Using BEM, responsive mobile first some javascript and a Back Button !

Hello everyone, I would like to receive comments about the code. What do you think of the css code with BEM? What other option could I have used to avoid having to separate the pages in two? It's a simple challenge, but it served me well for another project. Separate the modules in two different pages, so that the html code is better to read, otherwise I would have used javascript to load them dynamically. Thanks in advance!!