A bunch of currently working options for centering images here:
I think you could use similar for right and left float. e.g.
img[alt*="right"],
.markdown-source-view .cm-content .image-embed[alt*="right"] {
float: right;
padding: 2px 2px 2px 4px;
}
but I noticed it caused some issues editing text / with cursor input in a small section below the image (in live preview).