Possible small improvements:
In the continuation of Farhan's suggestion about buttons color, this is the same for the selection checkmark, the vivid blue of an unselected checkmark suggests a selected post until we see another unselected post with the same color, if it exists.
BTW, I don't like the vivid blue.
It looks aggressive, a more matte shade would be better for me. Eyes are attracted by the colon of blue arrows in a page with short posts:
Maybe something like that would be possible, given the other constraints:
Or maybe the good magenta omnipresent in aviation displays: