Using WordPress Child Theme to Use Custom CSS in WordPress Site

style.css

/*
 Theme Name:   Twenty Fifteen Child
 Theme URI:    http://freewptp.com/
 Description:  Twenty Fifteen Child Theme
 Author:       Movin
 Author URI:   http://freewptp.com/
 Template:     twentyfifteen
 Version:      1.0.0
 License:      GNU General Public License v2 or later
 License URI:  http://www.gnu.org/licenses/gpl-2.0.html
 Tags:         light, dark, two-columns, right-sidebar, responsive-layout, accessibility-ready
 Text Domain:  twenty-fifteen-child
*/

.entry-header .entry-title a{
	font-size: 30px;
}