Fixing this issue is not difficult so you don't have to know about code or any complex information about technology. Shall we get started?

Step 1: Login to your Shopify admin > go to the Online Store 

Step 2: After going to the Online store, the screen will display many themes. You need to click on the Actions button on the theme including the issue

Step 3: You'll be redirected to theme code files. On the search files bar, search the file 'global.scss.liquid' in Asset folder

Step 4: Next, you find a text including ' :has ' in the code source and delete 3 lines (illustrated in the image)

Finally, click on the SAVE button placed at the top right corner to complete fixing. Tada, the issue is gone!