Hi there,
first off lets fix the button overlapping the Summary on smaller screens.
Replace this block of CSS:
.blog .entry-summary .read-more-button-container, .archive .entry-summary .read-more-button-container {
position: absolute;
bottom: 0px;
}
With:
.entry-summary {
display: flex;
flex-direction: column;
justify-content: space-between;
}
.blog .inside-article .post-image {
max-width: calc(46% - 2em);
}
The 54% width is the width of the post container. I included the max-width of the post image above so it occupies the remaining space.
After that is just down to how you want it displayed on smaller screens.