Use this handy, simplified guide to quickly learn HTML and CSS -- a foundation of modern web development.

By appending just a few lines of HTML and CSS code, researcher Louis Dion-Marcil showed how an external sender could hide the very warning from an email message.

Now [Andy Green] has extended the possibilities with affordable silicon, by producing a proof-of-concept HTML + CSS renderer over h2 on ESP32 for libwebsockets.

Inside the CSS code they add a CSS variable which stores the URL location of the web skimmer code they want to load inside a hacked store.