Change both style.css and responsive.css

Hi, I'm adjusting this theme according to my needs in a style.css file in a child theme. Now I just saw that there is also a file called responsive.css in the original theme. So far I've made the following changes in my new style.css: #hgroup.with-logo {clear: none; float: left; text-align: center; margin-left: 10px;} #site-title a:hover, #site-title a:focus, #site-title a:active {color: #000;} #hgroup {text-align: center;} #main {min-height: 500px;} Do I also need to make changes to responsive.css (and maybe even to ie.css), or is it enough if I make the required adjustments in style.css? Thanks a lot for your help!