The danger with editing the stylesheet of the theme is that any time you install an update for the theme it will erase your changes. So the best way to make style changes without that happening is by using a custom CSS plugin. I recommend SiteOrigin’s CSS editor. You can install it by logging into the WordPress admin of your site and going to Plugins > Add New. Then type “siteorigin css” into the search box on the top right and hit enter. It will be one of the first results that you see.
Once you’ve installed it go to Appearance > Customs CSS. This will show you a screen with a text editor containing any custom CSS you have implemented, so it will be blank to begin with. Click the eye icon on the top right of the text editor and this will take you to a visual editor of the site where you can edit the styling of the various site elements by clicking on them in the window on the right and applying alternative styling to them with the inputs on the left. All changes show you a real-time preview so it’s easy to know what you’re changing. Alternatively if you are familiar with CSS you can just bypass the visual editor and make the customizations to the stylesheet by entering them directly into the text editor.
Once you’ve made your desired changes click the tick icon at the top of the left sidebar. This will close the visual editor and display the updated style changes in the text editor. Click the “Save CSS” button below the text editor and your styling changes will now be applied to the site. These style changes are independent of the theme itself and are safe from being overwritten by any future theme updates that may occur.