How to add a transparency watermark as background image in HTML and CSS HTML with transparent watermark. CSS/HTML/sass — CSS3 I've tried to add transparent blue watermark and as the background image in HTML and CSS. How to add transparency into an HTML page using CSS background image HTML — Watermark Images I haven't completed the watermark in the background color. How to add transparent in HTML and CSS HTML — I don't believe that it's possible to add transparent image to web page? HTML : I was able to add transparent image.