the post section, but when posted it doesn’t matter what alignment I select, nothing changes!

They seem to jus align to the right by default.

Heres my css:

/*
Theme Name: Minimal Theme
Author: Zach Kirlew for AndreaAntoniou.co.uk
Author URI:
Version: 1.0
*/

body {
font-family: Georgia, serif
font-size: 14px;
color: black;
text-align: center;

}

#title{
color: black;
text-decoration: none;
font-size: 56px;
}

a:link,
a:visited {
color: black;
text-decoration: none;
}

p {
line-height: 1.65em;
font-size: 18px;
}

h2{
font-size: 30px;
padding-top: 5px;

}
h4{

padding-bottom: 20px;

}

/* General Layout */
div.container {
max-width: 920px;
margin: 0 auto;
padding-left: 20px;
padding-right: 20px;

}

article.post {
border-bottom: 2px dotted #bbbbbb;

}

article.post.img {

display: block; margin-left: auto; margin-right: auto
}

article.post:last-of-type {
border-bottom: none;
}
img.alignright {float:right; margin:0 0 1em 1em}
img.alignleft {float:left; margin:0 1em 1em 0}
img.aligncenter {display: block; margin-left: auto; margin-right: auto}
.alignright {float:right; }
.alignleft {float:left; }
.aligncenter {display: block; margin-left: auto; margin-right: auto}

/* Header */
.site-header {

}

/* Footer */
.site-footer {
margin-top: 30px;
border-top: 2px solid #999;
}

/* Navigation Menus */
.site-nav ul{
margin: 0;
padding: 0;
}

.site-nav ul: before, .site-nav ul:after {content: “”; display: table;}
.site-nav ul:after{ clear: both; }
.site-nav ul: { *zoom: 1;}

.site-nav ul li {
list-style: none;
float: left;
}
.site-nav ul li a:link,
.site-nav ul li a:visited {
display: block;
}

.site-nav ul ul {
display: none;
position: absolute;
}
.site-nav ul ul li { /* this targets all submenu items */

float: none;

width: 150px; /* set to the width you want your sub menus to be. This needs to match the value we set below */

}

.site-nav ul ul li a { /* target all sub menu item links */

padding: 5px 10px; /* give our sub menu links a nice button feel */
background-color: white;

}

.site-nav ul li:hover > ul {

display: block; /* show sub menus when hovering over a parent */

}

/* Header Nav Menu */
.site-header nav {
margin-top: 30px;
}

.site-header nav ul li {
margin-right: 5px;
}

.site-header nav ul li a:link,
.site-header nav ul li a:visited {
padding: 10px 24px;
text-decoration: none;

}

.site-header nav ul li a:hover {
background-color: #000;
color: #fff;
}

/* Footer */
.site-footer {
margin-top: 30px;
border-top: 1px solid #DDD;
font-size: 84%;
}

/* Footer Nav Menu */
.site-footer nav {
margin: 30px 0 10px 0;
}

.site-footer nav ul li {
margin-right: 10px;
padding-right: 10px;
border-right: 1px solid #DDD;
}

.site-footer nav ul li:last-of-type {
border-right: none;
}

/*Page navigation */
div.alignleft {
text-align: left;
}
div.alignright {
text-align: right;

}

/* Page Layout */
article.page h2 {
font-size: 24px;
margin-bottom: 15px;
}

/* Share Icon Css */
.a2a_svg, .a2a_count {
border-radius: 0 !important;
}
/* Share Header */
.addtoany_header{
font-size:13px;
color: #5E5E69;
font-weight: bold;
}

/*Excerpt Text */
.excerptText{
font-style: italic;
color: #5E5E69;
font-size:13px;

}

/* MEDIA QUERIES*/
@media screen and (max-width:919px){
div.container {
width: 100%;

}
#left-column{
width:70%;

}
#right-column{
width:30%;

}

img{

width: 100%;

}

}