title: ID instead of Class - CSS Grid
body: <p>I am new here, I have been reading many many many answers without registering, through Google search results, but this time I can't find the answer, although it seems simple...</p>
  
  <p>I have made a page layout using the new, to me, CSS Grid, as a way to learn it, originally  I used classes for the container DIV, and the sub "DIV", for which I have used the HTML5 tags HEADER, NAV, ASIDE and FOOTER, and all seemed to be working fine, even on IE10 with the help of -ms...</p>
  
  <p>The I decided to change the classes to ID, since the main tontainer, which I called "page", would only be used once on each page, as well as the fact that the pages will only have one of header, two navs (which have different IDs, one main-navy and one sub-navy) and all the other elements follow that logic so since they are all main elements of the page, and will only be used once per page, I though that IDs would be better fit...</p>
  
  <p>Now since I converted the classes to IDs, half of the sub DIVs don't work anymore, as in the information is not attached from css, the main container, head and main-NAV work exactly as before, but all the rest don't have any style attached, I have checked with the Chrome Dev Tool, and the style for those sub DIVs is not attached at all...</p>
  
  <p>I have even tried replacing the new HTML5 tags to a standard DIV, assigning the ID as a basic word such as "test", and replaced the related css selector with #test, but the style is not applied at all for the "test" section...</p>
  
  <p>Now as far as the difference between IDs and classes, apart from the fact that one is unique and the other can be repeated, and apart from their relation to other languages, such as the relation to JS I keep reading about, there shouldn't be any differences or am I wrong?</p>