While looking at the code of some sites including Netflix and W3Schools, I noticed something odd: when looking at some elements (by clicking Inspect Element in Firefox Developer Edition), almost all of the CSS rules/strings were crossed out. Why would that be? I attached two screenshots, 1 shows many crossed lines and 2 shows what element I was expecting.1 2
The majority of those rules crossed out are fallbacks for specific browsers.
-webkit is Chrome and Safari,
-moz is Firefox,
-o is Opera and
-ms for Internet Explorer.
