I have a new question. But I think it's not very difficult.
My test web page has an article whose pathway (breadcrumbs) is Inicio-> Actividades-> Temporada 2017-2018 -> Actividades con profesorado. It has a big blank space in the middle of the page. I had to put it like that because it's not seen properly on mobile phones. How can I remove it or fix it? The article is made with BS3 grid (rows and div classes). My goal was to do something similar to the home page module (home-4) but a bit modified to put a video inside the article.
Perhaps there is an easier way to get it. I don't like floats next to text. It's too close to text.