Zmień kolor znacznika znaku w HTML

 /*Apply to all mark tags*/
mark {
  background-color: blue; /*Add your desired color*/
}
/*Apply it to a class*/
.mark { 
  background-color: blue; /*Add your desired color*/
}
/*Apply it to an ID*/
#mark {
  background-color: blue; /*Add your desired color*/
}
Coder.html