Q:

Keep element always centered with side text to the left

I need help to structure a page, i thought it was easy but it wasn't, at least not for me.

Logo: always centered, of course.
Element: For instance, an image, always centered. Image can be vertical or horizontal, but needs to be centered.
Text: Next to the element/image. 
There are no boxes really, i saw other questions where they where trying to keep center box always centered, but in this case i just have one main box/container and then text/caption next to the image.
What i cannot do is keeping image centered, because if i add text next to the image, will try to center the whole thing.
Thanks!

A:

Horizontal and vertical centering is most easily solved with flexbox. Simply set the following on your container:
display: flex;
align-items: center;
justify-content: center;
flex-wrap: wrap;

Note that you'll want a height too! I've gone with 100vh to occupy the full viewport.
To centralise your element at the top just give it align-self: flex-start.
From here it's just a matter of having a child which contains both the central item and offset item, both of which need position: absolute. The offset item will additionally want margin-left equal to the width of the centralised item, but it should only be applied inside of a media query.
To drop the offset item below for mobile screens, you'll want a second media query which adds margin-top.
This can be seen in the following (click  Full page after Run code snippet to see the desktop view).

body {
  margin: 0;
}

.container {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  height: 100vh;
}

.top {
  border: 1px solid black;
  width: 50%;
  height: 10%;
  align-self: flex-start;
}

.inner-container {
  border: 1px solid black;
  width: 50%;
  height: 50%
}

.center, .off-center {
  position: absolute;
}

@media screen and (min-width: 769px) {
  .off-center {
    margin-left: 50%;
  }
}

@media screen and (max-width: 768px) {
  .off-center {
    margin-top: 50vh;
  }
}
<div class="container">
  <div class="top">Logo</div>
  <div class="inner-container">
    <div class="center">Center</div>
    <div class="off-center">Off-center</div>
  </div>
</div>

