Some websites use WebGL for hardware-accelerated interactive 2D and 3D graphics. When you visit one, Safari may ask whether you want to trust the website’s use of WebGL. You have these choices:
Trust: Safari lets the website use WebGL, and doesn’t ask about it if you visit the site again.
Not Now: Safari doesn’t show WebGL content for this site now or when you visit the site again in the next 24 hours. If you visit the site after that, Safari asks again whether you want to trust the site’s use of WebGL.
Never for this Website: Safari doesn’t ever show WebGL content for this site.
Change the blocking policy for future visits: Choose Safari > Preferences, click Security, then click WebGL Settings next to Allow WebGL. For information about the policy options, see Security pane of Safari preferences.