Apply CSS rules to a nested class inside a div

Question

I don’t know exactly how to apply CSS to a nested element. Here is my example code, but I’m looking for a manual that explains all the rules:

Answer 1

Use Css Selector for this, or learn more about Css Selector just go here https://www.w3schools.com/cssref/css_selectors.asp

#main_text > .title {
  /* Style goes here */
}

#main_text .title {
  /* Style goes here */
}