Overfull hbox too wide

How can I fix this warning?

Here’s the code:

 begin{figure}[hbt!]
includegraphics[width=8cm]{EMNLP2020_demo/Figures/landing_page.png}
caption{The landing page of  href{http://www.openframing.org}{openframing.org}}
label{landing_page}
end{figure}