Hi @askemerci,
Thanks for reaching out.
Instead of implementing the code from that thread, please add this CSS to Theme Options > CSS .
.single-post .entry-featured, .single-post .entry-featured img {
width: 100vw;
position: relative;
}
@media (min-width: 1200px) {
.single-post .entry-featured {
left: calc( 0vw - ( 50vw - ( 1200px / 2 ) ));
}
}
@media (max-width: 1199px) {
.single-post .entry-featured {
left: calc( 0vw - ( 50vw - ( 88% / 2 ) ));
}
}
Then make sure to change the 1200px and 88% with the value you have set in Theme Options > Layout and Design

Example, if it’s changed to 1024px and 90%.
.single-post .entry-featured, .single-post .entry-featured img {
width: 100vw;
position: relative;
}
@media (min-width: 1024px) {
.single-post .entry-featured {
left: calc( 0vw - ( 50vw - ( 1024px / 2 ) ));
}
}
@media (max-width: 1023px) {
.single-post .entry-featured {
left: calc( 0vw - ( 50vw - ( 90% / 2 ) ));
}
}
Thanks!