If you did not edit php files from the child theme, the problem caused by custom css code. You can inspect the code on site using inspector tools. To access it, open a web page or web app in Google Chrome. Either:
-Select the Chrome menu Chrome Menu at the top-right of your browser window, then select Tools > Developer Tools.
-Right-click on any page element and select Inspect Element.
The DevTools window will open at the bottom of your Chrome browser.