Hi @imcsoler,
There are a few threads in the forum about OJS 2.x responsive themes (some of them using Bootstrap) – see e.g. Relaciones Internacionales - OJS 2.4.2 + Bootstrap + Google Fonts and more and forum.pkp.sfu.ca/t/is-there-any-free-resource-of-responsive-templates/5782 for a start.
Regards,
Alec Smecher
Public Knowledge Project Team