Osclass Project

I have a website running CMS Osclass and zara theme. I need some little customization for it, especially in mobile view. Please check attachment. The first task is make minor change in the Search Form/function. Instead of using slider, I want to replace the price field into Text Input where user can type minimum and maximum price The second one is much easier. When I click on the flag, there should be a drop down option but somehow some parts of it is not visible. I need you to fix it.