I verified your code and it is ok. You respected what is asked. Try to refresh your page, verify that the zoom of your page is at 100%. Check if you don’t have extensions such as Adblock or dark mode activated. If it still doesn’t work, maybe try another browser.
yep probably. pops up and dark mode depending on browser and your secuirty also can defintally block it. certain virus protection, can if its way to strict