Thesis stylesheet is missing

Can you tell me if this is something I should be worried about? I haven’t been keeping track of all the little changes to colors, etc, but do I need to create a child theme? If so, can I simply make a copy of my entire theme folder in its current state and rename it parenttheme-child, then activate the “child theme” and make changes to the child theme folder’s css files from here on out? All I really want to do is ensure that any changes I’ve made and will continue to make end up staying there, even after doing necessary updates in the future!

Thesis stylesheet is missing

thesis stylesheet is missing

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thesis stylesheet is missingthesis stylesheet is missingthesis stylesheet is missingthesis stylesheet is missing