PDF in campaign doesn't open directly in browser

PDF in campaign doesn't open directly in browser

Hi - I've sent a campaign with a button to click to access a newsletter. When the button is clicked, the browser opens and shows whatever the user was last looking at, whilst the newsletter opens in the background. The user then needs to realise that it is a download and click again. I want the user to click the button and for the newsletter to appear immediately on their screen with no other clicks needed. How do I do that?