We offer two of the most popular choices: normalize.css and a reset.div class"scrollbar" id"style-1"> <. Therefore, it is appropriate to use an ID on the div element that is marking up the main content on the page, as there will only be one main content section.Saying that you have only one header and such so you need id instead of class might be correct. But lets say you have a search bar with style Second div (mysticky-wrap) is used to add a .wrapfixed class on scroll event and by default it has 100 width.So now we can define some custom css style using .myfixed css class field to achieve desired styleI was created nav menu and put id, but when i scroll down all elements put to the left HTML elements can have more than one class name, each class name must be separated by a space. Example. Style elements with the class name "city", also style elements with the class name "main" Otherwise, when you have a unique style that you want to give to just ONE element, use id.