I have tested Simple Job Board plugin with all your themes and none of them is displaying this plugin correctly. Jobs archive is overlapping with the Header, etc. To whom should I address this issue, to you, or to the creator of the plugin?
We have not test our theme with Simple Job Board Plugin. The plugin should have provided with the option to manage the HTML structure so that you can manage the HTML to work with any theme. So please contact the Plugin developer. If you want us to look, it would fall under paid support.