BuddyPress.org

Looking more closely at your styles, the problem might be the width of your #item-meta. Remove the margin-top declaration you entered before, and try this instead:

#buddypress div#item-header div#item-meta {
    width: 200px;
}

Your next step is to start getting familiar with CSS 😀 https://developer.mozilla.org/en-US/docs/Learn/CSS/Introduction_to_CSS