Post/page centering image

I can’t get the image in the post to align center (or right for that matter). I tried everything…

I put this in custom css (just in case)

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}
a img.alignright {float:right; margin:0 0 1em 1em}
a img.alignleft {float:left; margin:0 1em 1em 0}
a img.aligncenter {display: block; margin-left: auto; margin-right: auto}

And then referenced it in the class of image. I tried it using wordpress wsiwyg. no dice. Please help. I’m working with image on main page if you scroll down a bit. https://Vantagerecoverysupport.com