There are a few ways to accomplish this. One way is to add an automatic left margin to the tree:
margin-left: auto;
Another option would be to apply float: right;
to the tree, which may or may not result in the content flow you need.
And finally, my recommendation honestly would be to just use flexbox.
Margin Example
#foo {
display: block;
width: 500px;
height: 500px;
background: #5e5e5e;
}
#tree {
width: 100px;
height: 30px;
background: #000000;
margin-left: auto;
}
<div id="foo">
<div id="tree">Some Text here</div>
</div>
Float Example
#foo {
display: block;
width: 500px;
height: 500px;
background: #5e5e5e;
}
#tree {
width: 100px;
height: 30px;
background: #000000;
float: right;
}
<div id="foo">
<div id="tree">Some Text here</div>
</div>
Flex Example
#foo {
display: flex;
justify-content: flex-end;
width: 500px;
height: 500px;
background: #5e5e5e;
}
#tree {
display: flex;
width: 100px;
height: 30px;
background: #000000;
}
<div id="foo">
<div id="tree">Some Text here</div>
</div>