.entry-full_content {
    max-height: 0;
    opacity: 0;
    overflow: hidden;
    transition: max-height 1.5s ease-in-out, opacity 1.5s ease-in-out;
}

.entry-full_content.is-open {
    max-height: 2000px;
    /* Adjust if content is expected to be longer */
    opacity: 1;
}

/* Ensure hidden class is not interfering if we switch logic completely, 
   but for safety against previous styles: */
.entry-full_content.hidden {
    display: none;
}

/* Border and Shadow for the container when content is open */
.col.post-item.has-open-content {
    border-right: 1px #AAA solid;
    -webkit-box-shadow: 5px 5px 18px 1px rgba(0, 0, 0, 0.07);
    box-shadow: 5px 5px 18px 1px rgba(0, 0, 0, 0.07);
    transition: border-right 0.3s ease, box-shadow 0.3s ease;
}