[x/go.dev] learn: fix event image sizing
[x/go.dev] learn: fix event image sizing

Change-Id: Ic56248c56f926542aeb4532a6243433584d55310

X-GoDev-Commit: efa568df1c145f895bafaf986be030fdd3f2a69c

golang/website,golang/website,golang/website,golang/website,golang/website,golang/website,golang/website