Anchors are inline and the <p> tag is a block element. That won’t let them be on the same line the way you have it set up.
You could set both to display:inline-block though. This lets them both basically be display:inline (thus let them both be on the same line) while allowing for some display:block functionality. Best of both worlds.
It takes up all space available. It would expand out to 6000px if your container/viewport was that big.
Block elements take up all space available (by default.)
Inline elements are shrink-to-fit
Inline-block elements are shrink to fit
Table-cells are shrink to fit