Child theme modifies site without changes

I’m trying to create a child theme for Kuorinka but without even adding anything but comments in the child style.css the layout changes completely. Screenshot of how the layout breaks: Child theme problem. What is going wrong?

I followed the instructions on example child theme for Kuorinka. My style.css now simply looks like this:

/**
 * Theme Name:  Kuorinka Child Dev
 * Theme URI:   https://foxland.fi/downloads/kuorinka
 * Description: Dev child theme for Kuorinka theme
 * Version:     1.0.0
 * Author:      Sami Keijonen
 * Author URI:  https://foxland.fi
 * Text Domain: kuorinka-child-dev
 * Domain Path: /languages/
 * Tags:        blue, white, light, one-column, two-columns, left-sidebar, right-sidebar, fluid-layout, responsive-layout, accessibility-ready, custom-background, custom-header, custom-menu, editor-style, featured-images, flexible-header, full-width-template, microformats, post-formats, rtl-language-support, sticky-post, threaded-comments, translation-ready
 * License:     GNU General Public License v2.0 or later
 * License URI: https://www.gnu.org/licenses/gpl-2.0.html
 * Template:    kuorinka
 */