???
Hmm I don’t get that one… Looks like a browser rendering error to me. Some of the lines around cells, like the one which is missing in your pic, are a little too wide on my PC, because of zooming levels… Try CTRL+0 or whatever sets your zoom level to normal? Have you rebooted? Perhaps you added a new plugin to your browser recently?
because of zooming levels
geeee yes i have used zooming lately